Rep Power: 289

ok I've changed the rotors and pads on my girl's 92 corolla, had my man at the shop do my pads and rotors, and my father in law did my mother in laws pads and rotors. all 3 cars have a pulse in the brake pedal at no particular interval. feels like a rotational pulse if you feel it. I've checked all 3 cars' pads rotors, bolts and pistons in the calipers and nothing. 2 of the cars have abs and I know that is not the problem. no kinked lines. all 3 cars have fresh fluid. I'm thinking though it might be they weren't bled, but My guy at the shop said he bled mine.....could that be the problem? would air in the lines cause a mild pulse at random braking (not every time you brake)?

 
Rep Power: 812

well with air bubbles the brakes prolly wouldn't work.

 
Rep Power: 308

My last 2 Corollas had problems with the rear drums getting out of round. A simple test is, at moderate speed hold the button in on the parking brake and then pull it up with medium pressure(make sure it is clear of traffic of course) If it is caused by the drums you will get a similar pulsation as you explained. My 91 Prizm and 00 Corolla both had this same problem.

 
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^ and if they are fine you then you should whip the steering wheel and do a 360

 
Rep Power: 331

did you do any type of break-in procedure? you cant stomp on brand new pads and rotors without breaking them in properly.

 
Rep Power: 289

yeah all were broke in to 500 miles at least with steady braking.

wouldn't that be odd though on 3 cars of dif makes all at the same time?

BTW the only way to measure "accurately" would be to measure run out on the drum right? aside from the fact I really don't feel comfortable doing that test hehe

 
Rep Power: 0

When you do not bleed the brakes or get air in them they will fade especially when you need them the most. Usually when you have a jerkyness to the car its a warped rotor or drum. Typically if you ask a mechanic they will tell you to turn all rotors/drums on your car every time you change the pads/shoes. I would say pull your rotors have them turned and or at least have them check the rotors/drums for true.

EDit btw if you use hard ceramic pads on soft oem rotors and you ever get on the brakes with abs you will eat the rotors.

 
Rep Power: 397

I take it they were checked for warping.

 
Rep Power: 289

yup check.


I also did the parking brake thing and felt nothing, cept of course the minimal amount of stopping power the drums offer.

 
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^^^^ If that didnt work, then like TheSmuggler said, it could very well be warping of the front disks.

 
Rep Power: 289

you would feel the warping every time you braked.....but I don't....and I guess lemme try to clairfy the feeling a little more:
when you step on the brake its not so much a feeling in the pedal as it is in the entire car as well, it's kind of doing small very quick lurches as you're slowing down, the more decelerated you become the slower the longer thje interval between the lurches become, cuz my girl feels them even when shes is in the car with me. and it doesn't happen every time either, it's random so I can't pinpoint a speed at which it happens.

 
Rep Power: 0

^^ yea that is a sign of warping. You may want to pull the rotors and double check. What type of pads did you use and is it an oem rotor?

A real good test it to brake slow a a good speed and you should feel it and or when you get on them really hard. My girls brakes on her 6th gen are oem rotors(which i did not turn) and ceramic pads. They have chewed the oem rotors up bad enough to warp them and it does not always shake the whole car but they are still warped none the less. Brakes have changed alot since the whole asbestos free crap has come out they squeal horribly and fade easy. Its hard to find a good combo...but i say that the aftermarket rotor(slotted/crossdrilled) and hard ceramic pads(napa is by far the best I have tried) have been the best combo I have ever had. Not only do they not make any noise but I have got on my brakes and abs has come on enough times that I thought for sure my rotors where either going to heat score or warp and they have not yet done either. But like I say just pull the rotors and at least check them or have them checked by a different place that did the turning you might be suprised.

 
Rep Power: 289

warping is a constant feeling though isn't it? everytime you brake?

 
Rep Power: 397

Not necessarily

 
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how akward, i have the same symptoms on my '04 but i barely have 18,000 miles...........could the OEM pads and rotors get warped that early?!?!?!? i dont drive that hard either..

 
Rep Power: 328

.0005" of unparallisim in a rotor can cause a pulsation, the pulsation may or may not be a constant. I would recommend having the rotors machined on the car and make sure that the slides are clean and lubed

 
Rep Power: 289

I figure its not a problem or one that can turn into something larger....I mean cuz all 3 cars had brand new pads and rotors put on max mileage is about 3500 miles minimum is about 400 miles....just doesn't make sense to me....

 
Rep Power: 397

I told ya it was unloading in third!

 
Rep Power: 375

It sounds like your rotors are unbalanced. you can either get them turned at a shop or just wait for the pads to break into the wear pattern, just like the ones you replaced were. ive just learned about rotors being unbalanced and all the vibrations it causes; my right front oem rotor is warped and causing the car to shake at high speeds - the wheel, tire, and suspension are almost perfectly true.

 
Rep Power: 289

this is going to make me look like a fool but I dunno care cuz i'm learning everyday....but, I though tturning the rotors meant literally turning them a full 180* on the studs

 
Rep Power: 375

no biggie, resurfacing/ refacing/ turning rotors is all the same. basically a shop takes a flat grind to the surface of the rotor to even out warping and scoring on the actual braking surface making it like new.