What brakes are required for 19" rims?

[Jasdip]

Hey guys, i just wanted to know what brakes I should get before I put 19" rims on my car...First off, am i required to change them in the first place? Second, can you guys tell me what I should get..maybe a link to where I can get them too...I don't even know everything that is involved when speaking of new "brakes"...Thanks!

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[mneuls]

as far as I know, you don't need to change anything. I have heard that if you have your ride dropped, you get some rubbage with 19's

[chawski]

depending on how much you are willing to spend, AEM, Brembo, Wilwood, and Stoptech are some of the bigger names in brakes. Plan on spending a few bucks on these. Its a long shot, but you may be able to find a parts car with a 4x100 pattern and larger brakes and grab those. Whatever route you go, youre asking for trouble with 19s on stock brakes. Stay away from any wheel shop that tells you otherwise.

[Jasdip]

Originally Posted by chawski

depending on how much you are willing to spend, AEM, Brembo, Wilwood, and Stoptech are some of the bigger names in brakes. Plan on spending a few bucks on these. Its a long shot, but you may be able to find a parts car with a 4x100 pattern and larger brakes and grab those. Whatever route you go, youre asking for trouble with 19s on stock brakes. Stay away from any wheel shop that tells you otherwise.

What kind of trouble can I come across? And would I need a set for the front and back or only the front?

[FALKEN]

im sitting on 19s with a drop, no rubbing issues, and running the stock rotors with 40K miles on the same pads.

[Jasdip]

Originally Posted by FALKEN

im sitting on 19s with a drop, no rubbing issues, and running the stock rotors with 40K miles on the same pads.

Can you send me pics of your car? Also, by putting 19s on the stock brakes, i won't damage the brakes or anythin else will I?

By the way, my car isn't dropped..but it has the aero kit...hopefully i dont have to drop it..

[yamahaSHO]

Without better brakes, your stopping distances WILL increase and the rotors WILL run hotter for a given stop. At a MINIMUM, I would get a set of better pads.

[mneuls]

what is the reasoning behind that? i know that it will be harder to brake and squeal the tires, (which is a good thing), but your car should weigh the same, or less, so why would your braking distance increase? that doesn't make any sense. the only factor that changes with bigger rims is usually wider tires, so they are more grippy, which should logically shorten your braking distance. sounds like a bunch of propaganda to get you to buy brakes and waste your money. also your brakes should have better airflow, so they would bee cooler than with stock tires and crappy steel rims.

[chawski]

the braking dist will increase bc the wheels are heavier and there is more rotational mass. like previously stated, your brakes will run hotter, which will cause fade, and increase stopping distance even more.
there are 2 main reasons for going with bigger brakes:

1) heat dissipation. if you use your stock brakes, there is very little surface area for the heat to spread. youve gata realize that stock civic rotors are about the size of a large bagel. brake fade will develop here because the rotors and pads overheat. they are designed to work at a certain temperature, and as you exceed that temperature, your braking performance quickly goes to hell. you are also more prone to rotor warping/cracking with the added heat/stress.

2) more bite. using a larger rotor/caliper will allow you to use a larger pad. as you increase the surface area, you increase the amount of friction, or stopping power, you have.

the only factor that changes with bigger rims is usually wider tires, so they are more grippy, which should logically shorten your braking distance. sounds like a bunch of propaganda to get you to buy brakes and waste your money.

wider tires create more drag. they will take more energy input to start rotating them and just as much more to stop them

[xcrxss]

I have 18s which yeah, are different 19s but I've never had a problem at all.

[yamahaSHO]

Originally Posted by mneuls

what is the reasoning behind that? i know that it will be harder to brake and squeal the tires, (which is a good thing), but your car should weigh the same, or less, so why would your braking distance increase? that doesn't make any sense.

No, that statement doesn't make any sense....

Originally Posted by mneuls

the only factor that changes with bigger rims is usually wider tires, so they are more grippy, which should logically shorten your braking distance. sounds like a bunch of propaganda to get you to buy brakes and waste your money. also your brakes should have better airflow, so they would bee cooler than with stock tires and crappy steel rims.

Ah.... You have MUCH to learn


Not only will 19's add more weight to the car, but they'll add weight in the absolute worst place. You'll have added rotational and unsprung weight. Extra rotational weight will be harder to get going and stopping (especially with such a big rim as your weight been moved outward to give it more leverage). Unsprung weight will also have ill effects in handling and could wear out a stock suspension quicker on bumpy roads. The suspension, believe it or not, was designed to handle the weight of the stock components. When you start increasing the weight, it now has to fight that weight in dampning and rebound.

