The Real Truth About Understeer - by Ben in Subaru forums
01-26-2011
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The Real Truth About Understeer - by Ben in Subaru forums
I just came across this in another *cough* forum, and is one of the best compilations i ever seem about understeer -they are talking about understeer in 4WD and track, but it's a good reading, nonetheless.
I thought this was worth sharing. long but worthwhile read.
Josh, i guess you remember this, since you replied in the other post
The original posts can be found in this thread here. Great reading.
http://www.iwsti.com/forums/driving-...ndersteer.html
The Real Truth About Understeer
________________________________________
There was a post made recently that supposedly exposed the "truth" about Subaru understeer. In summary, someone on this forum watched a video of a driver saying that driving too smoothly causes understeer, and that the proper way to corner in a Subaru is to violently whip the steering wheel 70 degrees or so on turn in to eliminate understeer.
Now, hopefully, I don't need to tell you that this is a load of crap. However, the fact that someone watched this video and had some sort of epiphany and wanted to share it with others on this forum was REALLY SCARY. I ended up accidentally writing a fairly long post about how to properly enter a corner in a Subaru, and then went off on a somewhat of a tangent about understeer in general. Because of this, I felt it would be a good idea to take what I already wrote and expand a little bit. It should help 98% of the drivers out there, as understeer is probably the most commonly misunderstood driving concept there is.
If you go to the track, you should read this. Even if you think you know everything there is to know about understeer, you'll probably learn something.
The Real Truth About Understeer
What exactly is understeer? In purely technical terms, it's a lack of front tire grip. But what does that actually mean? What causes it? How can you get rid of it mid-corner? How can you avoid it altogether? And most importantly, why is it actually MORE dangerous than oversteer?
First, let's understand exactly what understeer means. When you enter a corner and the car begins to "push" toward the outside of the turn, you're experiencing understeer. You've dialed in the correct amount of steering input (turned the wheel the correct amount) but the car is turning less than it should.
REASONS FOR UNDERSTEER
So, why does this happen? This happens because your rear tires have more grip than your front tires. When you begin to turn, instead of the front tires gripping on the road, they slide. This can happen for one of three basic reasons:
1) You've entered a corner too fast (surprisingly, this isn't usually the problem!)
2) You're trying to turn too much (you've actually asked the tires to do more than you need them to do)
3) Your brake and/or throttle inputs haven't loaded the front suspension properly (this is your problem, 95% of the time)
Let's discuss #3 first, as this is the most common cause of understeer. To understand load transfer, also commonly (and incorrectly) referred to as weight transfer, perform this simple exercise:
Place your hand face-down on the table/desk in front of you. Slide it forward on the table. Your hand slides easily because you have very little load forcing it on the table. Now stand up, and lean on your hand. While leaning on your hand, try to slide it forward. It doesn't slide. This is because you have a lot of load on your hand. The same exact thing is constantly happening with your tires. When you have load on your tires, they grip. When you don't, they slide.
Simply put, when you accelerate, load is transfered rearward. When you decelerate, load is transfered forward. Deceleration doesn't necessarily mean braking, as coasting or even easing off the throttle will cause the vehicle to slow down (decelerate). This is even more dramatic when driving up hill, as the slightest decrease in throttle input causes the car to decelerate significantly.
BRAKE RELEASE
So, we know that understeer is caused by a lack of front grip, and we know that we can increase front grip by transferring load to the front of the car. So as long as we decelerate before every corner, we'll never understeer ever again! Right? Well, it's not quite that easy.
The way in which we brake and accelerate, or more importantly, the way in which we release the brakes and roll on the throttle, determines how the load is transfered, how much load is transfered, and most importantly, how much load actually STAYS in the front of the car.
If we brake very hard, a lot of load is sent to the front. However, if we abruptly lift off the brakes and get back on to the throttle, all of that load goes right back to the rear. In fact, when you're accelerating hard, the front tires have so little load that they're barely making contact with the ground. Just think about how well your car would steer if you were doing a wheelie through the turn.
So, how can we accelerate through a corner and still maintain a healthy amount of front load and grip? The answer is proper brake release, followed by sensitive throttle input. Ideally, a passenger should not be able to tell when you've gotten off the brakes and on to the gas.
To do this, you need to revise your braking strategy. Braking "late" or "diving" in to corners and getting on the power early may seem like the fastest way around the track, but this usually slows people down. There is a way to brake late and get on to the throttle sooner, but it can't happen until you've mastered proper brake release.
To start out, brake 10-20% earlier than you normally would. Try to get all of your braking done well before the corner. At this point, you should feel like you broke too early. You have a quarter to half a second of time, which feels like an eternity, in which you don't need to be slowing down anymore, but you don't need to be turning yet. During this "dead space" you focus on one thing, and one thing only: brake release. This is your time to gradually release the brakes and begin to turn in. As you get comfortable with this, you can begin braking where you normally did before, combining this smooth brake release with your turn-in, often referred to as "trail braking." You then need to follow this up with an equally smooth and gradual application of throttle. Smashing on the gas at this point will ruin all of the work you've done up this point with your brake release.
If done correctly, one of two things will happen depending on a variety of factors:
1) The car will be perfectly neutral through the turn and will turn exactly the same amount as you turn the steering wheel.
2) The car will oversteer slightly, turning more than you turn the steering wheel.
No explanation is needed for #1. You're good to go. Congratulations, for the first time ever, your Subaru isn't fighting you through a turn.
OVERSTEER AND "ZERO-STEER"
Next, we have situation #2. This is a GOOD situation to be in, do not be afraid! Clearly, hell has frozen over, as your Subaru is oversteering. How could this have happened? The answer is you've successfully trail braked to the point that you actually have so much front grip that your car is able to turn more than you asked of it. Depending on how quickly you recognize this behavior, you may be able to experience something we call "zero-steer."
As soon as the oversteer initiates, you can roll on the power. If you're quick enough, you'll barely need to correct your steering input (counter-steer) as your throttle input will send load to the rear, reducing front grip. This reduction of front grip stops the oversteer, and you may end up with "zero-steer" where the steering wheel is in the dead center position and the car is turning around the corner almost by itself. At this point, you're simply steering with the gas pedal. More gas steers towards the outside of the turn, less gas steers towards the inside of the turn, and maintaining throttle keeps you on your current path. This is not only the fastest way around the corner, it's also the easiest on your tires. Unfortunately, even for the best of drivers, it's not something you'll experience every corner, but it's sure nice when you do.
Now, assuming you're not quite quick enough and you catch the oversteer a little late, you'll need to make a slight counter-steer correction. This is extremely fast, and extremely minor. We're not drifting, we're not going around the corner with the steering wheel turned in the opposite direction. Simply reduce your steering input (or even temporarily steer in the opposite direction for a split second) and slowly get on to power. Things will quickly sort themselves out and you'll be going around the turn with very neutral handling. Continue rolling on the power, but don't accelerate too much! You'll just end up with understeer again.
As you unwind the wheel and start exiting the corner, you can accelerate more and more. When the wheel is almost straight, you can fully accelerate. It is for this reason that we want to get the car rotated early. The more turning we do at the beginning of the corner, the less we have to do at the end, which means we spend more time on the gas, and less time steering.
I THINK THAT MIGHT BE A BIT BEYOND MY SKILL LEVEL
If this oversteer / zero-steer situation has you scared, or you don't feel that you will be able to recognize the oversteer soon enough, there is absolutely no reason that you ever need to be in this situation. The only way for this to happen is by trail braking too much. This means your brake release continued too far in to the beginning of the corner.
To assure that this doesn't happen to you, simply finish your brake release in a straight line, and start your sensitive application of throttle at turn-in. As you get more and more comfortable, you can try trail braking a little at a time. Do your brake release 1% in to the corner, then 2%, then 5%, etc. Eventually, as you get more confident, you'll find yourself trail braking the first 10% of most corners. Please, PLEASE, keep in mind that "trail braking" is NOT actual braking. This is simply combining your brake release with your turn-in. If you're actually doing any kind of real STOPPING during your turn-in, you are asking for trouble!
THAT'S GREAT AND ALL, BUT I SCREWED UP AND THE CAR IS UNDERSTEERING AS USUAL. NOW WHAT?
When you can't prevent understeer, you can eliminate it mid-corner. Doing so properly is essential, as improperly dealing with understeer is the most dangerous thing you can do, and is responsible for most accidents at the track. "But I thought understeer was safe!?" Well, it's not.
THE MOST COMMON, YET COMPLETELY UNKOWN MISTAKE WITH UNDERSTEER
Before we can talk about eliminating understeer mid-corner, we first need to understand the common mistake that most people make to get them in to really bad situations in the first place. This problem is turning the wheel MORE once the car has started to understeer.
When you think about it, it makes sense. If you want the car to turn more, you turn the wheel more, right? Wrong. What?! If you've asked your tires to turn a certain amount, and they can't, how is asking them to turn even more going to help anything?
An example of this would be in a gym. A man is bench-pressing 200 pounds. He almost has the barbell all the way up, but he's struggling. Then his friend comes over and adds another 20 pounds of weight to his barbell. In this situation, there is no way that the man will be able to lift the 220 pounds, instead, he'll probably drop the weight on top of himself. This is no different with your car, all that will happen is it will understeer more and start to drive completely off the road.
GOT IT. SO NOW WHAT?
So, your car is starting to understeer in a corner. You catch yourself right before you instinctively add more steering. Now instead of having a serious understeer problem, you have options:
1) Reduce your steering input (turn less)
2) Reduce your throttle input (decelerate)
The first option is important to consider. Many times, maintaining your current speed with just a little less steering input is all that is needed to reduce your understeer. If doing so will still allow you to make the corner, you're golden. If it's clear that you're going to drive off the road at your current radius, you move to option #2.
Option #2 has to be dealt with very carefully. As we know, decelerating will send load to the front, increasing front grip. This is a good thing, but too much, too quickly, will cause oversteer. For this reason, you need to be very gradual and sensitive. Lift slowly off the gas. With 10% less throttle will you make the corner? 20%? 30%? Are things really bad? Maybe you need to let off completely, or even brake. That's OK, as long as you do it gradually and smoothly. If you simply lift off the gas and step on the brake you will cause oversteer that is so quick and so violent, you will spin, and exit the track sideways or backwards, guaranteed.
