Are there any problems that will emulate the pulsating stops of a warped rotor? I had my pads replaced about three weeks ago, and the rotors looked good, so I declined to have them turned. Ever since there'* been a noticeable grab and release at slow speeds (like crawling up to the line at a stop light) and a vibration at high speeds. I suspected the rotors, and went back up to my friendly neighborhood mechanic to have them double check their work and measure the runout on each of the rotors. I also made sure to brake a little hard on the way there so as to heat up the rotors, hopefully making any warpage more pronounced. Measured runout on each rotor: 0.003", right at spec.

Any other ideas?

-b

Did they service the caliper pins?

I have no idea what those are -- the service included "cleaning and lubrication of the brake assembly," so read into that what you will.

-b

The grab and release at slow speed you describe is typical of a drum that is out of round. Of course this will contribute to vibration at higher speeds too while braking, does the steering wheel shake or does it feel like the whole car is whagging around a bit?

As for the rotors, many will say that the rotor should be shaved a couple of thousands just to ensure any previous pad material is removed and just to true them up perfectly. More worrisome may be the process of 'bedding' your pads - some pad material will transfer to the rotor surface and it may have done so in an uneven manner. GM recommends resurfacing the rotors every time the pads are replaced - in this case a surface grinder is preferred over a lathe when it'* only a question of prepping the surface.

Cheers,

Make sure the wheels are properly torqued, too tight or too loose is bad for our brakes.
The surging may be from weak brake lines that 'swell' up when the brakes applied as well?

Im getting the same condition. The front rotors were $65 each, and only have 6k on them. I inspected them yesterday and no signs of warpage by feeling them. Also, my steering wheel doesnt shake or pull, but the car shakes like a SOB. I think it has the origional drums at 92k, so they have to be it, right?

Jay

Some people say you feel runout at 0.001", though someone else mentioned the factory tolerance is 0.003". Either way, it'* not something you're going to feel with your hands.

It could well be your drums, they usually have sufficient metal to allow for them being turned so it might be a good thing to at least attempt. If you know the place well where you're going to have it done, I go to the dealer because I know them well and they only charge $12 Cdn each, them ask to make sure they only remove the minimum amount to true them up.

In your case Jay, if you're not feeling it in the steering wheel then it could well be the drums.

Cheers,

Word.

I work in a machine shop, so i can sense surface imperfections pretty well. Im just saying, I could not feel anything too bad. I am going to steal a run out gauge to use over the weekend.

I spoke to my parts guy. He said if after I test the rotors and they come up bad, he will warranty them 100%. Hes the best! He suggested applying the ebrake and seeing if it pulses, guess what im doing at lunch.... New drums are only $25. Sweet!

Jay

Blob of grease on a rotor or brake drum, perhaps?

yummy!