Warped Rotors?

[phewop118]

I had all four brake rotors and pads replaced about a year ago. Since then, I've driven nearly 25,000 miles and now the brakes are starting to feel bad again. When I apply light the brake lightly at anything above 30 mph, the steering wheel shakes back and forth and the brakes pulsate. I can also hear a sound from the front, drivers-side brake that sounds like something rubbing with each pulse. As I slow down, the pulsing decreases in frequency, and the rubbing sound decreases to match that. Even at 5 mph, if I press the brake lightly, i get this rubbing sound, but the duration of the rubbing lasts longer. The sound is almost like the sound of something being pulled on a carpet - a soft sound, not metal on metal.

I'm thinking my front rotors are warped. Anyone think I can simply have them resurfaced or turned? I really don't wanna put a lot of $$ into them, seeing that I have a few other repairs that I would prefer to do (a/c is important with dark leather in the summer) and they brakes are only a year old. What would be a reasonable rate to have 2 rotors resurfaced?

[maxwedge]

About 10-12 each here in upstate NY( off car). Make sure the slides are free, the mounting surfaces on the hub are rust free also.

[Rolm]

There are 2 reasons why brakes pulse, 1-you drive like a pussy and there is rust forming, fix for this is for you to find an open road crank the speed to abought 60 mi an hour and put the boots to the brakes do this three time and this should clean off most of the rust and that should be it. 2) If you installed cheap after market junk rotors they will warp after 10K to 20K miles. Note after market stuff is good most is not. Other advise "do not waste your money having the rotors turned if you do they will warp again.

[phewop118]

I do mostly highway miles. Very little city / stop&go driving, so I don't use the brakes much. Maybe 1 or 2 hard brakes in the last 25,000 miles. However, when I do brake for a light, it isn't light braking. Also, they are not aftermarket rotors - I got them at the dealer and they are supposed to be GM oem brakes. Perhaps I should just go with NAPA rotors.

[RUIntrigue'd]

Another thing that will cause rotors to warp is uneven tightening of the wheel lug nuts. They should be torqued in a cross-pattern to 65 ft-lbs.

[kmohr3]

I agree with RUIntrigued, but the correct torque spec is 100 ft lbs or 140 nm

[RUIntrigue'd]

I stand corrected on the torque spec......

[phewop118]

It is quite strange. The other day, the brakes were fine. Not a vibration or shake while braking. Then today, they are worse than ever, so that actually stopping the vehicle involves a jerky motion of quick stopping, slow stopping... It's as if I were pumping the pedal every second. It seems to be the front drivers side rotor - when i look at it, there are visible streaks on it from braking and they are 'bumpy'.

[LittleHoov]

You might go ahead and have the front ones turned just to help troubleshoot. I can almost guarantee they will warp again though.

If you have the stock rotors, theyre undersized to begin with, and then if youre taking material off of them, it will to some degree weaken their heat dissapating abilities. So more than likely youll be replacing them again soon. But turning them is a good temporary fix, and will at least make them straight for a while, long enough to see if thats whats causing the sound or not. Ive never heard of warped rotors causing a sound, but it sounds to me like yours are.

I would pull the pads off and see what they look like, if they are worn unevenly, it could mean your caliper is hanging, which COULD cause a sound from the fact that your pads are getting far too hot. Pads will sometimes make a creak or groaning sound simply because they get hot under normal use. If yours are hanging, theyre hot all the time, and whenever you touch the brakes you get that sound.

Just a couple theories/things to think about and try.