SO UNDERSTEER IS DANGEROUS, AND OVERSTEER ISN'T? THAT SEEMS PRETTY BACKWARDS
Oversteer can be dangerous, but unlike understeer, there are two major kinds of oversteer. There's controllable oversteer, and uncontrollable oversteer. The oversteer you'll experience from trail braking for example, is easily controllable because it's gradual and you're expecting it.
Another kind of equally controllable oversteer is power-on oversteer. This is possibly the easiest kind of oversteer to correct. You got on the gas too hard, too soon, and the rear tires are spinning? Let off. Your problem is gone. The only way to spin out or crash as the result of power-on oversteer is to try to be a drifting, power-sliding, hero that doesn't want to lose a few tenths of a second letting off the gas and regaining traction. As soon as you feel that you've induced that kind of oversteer, lift your right foot and it goes away. That's all there is to it.
SNAP-OVERSTEER
Now, uncontrollable oversteer almost always comes after bad understeer and is commonly referred to as snap-oversteer. This happens when you improperly deal with understeer, and this is usually what people think about when they hear the word "oversteer." It's scary, and it's usually the only kind of oversteer that most drivers experience.
We'll take a typical understeer example. You've failed to properly load your front suspension and/or you're just entering a corner way too fast. The car begins to understeer. Because you haven't read this post, you turn the wheel more to try to make the car turn more. Now you realize that the car is almost certainly going to go off the track and you're running out of road. The outside of the corner is getting closer and closer. You panic and lift off the gas completely and suddenly, maybe even brake. In a split second you go from having excess steering input with no front grip, to excess steering input with an abundance of front grip. What happens? The car turns like you want it to, and then it keeps turning REALLY fast. You try to react by counter-steering, but by this point, it's already too late. In fact, it was already too late when you lifted 2 seconds ago. You're sideways, then you're backwards, and now you're spinning.
What should you do? Well, if you haven't already, you should be hard on the brakes. In fact, as soon as you went more than about 45 degrees sideways you should have been hard on the brakes. But what do most people do? They don't even get on the brakes until they're going backwards, and even then, sometimes they still don't brake. The net result is going off the track sideways or backwards, which can result in rolling the car or hitting a wall. All of which could have been avoided at that very moment you turned the steering wheel more.
That is truth about understeer.
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Here is some more good information coming from questions in later pages of this thread:
Quote:
Originally Posted by severe
reading this i think i'm always way too jerky with the brakes
I wanted to make a slight clarification here as some people may misunderstand the "smooth" braking technique. When you get ON the brakes, it needs to be forceful, hard, and well, it can be down right jerky. Depending on your brake setup, suspension, aero, etc, the initial half second of braking is when most of the stopping is done. It's extremely intense G's and probably can't be done properly without a good seat and harness. It's also something that most people don't do correctly, as it feels natural to progressively get on to the brakes (rather than basically slam them), but that actually increases your stopping distances, heats your brakes more, and reduces pad and rotor life.
To complicate things a little bit, there is the whole theory of "outrunning the load transfer." This is rarely an issue in any track-worthy cars, but is more important in something like a dirt truck, where you have FEET of suspension travel, not inches, and it can actually take quite a bit of time (second+) for load to actually transfer to the front. In this case, slamming the brakes would instantly lock up the front tires since there is no load on them to do any braking. In an STI, it really shouldn't be an issue, especially not with coilovers.
After this initial braking period, you're easing off the brakes a bit (because at the slower speeds you'd lock up the brakes and/or trigger ABS), and doing your downshifting.
Once your downshifting and braking is done, you get in to the smoothness that is being discussed in my post, which is your brake release. Getting ON is rough, getting OFF is extremely smooth.
Quote:
Originally Posted by Chris05STi
It was like your were in my head! Very good info, makes sense. We should have a Forza 3 meeting online for this!
Indeed. It's actually fun to mess with in Forza. One of the biggest things you can improve in that game is not mashing the joystick all the way to one side. The same concept applies in that game, if you push the joystick all the way to one side (full steering lock) you're asking your tires to turn more than they need to and causing understeer.
Quote:
Originally Posted by severe
well yeah my initial braking is really hard, i found this to help my times sometimes i get a single chirp from the abs kickin in also. i havent been to the track yet but my seat time is mainly in autox and im pretty much learning.
i generally slam them hard right before the turn, but reading your post i realize what i never do is release them smoothly. i just drop the brake pedal and then get my foot on the gas. i dont slam the gas i have a pretty good feel for the throttle and how the car reacts to minute adjustments mid turn.
based on what you wrote though it seems like i should take a split second longer in my brake release. i dont know how practical it will be since our autox setups are generally really tight and technical but its worthwhile to try and see if it'll help my times.
right now i can rotate the car a tiny bit with just throttle if i have the dif set to open, and it has some very slight understeer if i'm accelerating through the turn 1 notch up.
btw this has been on my mind, im generally screeching my tires around the entire course. i keep wondering if this is slowing me down or not. its right at the threshold usually i.e. if i remove a very small amount of steering input the screech goes away. i noticed most other guys aren't so aggresive though (though most of them also have rwd)
Two things here. First, this obviously matters a lot more at the track than at an auto cross, but the concept can still be applied. No matter what corner you're talking, a little trail braking will benefit your Subaru. It's just going to be an even quicker brake release in auto x because you brake considerably less and you're not going fast enough to be able to really get on the pedal hard without the ABS coming on.
As for tire screech, try not to rely on that. It's more of a crutch than anything. Really good r-compounds and any slick are completely silent. You don't hear any noise at all until you're backwards. The same goes with lockup / ABS, they don't chirp, you're just see silent tire smoke in your rear view (or in front of you in an open wheel car ).
The key is to feel that understeer coming on BEFORE the tires have to tell you about it. First, because if you correct it really early or avoid it altogether, you'll go much faster. The second reason is obviously as you get better tires you'll stop getting that audible warning. Now, with street tires and street suspension, you still have plenty of time to correct if you wait too long because everything is somewhat in slow motion. If you go to a stiffer, lighter car with stickier tires, everything happens much faster.
Quote:
Originally Posted by santacruz02
Ben, I'd assume the size or width of the front tires makes a difference as well. Like possibly understeer was cause from not having enough tire to pavement?
This actually makes no difference, unless you're suggesting running a DIFFERENT size tire in the front versus the rear. Whether you have 225's on all four corners or 315's you're still going to have identical understeer characteristics basically. The only difference is you'll get it at a slightly higher speed, but when the grip is still going to give up at the same point in the same fashion.
When you see cars with wider tires in the back than the front, they do this to artificially reduce front grip to compensate for oversteer problems. This is particularly noticeable in a Porsche.
You can actually mess with this in the opposite direction with a Subaru and it's kind of fun. Like running 245's in the front and 225's in the back, assuming you can find a tire with the same overall diameter as to not slowly destroy your center diff. Another way to toy with this is to run new tires on the front and used tires on the rear. I used to do this quite a bit, but just know that if you trail brake now, you'll DEFINITELY get oversteer.
Also, please keep in mind when I'm talking about new and used tires I'm talking about race tires, so the difference at most is 2/32's tire depth. If you put new street tires and almost bald street tires you'd probably have a 5/32's difference which isn't so great for your center diff.
Last but not least, and the easiest thing to adjust, is your tire pressures. Running more pressure in the rear than the front will also help make the car more neutral, or more oversteer prone after aggressive trail braking.
Obviously you can adjust suspension settings, swaybar settings, etc, but I like to go to them last for the fine tuning. I'll first start out with what makes the biggest difference (tires), then move on to aero (adjust rear downforce), and then move on to the suspension when the car is close to my liking.
A lot of people ask me why I run a considerably bigger front splitter than rear wing. Well, going back to our most basic load transfer example, the bigger splitter makes 400-500 pounds of downforce (front grip) versus the 300-350 that the rear wing makes (rear grip). The net result is more front grip than rear, which in a perfectly neutral car would cause oversteer, but in a Subaru just makes it more neutral.
Next time you see a Subaru at the track with a 10-foot wide wing raised to roof level and a little v-limited lip spoiler, you'll probably laugh now that you understand what he's actually done to his car.
Quote:
Originally Posted by thundercamel
I wonder this also. I use the tire squeal to know to not push it any harder, and keep it squealing through the turn (on a track). I had just a little squeal the first time, but I've been pushing it louder the last 2 times.
The squeal is your car not wanting to turn, and you either giving it more gas or more steering input. Now, depending on the tires, this squeal could be AFTER it's already understeering pretty badly, or when it's just starting. This is why I tell people not to really use the noise as their indicator.
Now, assuming this noise is the start of understeer for you, hearing the noise isn't terrible, but you could actually go faster if you got the car to rotate more initially before getting to power. The squeal would go away, you'd be on the gas sooner, and you'd have a higher exit speed. Depending on the corner, this may be almost impossible, especially in auto x since it's all understeery, slow, tight corners. Still, brake a little later and get some good trail braking in and you may find that you can still rotate the car before the apex even in those little 40mph corners that seem impossible to get through without plowing.
Quote:
Originally Posted by GotSTI?
I have had 8 hours of track time. 4 hours of class time. All of this was at Watkins Glen. Since I was new to it I was a novice. Still I was one of the fastest cars on the track rarely getting passed my first trip there and never getting passed my second trip there. Needless to say, I started getting Mario Andretti complex... thinking I was better than I was.
When I was at the track I heard people talking about late braking and I kept saying to myself I know these Brembos can handle me doing that. My first instructor had me do a lot of early braking whereas the second one did not. That's where I started to get into some trouble. I saw a lot of the RWD cars braking realllly early. Which made me want to brake realllly late. Quite honestly, this practice had me focusing so hard on timing the braking I wasn't thinking about my shifting and corner entry well. So, I hit the grass and got high up the curbing a couple times. This cost me a few extra track sessions before my instructor let me drive solo.
I learned to practice shifting smoothly on the straights so it would be better for the turns. It was too tempting to smash through gears on the straight away when you'd see a Z06 or something high powered in front of you. When in actuality being smooth and hitting the turn right made a bigger difference in catching those typ of cars.
Now I didn't try trail breaking but found that I could turn in later then other cars. I found that tactic built a lot of confidence / straighter lines through the turns. A LOT less worry about going off track too! I came out most turns a lot faster with this tactic. It was my second instructors advice that seemed to make a huge difference with this. I wonder if you could write your thoughts about this?
