Rep Power: 812

has anyone noticed on these cars the brakes have a mind of their own? i get the usual terrible performance the first drive of the day since i assume some rust has built up (even in 10% humidity with no rain and desert climate), and after maybe 5 braking cycles they stop grinding and work better. but even once they are warmed up, the stopping power varies quite a bit. i never know what to expect the next time i press the pedal. sometimes they stop great, other times i feel like i have to mash down the pedal to get anything to happen. it also seems to vary by day. for example driving around last night they felt amazing and stopped hard and fast. this morning it felt like some of the brakes took a vacation. the brakes were replaced about a year ago with new oem everything (new rotors and pads, new shoes and resurface drums) and the pedal travel is the same every time. fluid is new. physically i see nothing wrong with the system, just a variation in braking performance. it has good and bad days, just like the engine. i know there is prolly no explanation, but its interesting how there can be such a big difference in how the car drives from day to day, given roughly the same environmental conditions.

 
Rep Power: 188

Do you have OEM brake lines? I was reading somewhere that the temp plays a role in how much the brake lines give. For example after the car has been on for a while the brake fluid warms the brake line letting it stretch a little more when you push the pedal then when it is cold. Just a thought

 
Rep Power: 812

yeah all old oem 100k miles rubber lines. makes sense. i also know the brake booster performance gets affected by available vacuum. for example when the a/c compressor is on, it will affect how well the booster works. im curious what else would affect overall vacuum and i dont have a gauge or anything to test out different things. the manual wasnt much help. looks like stainless lines may be in the works.

 
Rep Power: 812

well i dont think its heat. its been close to 90F during the day and when i go out in the afternoon/evening the brakes are very good. seems to be a morning thing for the most part and i wonder if the barometric pressure changes from morning to evening is causing a lower vacuum or something. surprisingly the car loves hot days and esp right when the sun goes down when its still warm. i wonder if system voltage has any influence on the brakes? because normally when you press the brakes, the 60w draw is supposed to tell the ELD to bump voltage from 11.8 to 13.8 as you are stopping. my led brakes only draw 30w and the voltage stays at 11.8 even after i come to a stop (unless i switch to neutral). this prolly explains why my battery doesnt charge as much, but is there anything electrical that could explain the bad brake performance?

 
Rep Power: 256

hawk HPS problem solved.

 
Rep Power: 188

im going with hps pads and stainless lines. also ebc slotted rotors (purely for bling and the fact they are powdercoated)

not sure when im going to buy the parts tho

 
Rep Power: 812

i went out again this evening, same conditions, and i had to press the pedal as hard as i could to get decent stopping power. not sure whats going on with this car. and im talking 30-0 mph stops too nothing that extreme. i would go with the hps but heard they are louder, dustier, and eat the rotors faster.

 
Rep Power: 294

Tires play a big part in this too. More grip at higher temps/increased pressure vs. morning start up.

 
Rep Power: 367

still rocking stock rotors at 108k... stock rear drums all the way to shoes...

 
Rep Power: 210

I would look at the power brake booster. It sounds like at times you have full assist and at others almost none. Vacuum varies from lowest at wide open throttle to highest at deceleration with a closed throttle. Generally vacuum is pretty high under the conditions when you apply the brakes. There is usually a check valve in the booster that helps maintain the vacuum in the booster at the highest level, this is why you usually get one 'good' stop with the brakes after you shut off the engine. If there is a problem with the check valve or a leak the booster may not be maintaining enough vacuum to assist braking.

You could borrow a vacuum gauge but this will only tell you engine vacuum which varies. What you really want to know is booster vacuum and I don't know of a way to test that.

 
Rep Power: 812

i should check the manual, i know they have some troubleshooting steps but yeah thats exactly what it feels like. the pedal feels the same but the amount of "assist" is different each time. it feels like too much of a difference to just be from tires/heat. and it was fine in the winter. if the booster checks out, do you know what other devices would lower the available vacuum? so far a/c compressor is the only one i can think of and i almost never use it. i wont even begin to explain how terrible braking is with the a/c on. doesnt even feel like the same car anymore. the other thing is i dont think this car really has a vac system like older hondas did. so there are no lines that can be checked. altho, i did notice one of the larger vacuum hoses on the booster was brown and dry rotted compared to the others. i wonder if its worth replacing just to see.

 
Rep Power: 253

Think perhaps your slide pins could need grease?

Perhaps a blockage somewhere in a vaccum line? Pull it off and put finger on the end with the car running and turn the ac on see if it drops dramatically. I am sure you could measure vaccum at that point to see if it is within spec.

 
Rep Power: 352

my brakes are fantastic man...

but my sister's stock 03 ex suck like hell... ss lines, super great pads and good brake fluid make such a difference.

 
Rep Power: 235

Sounds like the booster or the valve in the booster hose is bad. You can hook a vacuum pump w/gauge to test. Use one of these (about $50): http://www.mityvac.com/pages/products_hvpk.asp

 
Rep Power: 812

well the hose is $20 and looks terrible, i think i will replace that and see what happens. im guessing with that kind of price, it has the valve inside already.

 
Rep Power: 210

Vacuum is created by the engine trying to pull air past the throttle plate. The cylinders act as air pumps and when the throttle is wide open there is less restriction and better air flow so the vacuum drops. When the throttle is closed the engine is trying to pull air past it and this causes the vacuum. You expect the least amount of vacuum under WOT acceleration and maximum vacuum under deceleration. Vacuum is also fairly high at idle since the throttle is closed but the engine is not turning as fast as it would be if it were decelerating or braking the car. Years ago some manufactures would use a vacuum gauge on the dash to indicate fuel economy. Different engines develope different amounts of vacuuum based on design. Generally, higher performance engines build less vacuum because they breath better.

Off the top of my head, the only thing I can think of that would cause a drop in vacuum would be a leak such as a cracked hose or intake manifold gasket. If the leak is bad enough you would hear a hissing sound. As I mentioned the level of vacuum changes so part of the function of the booster is to store it when it is at high levels.

You mention the hose to the booster and that could be the problem as well. If it is soft on the inside it could be collapsing which would prevent the vacuum from reaching the booster. You may be able to test the hose by removing it at the booster and checking for vacuum. As I said, at idle the vacuum should fairly high. If there is no blockage you should be able to either measure or feel the vacuum. Be aware that the engine may run poorly when the hose is off if it is open since it will allow air into the engine that is not going past the sensors.

 
Rep Power: 812

yeah let me try the hose and see what happens. im also not very happy with the play in the brake pedal but im thinking its always been like that. i have to push it down quite a bit before it stops and even when i start feeling the brakes, i have to press down hard on the pedal. granted im not stopping like grandma, but im close to maxing them out as i dont think i could press much harder if i needed to stop fast in an emergency. maybe i forgot how suck the brakes were but i remember them being better than this a long time ago. there are some times where im pressing down as much as i can and it feels like the brakes are easing off and i sometimes cant stop exactly where i was aiming for.

 
Rep Power: 235

correct

 
Rep Power: 812

i think something happened after i started squeezing certain parts of the hose. there might be some type of blockage in there. im headed to dealer to grab a new one and throw it on.

 
Rep Power: 812

well dealer wanted way too much so this will be thru majestic again when i think of other stuff to order. i took the car out for a city drive and really beat on the brakes, and it seems to have helped. i know the shoes take forever to wear in so maybe they are still not quite broken in. im gonna keep heating them and see what happens. usually this car shapes up when you give it a good beating lol. and im prolly expecting too much from a civic to begin with.

 
Rep Power: 235

Yeah, the dealers around here charge 30-40% over retail.