You may not notice the ill-handling effects as you'll be going with a bigger, wider rim/tire that will have minimal roll, much more stiffness, and likely a larger contact patch.

Originally Posted by chawski

2) more bite. using a larger rotor/caliper will allow you to use a larger pad. as you increase the surface area, you increase the amount of friction, or stopping power, you have.

To add to that, it's not so much the larger pad that does more braking, it is the increased leverage from moving the caliper outward. In addition, a wider pad will be better than a taller pad as it uses the majority of its clamp load on the outer edge of the rotor.

You are very correct about removing heat. On my SHO, I have 13" x 1.1" rotoar up front with a 2-piston aluminum caliper. The big rotor not only has much more leverage, it is able to spread and shed more heat. The aluminum caliper is also better at removing heat so that the fluid doesn't boil. On top of that, I have brake cooling ducts putting fresh air into the center of the rotor to pump the air through the vanes.






This thread was just posted on the SHO Forum last week. If you ever wanted to know the ill effects (aside from the good things you probably already know), read some of the links on this page ---> http://www.rx8club.com/showthread.php?t=51865

Personally, I've held the 17" wheels from my SHO up to my Civic and I couldn't imagine wanting a bigger wheel than that on the little ass car.

[Zzyzx]

Originally Posted by chawski

1) heat dissipation. if you use your stock brakes, there is very little surface area for the heat to spread. youve gata realize that stock civic rotors are about the size of a large bagel. brake fade will develop here because the rotors and pads overheat. they are designed to work at a certain temperature, and as you exceed that temperature, your braking performance quickly goes to hell. you are also more prone to rotor warping/cracking with the added heat/stress.

2) more bite. using a larger rotor/caliper will allow you to use a larger pad. as you increase the surface area, you increase the amount of friction, or stopping power, you have.

#1 is more or less correct. #2 is incorrect given that friction is not subject to surface area. just Pressure and the coefficient of friction of the two items.


Regardless, unless this guy is using his car for competition or flying through mountain roads then the only problem he might run in to would be premature pad wear. No big deal.

Originally Posted by yamahaSHO

To add to that, it's not so much the larger pad that does more braking, it is the increased leverage from moving the caliper outward.

Common brake misquote. The only thing you'd have done by increasing leverage is change the "feel" of the brakes. As in you've increased the amount of torque the brakes can apply to the tires given the same pressure on the brake pedal. But since you haven't increased the amount of torque the tires can apply to the ground then your "stopping power" will have remained the same, as well as your stopping distances.

[chawski]

#2 is incorrect given that friction is not subject to surface area. just Pressure and the coefficient of friction of the two items.

good point, thanks for the correction. its been a minute or 2 since physics class

let me correct #2: Big brakes look sexy as hell. thats why you should get them.

[mneuls]

what I meant, is you can apply more pressure to the brake before the tires will break loose from the pavement, because the tire pad is larger.

where you guys are wrong, is that an alloy rim is heavier than the stock rim and tire. (not a steel rim, they are pretty damn heavy.)

A stock rim and tire weighs about 55 lbs
a 17 alloy rim and tire weighs about 45 lbs
and a 19" alloy rim and tire combo weighs a whopping 48 lbs, which is 7 lbs lighter than the stock combo.

you are cutting "unsprung weight" so you shouldn't need as much braking power.
(the purpose of the alloy rim is to cut weight to increase performance) if you are buying heave steel rims just to look good; don't, just save your money and buy some lightweight ones.
and your brakes don't need to be big, or drilled out, although I do agree they look sexy, but they are definitely not required.

[Zzyzx]

You are forgetting a little thing called Polar moment of Inertia...

Simple Formula to calculate that would be I = M*R^2

where:
I = Inertia
M= Mass
R= Radius (squared in this case)

So Take your 55# stock setup as A 15" wheel.

Given that you could estimate that its Inertia should be around 905078.835 N.

Compaire that to your 19" that weighs 48 LBS.... @ 1264609.576983 N.... Almost a 30% increase in Inertia.

Meaning given those two setups it takes almost 30% more energy to accelerate and decelerate the 19" wheel as compaired to the 15" wheel.


And Unsprung Vs Spring weight has nothing to do with accelerating or braking but rather in your suspensions performance (I.e. Handling).