Also, I am wondering what is the ideal RPM going into turns for our cars. I found that most of the time I was in 4th and 5th at Watkins Glen (4th for turns). The only time I hit third was with slower cars in front of me. However, that generated a ton of power... or was it that I was just able to get on it earlier into the turns? It was very apparent as I got the point by a lot when this happened.
Lastly, how does heel toe work into this? I'm sure that's a whole other topic but I'd like your explanation on it as I can actually understand you!
Thanks Ben!
What you're describing is late apexing. It's always safer, and generally recommended when you're learning a track. The worst that happens is you go a little slower overall through a corner if you apex way too late. Then when you consider the worst thing that happens when you early apex is you run straight off the track...late apexing is the way to go. Generally speaking, the true apex of a corner is not the same thing as the geometric apex. Most corners require a slightly later apex than the "middle" if that makes sense.
The concept is most often referred to as "slow in, fast out." In other words, you brake a little bit more, you turn in a little bit later, but then you can get on the power really hard on the way out because you got most of your turning done in the first half of the corner. As you get more comfortable with trail braking, you can take that "slow in, fast out" concept and turn it in to "fast in, fast out" but it takes a lot of practice.
Most people, if not specifically told otherwise, will instinctively go "fast in, slow out" because they enter a corner too fast, understeer, scrub speed in the corner, and then get on the gas late at the exit. If you compare your "slow in, fast out" approach with their "fast in, slow out" you'll always be faster, and that's what you were seeing at the track.
Once you are 100% comfortable with the track (you know the line PERFECTLy) and you are 100% comfortable with your car and your driving, you can begin to try some trail braking. Essentially, this lets you carry more speed in to the corner while also reducing understeer. Yes, you can actually go faster and turn more. Thus the "fast in, fast out" principle.
On to RPM range for entering corners. I'd say 4000-5000 RPM. This gives you enough revs to let the gear wind out and not have to shift in a corner (bad!). On the flip side, I'd recommend shifting around 6500. There is no need to wind it all the way out to 7200 unless you're on a track where the end of a straight is just perfectly at 7200 and it would be slower to upshift and immediately downshift. Otherwise, you're being nicer to your motor and actually staying in a better power band (on most turbos). For example, on the engine I'm building I'll be shifting around 7000-7500 even though it's good for 8000-8500. There is just no reason to tempt fate or excessively stress components like that for little to no gain.
Finally, heal toe. Your heal-toe is done during phase 2 of braking. Phase 1 would be your primary stopping right at the beginning. Phase 2 is the rest of the stopping you need to do to make the corner, as well as your downshifting. Phase 3 is your brake release.
The reason for heal toe is that during phase 2 your right foot is on the brake, but you also need to hit the gas to blip the throttle when downshifting (for a rev-matched, smooth shift). There are two methods for heal toe, one is actual heal-toe (which I prefer, but most people don't) where you rotate your foot in such a way that your toes are on the brake and your heal hits the gas pedal. The more common way is to toe-toe, where you roll your foot across the pedals so the left side of your foot and your big toe is on the brake, and the right side of your foot hits the gas. This is easier for people with big feet or when pedals are tightly spaced together. For whatever reason, even with my size 12 shoes and fairly narrow pedals, I still prefer to heal toe as I feel it gives me more control over my braking.
Quote:
Originally Posted by TorstenW
Yeah, you're buddy in the Exige that just outbraked you on the inside and is about to claim position, lol.......
ps; Very nice write-up, btw
.
That quote is how to get comfortable with trail braking. When you start applying it in a race setting, you're braking later than that exige, entering the corner faster, and then getting on the power at almost the same time. The net result is usually a 5mph faster entry speed with a 10mph faster exit speed on say an 80mph corner.
That exige that late braked on the inside is off-line and is either going to have to forfeit his position, run in to me, or I'll let him in and watch him overshoot the corner as I pass him again on the exit (most common).
Quote:
Originally Posted by subyalex
AMAZING post, I can't thank you enough or this insight Ben.
Now, if you could, maybe expand on how left foot braking may be able to assist with keeping the car neutral on long sweepers etc?
I learned alot fro this post, and made me realize how much I have to learn.
Some drivers left foot brake, most don't. It's more common in Rally, but you'd be surprised to find that most track drivers don't bother.
When you think about it, what is left foot braking doing? Decelerating mid corner. What would lifting off the gas slightly (20%) in a high speed sweeper be doing? Decelerating mid corner. What's the difference? If done properly, none, but you're not using two feet, and you're not heating up your brakes (not really a concern, but still a valid point).
Left foot braking is more of a "sounds cool" kind of thing to do, but in practice, the results just aren't there (on the track). It's not BAD, but it's not better, and it's generally harder to get comfortable with and is easier to screw up. Once you've gotten comfortable with being very sensitive with your gas pedal getting on the gas, it's not hard to re-use that sensitivity getting off the gas.
I know a few professional drivers that like to do it, and I know about 5 times as many that don't like to do it. It's just personal preference. Personally, I'd recommend not. There are other things you could be learning and concentrating on that would make you go faster .
Quote:
Originally Posted by tyler_sti
One thing I was going to add is that. If one were to left foot brake in lets say a nice long 90-100mph right sweeper like big willow. You're entering the turn at either full or half throttle, at this point if you need to scrub off speed and release off the throttle you might initiate some over steer because the cars is already loaded on its left side at a high rate of speed. It dosen't always happen especially if you have good suspension, but I've found letting off in mid turn can be very dangerous especially without enough down force on the rear. I like to left foot brake because no only does it keep me in boost for the exit, but the weight transfer isn't as severe. IMO
First, even in a stock STI, turn 8 is a 120mph+ corner. If you're lifting or left foot braking at 90-100mph...don't. You should be flat through 8 if you're comfortable doing it. Aim for the inside of 8 and keep the pedal flat, as you get to the end of 8 release your steering and let the car gently glide out to about 1 car width from the outside of the track, do your braking in a straight line for 9, and get back on the gas.
With coilovers and any sort of good tires and/or aero, turn 8 quickly becomes a turn that is more about ***** than car capability.
But as for the left foot braking:
There is no difference in load and/or oversteer characteristics between left foot braking and gently reducing throttle. I'm not telling you to LIFT completely, simply if you're at 100% throttle, back off to 90%. This is exactly the same thing as remaining at 100% throttle and applying 5-10% brakes, but it requires only one foot. If you're getting oversteer lifting in sweepers, you're lifting too much. You could lift less, go faster, and keep things neutral, if that makes sense.
If it's easier for you to control the deceleration with left foot braking, go for it. It's not a bad thing. In regards to the "staying in boost" part of it, you shouldn't be lifting to the point that you fall out of boost anyway. Again, if your lift is that severe, that's why you're getting oversteer. 100% throttle -> 90% or 80% isn't going to drop you out of boost, and you're not going to be waiting for the turbo on the corner exit. The only way that would happen is if you lift completely.
Some of the terms you're using are concerning though:
Quote:
Originally Posted by tyler_sti
You're entering the turn at either full or half throttle
That's a HUGE difference. Which is it? If you're thinking of the gas pedal in increments of "OFF, HALF, and FULL" you'll benefit greatly by changing how you think about the gas pedal. There is a significant difference between even 90% and 100% throttle when you're at the limit, backing off to 50% throttle is like braking in terms of load transfer.
Quote:
Originally Posted by tyler_sti
I've found letting off in mid turn can be very dangerous
Again, letting off or lifting should mean 100% -> 90%, or 70% -> 50%. If you're thinking of letting off as removing your foot from the gas pedal, yes, that is EXTREMELY dangerous.
The problem with Subarus is people can get away with that kind of stuff and develop extremely bad habits. People lift or even brake mid turn, and many times, nothing bad happens. They then start to think that it's OK, and all this crap about driving smoothly and making subtle inputs doesn't apply to them. Then they drive a car that isn't nearly as forgiving (just about anything else besides an Evo or GTR) and have insane oversteer problems and go spinning off the track.
At the absolute LIMIT, a Subaru doesn't behave much differently than those "other" cars that are considerably more sensitive to load transfer and throttle input. However, until you get within about 5% of that limit, it's almost like the rules of driving don't even apply to an STI (they just understeer). In a normal car, these rules start to apply when you get within about 40% of the limit.
__________________
Ben Fried
RealityDesign
- 2008 Silver BMW 135i
- 2010 Team RD #027 Lotus 2-Eleven Race Car
________________________________________
Quote:
Originally Posted by Chris05STi
It was like your were in my head! Very good info, makes sense. We should have a Forza 3 meeting online for this!
Indeed. It's actually fun to mess with in Forza. One of the biggest things you can improve in that game is not mashing the joystick all the way to one side. The same concept applies in that game, if you push the joystick all the way to one side (full steering lock) you're asking your tires to turn more than they need to and causing understeer.
Quote:
Originally Posted by severe
well yeah my initial braking is really hard, i found this to help my times sometimes i get a single chirp from the abs kickin in also. i havent been to the track yet but my seat time is mainly in autox and im pretty much learning.
i generally slam them hard right before the turn, but reading your post i realize what i never do is release them smoothly. i just drop the brake pedal and then get my foot on the gas. i dont slam the gas i have a pretty good feel for the throttle and how the car reacts to minute adjustments mid turn.
based on what you wrote though it seems like i should take a split second longer in my brake release. i dont know how practical it will be since our autox setups are generally really tight and technical but its worthwhile to try and see if it'll help my times.
right now i can rotate the car a tiny bit with just throttle if i have the dif set to open, and it has some very slight understeer if i'm accelerating through the turn 1 notch up.
btw this has been on my mind, im generally screeching my tires around the entire course. i keep wondering if this is slowing me down or not. its right at the threshold usually i.e. if i remove a very small amount of steering input the screech goes away. i noticed most other guys aren't so aggresive though (though most of them also have rwd)
Two things here. First, this obviously matters a lot more at the track than at an auto cross, but the concept can still be applied. No matter what corner you're talking, a little trail braking will benefit your Subaru. It's just going to be an even quicker brake release in auto x because you brake considerably less and you're not going fast enough to be able to really get on the pedal hard without the ABS coming on.
As for tire screech, try not to rely on that. It's more of a crutch than anything. Really good r-compounds and any slick are completely silent. You don't hear any noise at all until you're backwards. The same goes with lockup / ABS, they don't chirp, you're just see silent tire smoke in your rear view (or in front of you in an open wheel car ).
The key is to feel that understeer coming on BEFORE the tires have to tell you about it. First, because if you correct it really early or avoid it altogether, you'll go much faster. The second reason is obviously as you get better tires you'll stop getting that audible warning. Now, with street tires and street suspension, you still have plenty of time to correct if you wait too long because everything is somewhat in slow motion. If you go to a stiffer, lighter car with stickier tires, everything happens much faster.
Quote:
Originally Posted by santacruz02
Ben, I'd assume the size or width of the front tires makes a difference as well. Like possibly understeer was cause from not having enough tire to pavement?
This actually makes no difference, unless you're suggesting running a DIFFERENT size tire in the front versus the rear. Whether you have 225's on all four corners or 315's you're still going to have identical understeer characteristics basically. The only difference is you'll get it at a slightly higher speed, but when the grip is still going to give up at the same point in the same fashion.
When you see cars with wider tires in the back than the front, they do this to artificially reduce front grip to compensate for oversteer problems. This is particularly noticeable in a Porsche.
You can actually mess with this in the opposite direction with a Subaru and it's kind of fun. Like running 245's in the front and 225's in the back, assuming you can find a tire with the same overall diameter as to not slowly destroy your center diff. Another way to toy with this is to run new tires on the front and used tires on the rear. I used to do this quite a bit, but just know that if you trail brake now, you'll DEFINITELY get oversteer.
Also, please keep in mind when I'm talking about new and used tires I'm talking about race tires, so the difference at most is 2/32's tire depth. If you put new street tires and almost bald street tires you'd probably have a 5/32's difference which isn't so great for your center diff.
Last but not least, and the easiest thing to adjust, is your tire pressures. Running more pressure in the rear than the front will also help make the car more neutral, or more oversteer prone after aggressive trail braking.
Obviously you can adjust suspension settings, swaybar settings, etc, but I like to go to them last for the fine tuning. I'll first start out with what makes the biggest difference (tires), then move on to aero (adjust rear downforce), and then move on to the suspension when the car is close to my liking.
A lot of people ask me why I run a considerably bigger front splitter than rear wing. Well, going back to our most basic load transfer example, the bigger splitter makes 400-500 pounds of downforce (front grip) versus the 300-350 that the rear wing makes (rear grip). The net result is more front grip than rear, which in a perfectly neutral car would cause oversteer, but in a Subaru just makes it more neutral.
Next time you see a Subaru at the track with a 10-foot wide wing raised to roof level and a little v-limited lip spoiler, you'll probably laugh now that you understand what he's actually done to his car.
Quote:
Originally Posted by thundercamel
I wonder this also. I use the tire squeal to know to not push it any harder, and keep it squealing through the turn (on a track). I had just a little squeal the first time, but I've been pushing it louder the last 2 times.
The squeal is your car not wanting to turn, and you either giving it more gas or more steering input. Now, depending on the tires, this squeal could be AFTER it's already understeering pretty badly, or when it's just starting. This is why I tell people not to really use the noise as their indicator.
Now, assuming this noise is the start of understeer for you, hearing the noise isn't terrible, but you could actually go faster if you got the car to rotate more initially before getting to power. The squeal would go away, you'd be on the gas sooner, and you'd have a higher exit speed. Depending on the corner, this may be almost impossible, especially in auto x since it's all understeery, slow, tight corners. Still, brake a little later and get some good trail braking in and you may find that you can still rotate the car before the apex even in those little 40mph corners that seem impossible to get through without plowing.
Quote:
Originally Posted by GotSTI?
I have had 8 hours of track time. 4 hours of class time. All of this was at Watkins Glen. Since I was new to it I was a novice. Still I was one of the fastest cars on the track rarely getting passed my first trip there and never getting passed my second trip there. Needless to say, I started getting Mario Andretti complex... thinking I was better than I was.
When I was at the track I heard people talking about late braking and I kept saying to myself I know these Brembos can handle me doing that. My first instructor had me do a lot of early braking whereas the second one did not. That's where I started to get into some trouble. I saw a lot of the RWD cars braking realllly early. Which made me want to brake realllly late. Quite honestly, this practice had me focusing so hard on timing the braking I wasn't thinking about my shifting and corner entry well. So, I hit the grass and got high up the curbing a couple times. This cost me a few extra track sessions before my instructor let me drive solo.
I learned to practice shifting smoothly on the straights so it would be better for the turns. It was too tempting to smash through gears on the straight away when you'd see a Z06 or something high powered in front of you. When in actuality being smooth and hitting the turn right made a bigger difference in catching those typ of cars.
Now I didn't try trail breaking but found that I could turn in later then other cars. I found that tactic built a lot of confidence / straighter lines through the turns. A LOT less worry about going off track too! I came out most turns a lot faster with this tactic. It was my second instructors advice that seemed to make a huge difference with this. I wonder if you could write your thoughts about this?
Also, I am wondering what is the ideal RPM going into turns for our cars. I found that most of the time I was in 4th and 5th at Watkins Glen (4th for turns). The only time I hit third was with slower cars in front of me. However, that generated a ton of power... or was it that I was just able to get on it earlier into the turns? It was very apparent as I got the point by a lot when this happened.
Lastly, how does heel toe work into this? I'm sure that's a whole other topic but I'd like your explanation on it as I can actually understand you!
Thanks Ben!
What you're describing is late apexing. It's always safer, and generally recommended when you're learning a track. The worst that happens is you go a little slower overall through a corner if you apex way too late. Then when you consider the worst thing that happens when you early apex is you run straight off the track...late apexing is the way to go. Generally speaking, the true apex of a corner is not the same thing as the geometric apex. Most corners require a slightly later apex than the "middle" if that makes sense.
The concept is most often referred to as "slow in, fast out." In other words, you brake a little bit more, you turn in a little bit later, but then you can get on the power really hard on the way out because you got most of your turning done in the first half of the corner. As you get more comfortable with trail braking, you can take that "slow in, fast out" concept and turn it in to "fast in, fast out" but it takes a lot of practice.
Most people, if not specifically told otherwise, will instinctively go "fast in, slow out" because they enter a corner too fast, understeer, scrub speed in the corner, and then get on the gas late at the exit. If you compare your "slow in, fast out" approach with their "fast in, slow out" you'll always be faster, and that's what you were seeing at the track.
Once you are 100% comfortable with the track (you know the line PERFECTLy) and you are 100% comfortable with your car and your driving, you can begin to try some trail braking. Essentially, this lets you carry more speed in to the corner while also reducing understeer. Yes, you can actually go faster and turn more. Thus the "fast in, fast out" principle.
On to RPM range for entering corners. I'd say 4000-5000 RPM. This gives you enough revs to let the gear wind out and not have to shift in a corner (bad!). On the flip side, I'd recommend shifting around 6500. There is no need to wind it all the way out to 7200 unless you're on a track where the end of a straight is just perfectly at 7200 and it would be slower to upshift and immediately downshift. Otherwise, you're being nicer to your motor and actually staying in a better power band (on most turbos). For example, on the engine I'm building I'll be shifting around 7000-7500 even though it's good for 8000-8500. There is just no reason to tempt fate or excessively stress components like that for little to no gain.
Finally, heal toe. Your heal-toe is done during phase 2 of braking. Phase 1 would be your primary stopping right at the beginning. Phase 2 is the rest of the stopping you need to do to make the corner, as well as your downshifting. Phase 3 is your brake release.
The reason for heal toe is that during phase 2 your right foot is on the brake, but you also need to hit the gas to blip the throttle when downshifting (for a rev-matched, smooth shift). There are two methods for heal toe, one is actual heal-toe (which I prefer, but most people don't) where you rotate your foot in such a way that your toes are on the brake and your heal hits the gas pedal. The more common way is to toe-toe, where you roll your foot across the pedals so the left side of your foot and your big toe is on the brake, and the right side of your foot hits the gas. This is easier for people with big feet or when pedals are tightly spaced together. For whatever reason, even with my size 12 shoes and fairly narrow pedals, I still prefer to heal toe as I feel it gives me more control over my braking.
Quote:
Originally Posted by TorstenW
Yeah, you're buddy in the Exige that just outbraked you on the inside and is about to claim position, lol.......
ps; Very nice write-up, btw
.
That quote is how to get comfortable with trail braking. When you start applying it in a race setting, you're braking later than that exige, entering the corner faster, and then getting on the power at almost the same time. The net result is usually a 5mph faster entry speed with a 10mph faster exit speed on say an 80mph corner.
That exige that late braked on the inside is off-line and is either going to have to forfeit his position, run in to me, or I'll let him in and watch him overshoot the corner as I pass him again on the exit (most common).
__________________
Ben Fried
RealityDesign
- 2008 Silver BMW 135i
- 2010 Team RD #027 Lotus 2-Eleven Race Car
Quote:
Originally Posted by subyalex
AMAZING post, I can't thank you enough or this insight Ben.
Now, if you could, maybe expand on how left foot braking may be able to assist with keeping the car neutral on long sweepers etc?
I learned alot fro this post, and made me realize how much I have to learn.
Some drivers left foot brake, most don't. It's more common in Rally, but you'd be surprised to find that most track drivers don't bother.
When you think about it, what is left foot braking doing? Decelerating mid corner. What would lifting off the gas slightly (20%) in a high speed sweeper be doing? Decelerating mid corner. What's the difference? If done properly, none, but you're not using two feet, and you're not heating up your brakes (not really a concern, but still a valid point).
Left foot braking is more of a "sounds cool" kind of thing to do, but in practice, the results just aren't there (on the track). It's not BAD, but it's not better, and it's generally harder to get comfortable with and is easier to screw up. Once you've gotten comfortable with being very sensitive with your gas pedal getting on the gas, it's not hard to re-use that sensitivity getting off the gas.
I know a few professional drivers that like to do it, and I know about 5 times as many that don't like to do it. It's just personal preference. Personally, I'd recommend not. There are other things you could be learning and concentrating on that would make you go faster .
__________________
Ben Fried
RealityDesign
- 2008 Silver BMW 135i
- 2010 Team RD #027 Lotus 2-Eleven Race Car
I thought this was worth sharing. long but worthwhile read.
Josh, i guess you remember this, since you replied in the other post
The original posts can be found in this thread here. Great reading.
http://www.iwsti.com/forums/driving-...ndersteer.html
The Real Truth About Understeer
________________________________________
There was a post made recently that supposedly exposed the "truth" about Subaru understeer. In summary, someone on this forum watched a video of a driver saying that driving too smoothly causes understeer, and that the proper way to corner in a Subaru is to violently whip the steering wheel 70 degrees or so on turn in to eliminate understeer.
Now, hopefully, I don't need to tell you that this is a load of crap. However, the fact that someone watched this video and had some sort of epiphany and wanted to share it with others on this forum was REALLY SCARY. I ended up accidentally writing a fairly long post about how to properly enter a corner in a Subaru, and then went off on a somewhat of a tangent about understeer in general. Because of this, I felt it would be a good idea to take what I already wrote and expand a little bit. It should help 98% of the drivers out there, as understeer is probably the most commonly misunderstood driving concept there is.
If you go to the track, you should read this. Even if you think you know everything there is to know about understeer, you'll probably learn something.
The Real Truth About Understeer
What exactly is understeer? In purely technical terms, it's a lack of front tire grip. But what does that actually mean? What causes it? How can you get rid of it mid-corner? How can you avoid it altogether? And most importantly, why is it actually MORE dangerous than oversteer?
First, let's understand exactly what understeer means. When you enter a corner and the car begins to "push" toward the outside of the turn, you're experiencing understeer. You've dialed in the correct amount of steering input (turned the wheel the correct amount) but the car is turning less than it should.
REASONS FOR UNDERSTEER
So, why does this happen? This happens because your rear tires have more grip than your front tires. When you begin to turn, instead of the front tires gripping on the road, they slide. This can happen for one of three basic reasons:
1) You've entered a corner too fast (surprisingly, this isn't usually the problem!)
2) You're trying to turn too much (you've actually asked the tires to do more than you need them to do)
3) Your brake and/or throttle inputs haven't loaded the front suspension properly (this is your problem, 95% of the time)
Let's discuss #3 first, as this is the most common cause of understeer. To understand load transfer, also commonly (and incorrectly) referred to as weight transfer, perform this simple exercise:
Place your hand face-down on the table/desk in front of you. Slide it forward on the table. Your hand slides easily because you have very little load forcing it on the table. Now stand up, and lean on your hand. While leaning on your hand, try to slide it forward. It doesn't slide. This is because you have a lot of load on your hand. The same exact thing is constantly happening with your tires. When you have load on your tires, they grip. When you don't, they slide.
Simply put, when you accelerate, load is transfered rearward. When you decelerate, load is transfered forward. Deceleration doesn't necessarily mean braking, as coasting or even easing off the throttle will cause the vehicle to slow down (decelerate). This is even more dramatic when driving up hill, as the slightest decrease in throttle input causes the car to decelerate significantly.
BRAKE RELEASE
So, we know that understeer is caused by a lack of front grip, and we know that we can increase front grip by transferring load to the front of the car. So as long as we decelerate before every corner, we'll never understeer ever again! Right? Well, it's not quite that easy.
The way in which we brake and accelerate, or more importantly, the way in which we release the brakes and roll on the throttle, determines how the load is transfered, how much load is transfered, and most importantly, how much load actually STAYS in the front of the car.
If we brake very hard, a lot of load is sent to the front. However, if we abruptly lift off the brakes and get back on to the throttle, all of that load goes right back to the rear. In fact, when you're accelerating hard, the front tires have so little load that they're barely making contact with the ground. Just think about how well your car would steer if you were doing a wheelie through the turn.
So, how can we accelerate through a corner and still maintain a healthy amount of front load and grip? The answer is proper brake release, followed by sensitive throttle input. Ideally, a passenger should not be able to tell when you've gotten off the brakes and on to the gas.
To do this, you need to revise your braking strategy. Braking "late" or "diving" in to corners and getting on the power early may seem like the fastest way around the track, but this usually slows people down. There is a way to brake late and get on to the throttle sooner, but it can't happen until you've mastered proper brake release.
To start out, brake 10-20% earlier than you normally would. Try to get all of your braking done well before the corner. At this point, you should feel like you broke too early. You have a quarter to half a second of time, which feels like an eternity, in which you don't need to be slowing down anymore, but you don't need to be turning yet. During this "dead space" you focus on one thing, and one thing only: brake release. This is your time to gradually release the brakes and begin to turn in. As you get comfortable with this, you can begin braking where you normally did before, combining this smooth brake release with your turn-in, often referred to as "trail braking." You then need to follow this up with an equally smooth and gradual application of throttle. Smashing on the gas at this point will ruin all of the work you've done up this point with your brake release.
If done correctly, one of two things will happen depending on a variety of factors:
1) The car will be perfectly neutral through the turn and will turn exactly the same amount as you turn the steering wheel.
2) The car will oversteer slightly, turning more than you turn the steering wheel.
No explanation is needed for #1. You're good to go. Congratulations, for the first time ever, your Subaru isn't fighting you through a turn.
OVERSTEER AND "ZERO-STEER"
Next, we have situation #2. This is a GOOD situation to be in, do not be afraid! Clearly, hell has frozen over, as your Subaru is oversteering. How could this have happened? The answer is you've successfully trail braked to the point that you actually have so much front grip that your car is able to turn more than you asked of it. Depending on how quickly you recognize this behavior, you may be able to experience something we call "zero-steer."
As soon as the oversteer initiates, you can roll on the power. If you're quick enough, you'll barely need to correct your steering input (counter-steer) as your throttle input will send load to the rear, reducing front grip. This reduction of front grip stops the oversteer, and you may end up with "zero-steer" where the steering wheel is in the dead center position and the car is turning around the corner almost by itself. At this point, you're simply steering with the gas pedal. More gas steers towards the outside of the turn, less gas steers towards the inside of the turn, and maintaining throttle keeps you on your current path. This is not only the fastest way around the corner, it's also the easiest on your tires. Unfortunately, even for the best of drivers, it's not something you'll experience every corner, but it's sure nice when you do.
Now, assuming you're not quite quick enough and you catch the oversteer a little late, you'll need to make a slight counter-steer correction. This is extremely fast, and extremely minor. We're not drifting, we're not going around the corner with the steering wheel turned in the opposite direction. Simply reduce your steering input (or even temporarily steer in the opposite direction for a split second) and slowly get on to power. Things will quickly sort themselves out and you'll be going around the turn with very neutral handling. Continue rolling on the power, but don't accelerate too much! You'll just end up with understeer again.
As you unwind the wheel and start exiting the corner, you can accelerate more and more. When the wheel is almost straight, you can fully accelerate. It is for this reason that we want to get the car rotated early. The more turning we do at the beginning of the corner, the less we have to do at the end, which means we spend more time on the gas, and less time steering.
I THINK THAT MIGHT BE A BIT BEYOND MY SKILL LEVEL
If this oversteer / zero-steer situation has you scared, or you don't feel that you will be able to recognize the oversteer soon enough, there is absolutely no reason that you ever need to be in this situation. The only way for this to happen is by trail braking too much. This means your brake release continued too far in to the beginning of the corner.
To assure that this doesn't happen to you, simply finish your brake release in a straight line, and start your sensitive application of throttle at turn-in. As you get more and more comfortable, you can try trail braking a little at a time. Do your brake release 1% in to the corner, then 2%, then 5%, etc. Eventually, as you get more confident, you'll find yourself trail braking the first 10% of most corners. Please, PLEASE, keep in mind that "trail braking" is NOT actual braking. This is simply combining your brake release with your turn-in. If you're actually doing any kind of real STOPPING during your turn-in, you are asking for trouble!
THAT'S GREAT AND ALL, BUT I SCREWED UP AND THE CAR IS UNDERSTEERING AS USUAL. NOW WHAT?
When you can't prevent understeer, you can eliminate it mid-corner. Doing so properly is essential, as improperly dealing with understeer is the most dangerous thing you can do, and is responsible for most accidents at the track. "But I thought understeer was safe!?" Well, it's not.
THE MOST COMMON, YET COMPLETELY UNKOWN MISTAKE WITH UNDERSTEER
Before we can talk about eliminating understeer mid-corner, we first need to understand the common mistake that most people make to get them in to really bad situations in the first place. This problem is turning the wheel MORE once the car has started to understeer.
When you think about it, it makes sense. If you want the car to turn more, you turn the wheel more, right? Wrong. What?! If you've asked your tires to turn a certain amount, and they can't, how is asking them to turn even more going to help anything?
An example of this would be in a gym. A man is bench-pressing 200 pounds. He almost has the barbell all the way up, but he's struggling. Then his friend comes over and adds another 20 pounds of weight to his barbell. In this situation, there is no way that the man will be able to lift the 220 pounds, instead, he'll probably drop the weight on top of himself. This is no different with your car, all that will happen is it will understeer more and start to drive completely off the road.
GOT IT. SO NOW WHAT?
So, your car is starting to understeer in a corner. You catch yourself right before you instinctively add more steering. Now instead of having a serious understeer problem, you have options:
1) Reduce your steering input (turn less)
2) Reduce your throttle input (decelerate)
The first option is important to consider. Many times, maintaining your current speed with just a little less steering input is all that is needed to reduce your understeer. If doing so will still allow you to make the corner, you're golden. If it's clear that you're going to drive off the road at your current radius, you move to option #2.
Option #2 has to be dealt with very carefully. As we know, decelerating will send load to the front, increasing front grip. This is a good thing, but too much, too quickly, will cause oversteer. For this reason, you need to be very gradual and sensitive. Lift slowly off the gas. With 10% less throttle will you make the corner? 20%? 30%? Are things really bad? Maybe you need to let off completely, or even brake. That's OK, as long as you do it gradually and smoothly. If you simply lift off the gas and step on the brake you will cause oversteer that is so quick and so violent, you will spin, and exit the track sideways or backwards, guaranteed.
SO UNDERSTEER IS DANGEROUS, AND OVERSTEER ISN'T? THAT SEEMS PRETTY BACKWARDS
Oversteer can be dangerous, but unlike understeer, there are two major kinds of oversteer. There's controllable oversteer, and uncontrollable oversteer. The oversteer you'll experience from trail braking for example, is easily controllable because it's gradual and you're expecting it.
Another kind of equally controllable oversteer is power-on oversteer. This is possibly the easiest kind of oversteer to correct. You got on the gas too hard, too soon, and the rear tires are spinning? Let off. Your problem is gone. The only way to spin out or crash as the result of power-on oversteer is to try to be a drifting, power-sliding, hero that doesn't want to lose a few tenths of a second letting off the gas and regaining traction. As soon as you feel that you've induced that kind of oversteer, lift your right foot and it goes away. That's all there is to it.
SNAP-OVERSTEER
Now, uncontrollable oversteer almost always comes after bad understeer and is commonly referred to as snap-oversteer. This happens when you improperly deal with understeer, and this is usually what people think about when they hear the word "oversteer." It's scary, and it's usually the only kind of oversteer that most drivers experience.
We'll take a typical understeer example. You've failed to properly load your front suspension and/or you're just entering a corner way too fast. The car begins to understeer. Because you haven't read this post, you turn the wheel more to try to make the car turn more. Now you realize that the car is almost certainly going to go off the track and you're running out of road. The outside of the corner is getting closer and closer. You panic and lift off the gas completely and suddenly, maybe even brake. In a split second you go from having excess steering input with no front grip, to excess steering input with an abundance of front grip. What happens? The car turns like you want it to, and then it keeps turning REALLY fast. You try to react by counter-steering, but by this point, it's already too late. In fact, it was already too late when you lifted 2 seconds ago. You're sideways, then you're backwards, and now you're spinning.
What should you do? Well, if you haven't already, you should be hard on the brakes. In fact, as soon as you went more than about 45 degrees sideways you should have been hard on the brakes. But what do most people do? They don't even get on the brakes until they're going backwards, and even then, sometimes they still don't brake. The net result is going off the track sideways or backwards, which can result in rolling the car or hitting a wall. All of which could have been avoided at that very moment you turned the steering wheel more.
That is truth about understeer.
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Here is some more good information coming from questions in later pages of this thread:
Quote:
Originally Posted by severe
reading this i think i'm always way too jerky with the brakes
I wanted to make a slight clarification here as some people may misunderstand the "smooth" braking technique. When you get ON the brakes, it needs to be forceful, hard, and well, it can be down right jerky. Depending on your brake setup, suspension, aero, etc, the initial half second of braking is when most of the stopping is done. It's extremely intense G's and probably can't be done properly without a good seat and harness. It's also something that most people don't do correctly, as it feels natural to progressively get on to the brakes (rather than basically slam them), but that actually increases your stopping distances, heats your brakes more, and reduces pad and rotor life.
To complicate things a little bit, there is the whole theory of "outrunning the load transfer." This is rarely an issue in any track-worthy cars, but is more important in something like a dirt truck, where you have FEET of suspension travel, not inches, and it can actually take quite a bit of time (second+) for load to actually transfer to the front. In this case, slamming the brakes would instantly lock up the front tires since there is no load on them to do any braking. In an STI, it really shouldn't be an issue, especially not with coilovers.
After this initial braking period, you're easing off the brakes a bit (because at the slower speeds you'd lock up the brakes and/or trigger ABS), and doing your downshifting.
Once your downshifting and braking is done, you get in to the smoothness that is being discussed in my post, which is your brake release. Getting ON is rough, getting OFF is extremely smooth.
Quote:
Originally Posted by Chris05STi
It was like your were in my head! Very good info, makes sense. We should have a Forza 3 meeting online for this!
Indeed. It's actually fun to mess with in Forza. One of the biggest things you can improve in that game is not mashing the joystick all the way to one side. The same concept applies in that game, if you push the joystick all the way to one side (full steering lock) you're asking your tires to turn more than they need to and causing understeer.
Quote:
Originally Posted by severe
well yeah my initial braking is really hard, i found this to help my times sometimes i get a single chirp from the abs kickin in also. i havent been to the track yet but my seat time is mainly in autox and im pretty much learning.
i generally slam them hard right before the turn, but reading your post i realize what i never do is release them smoothly. i just drop the brake pedal and then get my foot on the gas. i dont slam the gas i have a pretty good feel for the throttle and how the car reacts to minute adjustments mid turn.
based on what you wrote though it seems like i should take a split second longer in my brake release. i dont know how practical it will be since our autox setups are generally really tight and technical but its worthwhile to try and see if it'll help my times.
right now i can rotate the car a tiny bit with just throttle if i have the dif set to open, and it has some very slight understeer if i'm accelerating through the turn 1 notch up.
btw this has been on my mind, im generally screeching my tires around the entire course. i keep wondering if this is slowing me down or not. its right at the threshold usually i.e. if i remove a very small amount of steering input the screech goes away. i noticed most other guys aren't so aggresive though (though most of them also have rwd)
Two things here. First, this obviously matters a lot more at the track than at an auto cross, but the concept can still be applied. No matter what corner you're talking, a little trail braking will benefit your Subaru. It's just going to be an even quicker brake release in auto x because you brake considerably less and you're not going fast enough to be able to really get on the pedal hard without the ABS coming on.
As for tire screech, try not to rely on that. It's more of a crutch than anything. Really good r-compounds and any slick are completely silent. You don't hear any noise at all until you're backwards. The same goes with lockup / ABS, they don't chirp, you're just see silent tire smoke in your rear view (or in front of you in an open wheel car ).
The key is to feel that understeer coming on BEFORE the tires have to tell you about it. First, because if you correct it really early or avoid it altogether, you'll go much faster. The second reason is obviously as you get better tires you'll stop getting that audible warning. Now, with street tires and street suspension, you still have plenty of time to correct if you wait too long because everything is somewhat in slow motion. If you go to a stiffer, lighter car with stickier tires, everything happens much faster.
Quote:
Originally Posted by santacruz02
Ben, I'd assume the size or width of the front tires makes a difference as well. Like possibly understeer was cause from not having enough tire to pavement?
This actually makes no difference, unless you're suggesting running a DIFFERENT size tire in the front versus the rear. Whether you have 225's on all four corners or 315's you're still going to have identical understeer characteristics basically. The only difference is you'll get it at a slightly higher speed, but when the grip is still going to give up at the same point in the same fashion.
When you see cars with wider tires in the back than the front, they do this to artificially reduce front grip to compensate for oversteer problems. This is particularly noticeable in a Porsche.
You can actually mess with this in the opposite direction with a Subaru and it's kind of fun. Like running 245's in the front and 225's in the back, assuming you can find a tire with the same overall diameter as to not slowly destroy your center diff. Another way to toy with this is to run new tires on the front and used tires on the rear. I used to do this quite a bit, but just know that if you trail brake now, you'll DEFINITELY get oversteer.
Also, please keep in mind when I'm talking about new and used tires I'm talking about race tires, so the difference at most is 2/32's tire depth. If you put new street tires and almost bald street tires you'd probably have a 5/32's difference which isn't so great for your center diff.
Last but not least, and the easiest thing to adjust, is your tire pressures. Running more pressure in the rear than the front will also help make the car more neutral, or more oversteer prone after aggressive trail braking.
Obviously you can adjust suspension settings, swaybar settings, etc, but I like to go to them last for the fine tuning. I'll first start out with what makes the biggest difference (tires), then move on to aero (adjust rear downforce), and then move on to the suspension when the car is close to my liking.
A lot of people ask me why I run a considerably bigger front splitter than rear wing. Well, going back to our most basic load transfer example, the bigger splitter makes 400-500 pounds of downforce (front grip) versus the 300-350 that the rear wing makes (rear grip). The net result is more front grip than rear, which in a perfectly neutral car would cause oversteer, but in a Subaru just makes it more neutral.
Next time you see a Subaru at the track with a 10-foot wide wing raised to roof level and a little v-limited lip spoiler, you'll probably laugh now that you understand what he's actually done to his car.
Quote:
Originally Posted by thundercamel
I wonder this also. I use the tire squeal to know to not push it any harder, and keep it squealing through the turn (on a track). I had just a little squeal the first time, but I've been pushing it louder the last 2 times.
The squeal is your car not wanting to turn, and you either giving it more gas or more steering input. Now, depending on the tires, this squeal could be AFTER it's already understeering pretty badly, or when it's just starting. This is why I tell people not to really use the noise as their indicator.
Now, assuming this noise is the start of understeer for you, hearing the noise isn't terrible, but you could actually go faster if you got the car to rotate more initially before getting to power. The squeal would go away, you'd be on the gas sooner, and you'd have a higher exit speed. Depending on the corner, this may be almost impossible, especially in auto x since it's all understeery, slow, tight corners. Still, brake a little later and get some good trail braking in and you may find that you can still rotate the car before the apex even in those little 40mph corners that seem impossible to get through without plowing.
Quote:
Originally Posted by GotSTI?
I have had 8 hours of track time. 4 hours of class time. All of this was at Watkins Glen. Since I was new to it I was a novice. Still I was one of the fastest cars on the track rarely getting passed my first trip there and never getting passed my second trip there. Needless to say, I started getting Mario Andretti complex... thinking I was better than I was.
When I was at the track I heard people talking about late braking and I kept saying to myself I know these Brembos can handle me doing that. My first instructor had me do a lot of early braking whereas the second one did not. That's where I started to get into some trouble. I saw a lot of the RWD cars braking realllly early. Which made me want to brake realllly late. Quite honestly, this practice had me focusing so hard on timing the braking I wasn't thinking about my shifting and corner entry well. So, I hit the grass and got high up the curbing a couple times. This cost me a few extra track sessions before my instructor let me drive solo.
I learned to practice shifting smoothly on the straights so it would be better for the turns. It was too tempting to smash through gears on the straight away when you'd see a Z06 or something high powered in front of you. When in actuality being smooth and hitting the turn right made a bigger difference in catching those typ of cars.
Now I didn't try trail breaking but found that I could turn in later then other cars. I found that tactic built a lot of confidence / straighter lines through the turns. A LOT less worry about going off track too! I came out most turns a lot faster with this tactic. It was my second instructors advice that seemed to make a huge difference with this. I wonder if you could write your thoughts about this?
Also, I am wondering what is the ideal RPM going into turns for our cars. I found that most of the time I was in 4th and 5th at Watkins Glen (4th for turns). The only time I hit third was with slower cars in front of me. However, that generated a ton of power... or was it that I was just able to get on it earlier into the turns? It was very apparent as I got the point by a lot when this happened.
Lastly, how does heel toe work into this? I'm sure that's a whole other topic but I'd like your explanation on it as I can actually understand you!
Thanks Ben!
What you're describing is late apexing. It's always safer, and generally recommended when you're learning a track. The worst that happens is you go a little slower overall through a corner if you apex way too late. Then when you consider the worst thing that happens when you early apex is you run straight off the track...late apexing is the way to go. Generally speaking, the true apex of a corner is not the same thing as the geometric apex. Most corners require a slightly later apex than the "middle" if that makes sense.
The concept is most often referred to as "slow in, fast out." In other words, you brake a little bit more, you turn in a little bit later, but then you can get on the power really hard on the way out because you got most of your turning done in the first half of the corner. As you get more comfortable with trail braking, you can take that "slow in, fast out" concept and turn it in to "fast in, fast out" but it takes a lot of practice.
Most people, if not specifically told otherwise, will instinctively go "fast in, slow out" because they enter a corner too fast, understeer, scrub speed in the corner, and then get on the gas late at the exit. If you compare your "slow in, fast out" approach with their "fast in, slow out" you'll always be faster, and that's what you were seeing at the track.
Once you are 100% comfortable with the track (you know the line PERFECTLy) and you are 100% comfortable with your car and your driving, you can begin to try some trail braking. Essentially, this lets you carry more speed in to the corner while also reducing understeer. Yes, you can actually go faster and turn more. Thus the "fast in, fast out" principle.
On to RPM range for entering corners. I'd say 4000-5000 RPM. This gives you enough revs to let the gear wind out and not have to shift in a corner (bad!). On the flip side, I'd recommend shifting around 6500. There is no need to wind it all the way out to 7200 unless you're on a track where the end of a straight is just perfectly at 7200 and it would be slower to upshift and immediately downshift. Otherwise, you're being nicer to your motor and actually staying in a better power band (on most turbos). For example, on the engine I'm building I'll be shifting around 7000-7500 even though it's good for 8000-8500. There is just no reason to tempt fate or excessively stress components like that for little to no gain.
Finally, heal toe. Your heal-toe is done during phase 2 of braking. Phase 1 would be your primary stopping right at the beginning. Phase 2 is the rest of the stopping you need to do to make the corner, as well as your downshifting. Phase 3 is your brake release.
The reason for heal toe is that during phase 2 your right foot is on the brake, but you also need to hit the gas to blip the throttle when downshifting (for a rev-matched, smooth shift). There are two methods for heal toe, one is actual heal-toe (which I prefer, but most people don't) where you rotate your foot in such a way that your toes are on the brake and your heal hits the gas pedal. The more common way is to toe-toe, where you roll your foot across the pedals so the left side of your foot and your big toe is on the brake, and the right side of your foot hits the gas. This is easier for people with big feet or when pedals are tightly spaced together. For whatever reason, even with my size 12 shoes and fairly narrow pedals, I still prefer to heal toe as I feel it gives me more control over my braking.
Quote:
Originally Posted by TorstenW
Yeah, you're buddy in the Exige that just outbraked you on the inside and is about to claim position, lol.......
ps; Very nice write-up, btw
.
That quote is how to get comfortable with trail braking. When you start applying it in a race setting, you're braking later than that exige, entering the corner faster, and then getting on the power at almost the same time. The net result is usually a 5mph faster entry speed with a 10mph faster exit speed on say an 80mph corner.
That exige that late braked on the inside is off-line and is either going to have to forfeit his position, run in to me, or I'll let him in and watch him overshoot the corner as I pass him again on the exit (most common).
Quote:
Originally Posted by subyalex
AMAZING post, I can't thank you enough or this insight Ben.
Now, if you could, maybe expand on how left foot braking may be able to assist with keeping the car neutral on long sweepers etc?
I learned alot fro this post, and made me realize how much I have to learn.
Some drivers left foot brake, most don't. It's more common in Rally, but you'd be surprised to find that most track drivers don't bother.
When you think about it, what is left foot braking doing? Decelerating mid corner. What would lifting off the gas slightly (20%) in a high speed sweeper be doing? Decelerating mid corner. What's the difference? If done properly, none, but you're not using two feet, and you're not heating up your brakes (not really a concern, but still a valid point).
Left foot braking is more of a "sounds cool" kind of thing to do, but in practice, the results just aren't there (on the track). It's not BAD, but it's not better, and it's generally harder to get comfortable with and is easier to screw up. Once you've gotten comfortable with being very sensitive with your gas pedal getting on the gas, it's not hard to re-use that sensitivity getting off the gas.
I know a few professional drivers that like to do it, and I know about 5 times as many that don't like to do it. It's just personal preference. Personally, I'd recommend not. There are other things you could be learning and concentrating on that would make you go faster .
Quote:
Originally Posted by tyler_sti
One thing I was going to add is that. If one were to left foot brake in lets say a nice long 90-100mph right sweeper like big willow. You're entering the turn at either full or half throttle, at this point if you need to scrub off speed and release off the throttle you might initiate some over steer because the cars is already loaded on its left side at a high rate of speed. It dosen't always happen especially if you have good suspension, but I've found letting off in mid turn can be very dangerous especially without enough down force on the rear. I like to left foot brake because no only does it keep me in boost for the exit, but the weight transfer isn't as severe. IMO
First, even in a stock STI, turn 8 is a 120mph+ corner. If you're lifting or left foot braking at 90-100mph...don't. You should be flat through 8 if you're comfortable doing it. Aim for the inside of 8 and keep the pedal flat, as you get to the end of 8 release your steering and let the car gently glide out to about 1 car width from the outside of the track, do your braking in a straight line for 9, and get back on the gas.
With coilovers and any sort of good tires and/or aero, turn 8 quickly becomes a turn that is more about ***** than car capability.
But as for the left foot braking:
There is no difference in load and/or oversteer characteristics between left foot braking and gently reducing throttle. I'm not telling you to LIFT completely, simply if you're at 100% throttle, back off to 90%. This is exactly the same thing as remaining at 100% throttle and applying 5-10% brakes, but it requires only one foot. If you're getting oversteer lifting in sweepers, you're lifting too much. You could lift less, go faster, and keep things neutral, if that makes sense.
If it's easier for you to control the deceleration with left foot braking, go for it. It's not a bad thing. In regards to the "staying in boost" part of it, you shouldn't be lifting to the point that you fall out of boost anyway. Again, if your lift is that severe, that's why you're getting oversteer. 100% throttle -> 90% or 80% isn't going to drop you out of boost, and you're not going to be waiting for the turbo on the corner exit. The only way that would happen is if you lift completely.
Some of the terms you're using are concerning though:
Quote:
Originally Posted by tyler_sti
You're entering the turn at either full or half throttle
That's a HUGE difference. Which is it? If you're thinking of the gas pedal in increments of "OFF, HALF, and FULL" you'll benefit greatly by changing how you think about the gas pedal. There is a significant difference between even 90% and 100% throttle when you're at the limit, backing off to 50% throttle is like braking in terms of load transfer.
Quote:
Originally Posted by tyler_sti
I've found letting off in mid turn can be very dangerous
Again, letting off or lifting should mean 100% -> 90%, or 70% -> 50%. If you're thinking of letting off as removing your foot from the gas pedal, yes, that is EXTREMELY dangerous.
The problem with Subarus is people can get away with that kind of stuff and develop extremely bad habits. People lift or even brake mid turn, and many times, nothing bad happens. They then start to think that it's OK, and all this crap about driving smoothly and making subtle inputs doesn't apply to them. Then they drive a car that isn't nearly as forgiving (just about anything else besides an Evo or GTR) and have insane oversteer problems and go spinning off the track.
At the absolute LIMIT, a Subaru doesn't behave much differently than those "other" cars that are considerably more sensitive to load transfer and throttle input. However, until you get within about 5% of that limit, it's almost like the rules of driving don't even apply to an STI (they just understeer). In a normal car, these rules start to apply when you get within about 40% of the limit.
__________________
Ben Fried
RealityDesign
- 2008 Silver BMW 135i
- 2010 Team RD #027 Lotus 2-Eleven Race Car
________________________________________
Quote:
Originally Posted by Chris05STi
It was like your were in my head! Very good info, makes sense. We should have a Forza 3 meeting online for this!
Indeed. It's actually fun to mess with in Forza. One of the biggest things you can improve in that game is not mashing the joystick all the way to one side. The same concept applies in that game, if you push the joystick all the way to one side (full steering lock) you're asking your tires to turn more than they need to and causing understeer.
Quote:
Originally Posted by severe
well yeah my initial braking is really hard, i found this to help my times sometimes i get a single chirp from the abs kickin in also. i havent been to the track yet but my seat time is mainly in autox and im pretty much learning.
i generally slam them hard right before the turn, but reading your post i realize what i never do is release them smoothly. i just drop the brake pedal and then get my foot on the gas. i dont slam the gas i have a pretty good feel for the throttle and how the car reacts to minute adjustments mid turn.
based on what you wrote though it seems like i should take a split second longer in my brake release. i dont know how practical it will be since our autox setups are generally really tight and technical but its worthwhile to try and see if it'll help my times.
right now i can rotate the car a tiny bit with just throttle if i have the dif set to open, and it has some very slight understeer if i'm accelerating through the turn 1 notch up.
btw this has been on my mind, im generally screeching my tires around the entire course. i keep wondering if this is slowing me down or not. its right at the threshold usually i.e. if i remove a very small amount of steering input the screech goes away. i noticed most other guys aren't so aggresive though (though most of them also have rwd)
Two things here. First, this obviously matters a lot more at the track than at an auto cross, but the concept can still be applied. No matter what corner you're talking, a little trail braking will benefit your Subaru. It's just going to be an even quicker brake release in auto x because you brake considerably less and you're not going fast enough to be able to really get on the pedal hard without the ABS coming on.
As for tire screech, try not to rely on that. It's more of a crutch than anything. Really good r-compounds and any slick are completely silent. You don't hear any noise at all until you're backwards. The same goes with lockup / ABS, they don't chirp, you're just see silent tire smoke in your rear view (or in front of you in an open wheel car ).
The key is to feel that understeer coming on BEFORE the tires have to tell you about it. First, because if you correct it really early or avoid it altogether, you'll go much faster. The second reason is obviously as you get better tires you'll stop getting that audible warning. Now, with street tires and street suspension, you still have plenty of time to correct if you wait too long because everything is somewhat in slow motion. If you go to a stiffer, lighter car with stickier tires, everything happens much faster.
Quote:
Originally Posted by santacruz02
Ben, I'd assume the size or width of the front tires makes a difference as well. Like possibly understeer was cause from not having enough tire to pavement?
This actually makes no difference, unless you're suggesting running a DIFFERENT size tire in the front versus the rear. Whether you have 225's on all four corners or 315's you're still going to have identical understeer characteristics basically. The only difference is you'll get it at a slightly higher speed, but when the grip is still going to give up at the same point in the same fashion.
When you see cars with wider tires in the back than the front, they do this to artificially reduce front grip to compensate for oversteer problems. This is particularly noticeable in a Porsche.
You can actually mess with this in the opposite direction with a Subaru and it's kind of fun. Like running 245's in the front and 225's in the back, assuming you can find a tire with the same overall diameter as to not slowly destroy your center diff. Another way to toy with this is to run new tires on the front and used tires on the rear. I used to do this quite a bit, but just know that if you trail brake now, you'll DEFINITELY get oversteer.
Also, please keep in mind when I'm talking about new and used tires I'm talking about race tires, so the difference at most is 2/32's tire depth. If you put new street tires and almost bald street tires you'd probably have a 5/32's difference which isn't so great for your center diff.
Last but not least, and the easiest thing to adjust, is your tire pressures. Running more pressure in the rear than the front will also help make the car more neutral, or more oversteer prone after aggressive trail braking.
Obviously you can adjust suspension settings, swaybar settings, etc, but I like to go to them last for the fine tuning. I'll first start out with what makes the biggest difference (tires), then move on to aero (adjust rear downforce), and then move on to the suspension when the car is close to my liking.
A lot of people ask me why I run a considerably bigger front splitter than rear wing. Well, going back to our most basic load transfer example, the bigger splitter makes 400-500 pounds of downforce (front grip) versus the 300-350 that the rear wing makes (rear grip). The net result is more front grip than rear, which in a perfectly neutral car would cause oversteer, but in a Subaru just makes it more neutral.
Next time you see a Subaru at the track with a 10-foot wide wing raised to roof level and a little v-limited lip spoiler, you'll probably laugh now that you understand what he's actually done to his car.
Quote:
Originally Posted by thundercamel
I wonder this also. I use the tire squeal to know to not push it any harder, and keep it squealing through the turn (on a track). I had just a little squeal the first time, but I've been pushing it louder the last 2 times.
The squeal is your car not wanting to turn, and you either giving it more gas or more steering input. Now, depending on the tires, this squeal could be AFTER it's already understeering pretty badly, or when it's just starting. This is why I tell people not to really use the noise as their indicator.
Now, assuming this noise is the start of understeer for you, hearing the noise isn't terrible, but you could actually go faster if you got the car to rotate more initially before getting to power. The squeal would go away, you'd be on the gas sooner, and you'd have a higher exit speed. Depending on the corner, this may be almost impossible, especially in auto x since it's all understeery, slow, tight corners. Still, brake a little later and get some good trail braking in and you may find that you can still rotate the car before the apex even in those little 40mph corners that seem impossible to get through without plowing.
Quote:
Originally Posted by GotSTI?
I have had 8 hours of track time. 4 hours of class time. All of this was at Watkins Glen. Since I was new to it I was a novice. Still I was one of the fastest cars on the track rarely getting passed my first trip there and never getting passed my second trip there. Needless to say, I started getting Mario Andretti complex... thinking I was better than I was.
When I was at the track I heard people talking about late braking and I kept saying to myself I know these Brembos can handle me doing that. My first instructor had me do a lot of early braking whereas the second one did not. That's where I started to get into some trouble. I saw a lot of the RWD cars braking realllly early. Which made me want to brake realllly late. Quite honestly, this practice had me focusing so hard on timing the braking I wasn't thinking about my shifting and corner entry well. So, I hit the grass and got high up the curbing a couple times. This cost me a few extra track sessions before my instructor let me drive solo.
I learned to practice shifting smoothly on the straights so it would be better for the turns. It was too tempting to smash through gears on the straight away when you'd see a Z06 or something high powered in front of you. When in actuality being smooth and hitting the turn right made a bigger difference in catching those typ of cars.
Now I didn't try trail breaking but found that I could turn in later then other cars. I found that tactic built a lot of confidence / straighter lines through the turns. A LOT less worry about going off track too! I came out most turns a lot faster with this tactic. It was my second instructors advice that seemed to make a huge difference with this. I wonder if you could write your thoughts about this?
Also, I am wondering what is the ideal RPM going into turns for our cars. I found that most of the time I was in 4th and 5th at Watkins Glen (4th for turns). The only time I hit third was with slower cars in front of me. However, that generated a ton of power... or was it that I was just able to get on it earlier into the turns? It was very apparent as I got the point by a lot when this happened.
Lastly, how does heel toe work into this? I'm sure that's a whole other topic but I'd like your explanation on it as I can actually understand you!
Thanks Ben!
What you're describing is late apexing. It's always safer, and generally recommended when you're learning a track. The worst that happens is you go a little slower overall through a corner if you apex way too late. Then when you consider the worst thing that happens when you early apex is you run straight off the track...late apexing is the way to go. Generally speaking, the true apex of a corner is not the same thing as the geometric apex. Most corners require a slightly later apex than the "middle" if that makes sense.
The concept is most often referred to as "slow in, fast out." In other words, you brake a little bit more, you turn in a little bit later, but then you can get on the power really hard on the way out because you got most of your turning done in the first half of the corner. As you get more comfortable with trail braking, you can take that "slow in, fast out" concept and turn it in to "fast in, fast out" but it takes a lot of practice.
Most people, if not specifically told otherwise, will instinctively go "fast in, slow out" because they enter a corner too fast, understeer, scrub speed in the corner, and then get on the gas late at the exit. If you compare your "slow in, fast out" approach with their "fast in, slow out" you'll always be faster, and that's what you were seeing at the track.
Once you are 100% comfortable with the track (you know the line PERFECTLy) and you are 100% comfortable with your car and your driving, you can begin to try some trail braking. Essentially, this lets you carry more speed in to the corner while also reducing understeer. Yes, you can actually go faster and turn more. Thus the "fast in, fast out" principle.
On to RPM range for entering corners. I'd say 4000-5000 RPM. This gives you enough revs to let the gear wind out and not have to shift in a corner (bad!). On the flip side, I'd recommend shifting around 6500. There is no need to wind it all the way out to 7200 unless you're on a track where the end of a straight is just perfectly at 7200 and it would be slower to upshift and immediately downshift. Otherwise, you're being nicer to your motor and actually staying in a better power band (on most turbos). For example, on the engine I'm building I'll be shifting around 7000-7500 even though it's good for 8000-8500. There is just no reason to tempt fate or excessively stress components like that for little to no gain.
Finally, heal toe. Your heal-toe is done during phase 2 of braking. Phase 1 would be your primary stopping right at the beginning. Phase 2 is the rest of the stopping you need to do to make the corner, as well as your downshifting. Phase 3 is your brake release.
The reason for heal toe is that during phase 2 your right foot is on the brake, but you also need to hit the gas to blip the throttle when downshifting (for a rev-matched, smooth shift). There are two methods for heal toe, one is actual heal-toe (which I prefer, but most people don't) where you rotate your foot in such a way that your toes are on the brake and your heal hits the gas pedal. The more common way is to toe-toe, where you roll your foot across the pedals so the left side of your foot and your big toe is on the brake, and the right side of your foot hits the gas. This is easier for people with big feet or when pedals are tightly spaced together. For whatever reason, even with my size 12 shoes and fairly narrow pedals, I still prefer to heal toe as I feel it gives me more control over my braking.
Quote:
Originally Posted by TorstenW
Yeah, you're buddy in the Exige that just outbraked you on the inside and is about to claim position, lol.......
ps; Very nice write-up, btw
.
That quote is how to get comfortable with trail braking. When you start applying it in a race setting, you're braking later than that exige, entering the corner faster, and then getting on the power at almost the same time. The net result is usually a 5mph faster entry speed with a 10mph faster exit speed on say an 80mph corner.
That exige that late braked on the inside is off-line and is either going to have to forfeit his position, run in to me, or I'll let him in and watch him overshoot the corner as I pass him again on the exit (most common).
__________________
Ben Fried
RealityDesign
- 2008 Silver BMW 135i
- 2010 Team RD #027 Lotus 2-Eleven Race Car
Quote:
Originally Posted by subyalex
AMAZING post, I can't thank you enough or this insight Ben.
Now, if you could, maybe expand on how left foot braking may be able to assist with keeping the car neutral on long sweepers etc?
I learned alot fro this post, and made me realize how much I have to learn.
Some drivers left foot brake, most don't. It's more common in Rally, but you'd be surprised to find that most track drivers don't bother.
When you think about it, what is left foot braking doing? Decelerating mid corner. What would lifting off the gas slightly (20%) in a high speed sweeper be doing? Decelerating mid corner. What's the difference? If done properly, none, but you're not using two feet, and you're not heating up your brakes (not really a concern, but still a valid point).
Left foot braking is more of a "sounds cool" kind of thing to do, but in practice, the results just aren't there (on the track). It's not BAD, but it's not better, and it's generally harder to get comfortable with and is easier to screw up. Once you've gotten comfortable with being very sensitive with your gas pedal getting on the gas, it's not hard to re-use that sensitivity getting off the gas.
I know a few professional drivers that like to do it, and I know about 5 times as many that don't like to do it. It's just personal preference. Personally, I'd recommend not. There are other things you could be learning and concentrating on that would make you go faster .
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Last edited by sdaidoji; 01-26-2011 at 07:10 PM.
01-26-2011
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Rep Power: 787 Re: The Real Truth About Understeer - by Ben in Subaru forums
prolly interesting but too much reading. just get good tires and call it a day.
01-26-2011
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good reading nonetheless depending on how serious one is about the handling of the car and how to compensate it by driving style
- this the reason it goes to the racing forums 
04-29-2011
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Re: The Real Truth About Understeer - by Ben in Subaru forums
I read about a quarter of the way before I realized I don't pay this much attention to what I'm doing when I'm driving, I drive a Civic, and I don't take turns very fast anyways.
Seemed like a very good read though!
Seemed like a very good read though!
04-29-2011
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I don't either. After learning the concepts and fighting some of the counter-intuitive stuff, I just do it naturally, like turning the wheel the opposite way most would
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nope, that is one of the understeer recovery methods - turn the wheel to the outside, so it will have a chance to recover grip.
Technically, you unwind the wheel a little, not turn the opposite direction of the corner. When the car goes straight, most tend to turn the wheel even more, but that is wrong. it will make the tire slip angle increase even more - need to reduce tire slip. ^ It's up there
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Rep Power: 338 Re: The Real Truth About Understeer - by Ben in Subaru forums
Subarus are known to understeer like piggies - sqeeee, squeeeee, squeee!
I wouldn't post here if the basics are not applicable
I wouldn't post here if the basics are not applicable
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