Brake / Steering Wheel Shake :(

[ILjXYZ]

I have a 1994 Pontiac Firebird (V6) and it has a nasty problem. While braking at freeway speeds (60mph+) my steering wheel shakes violently, which in turn makes the whole frontend feel like it's shaking. The car stays perfectly straight on the road, however. I'd almost say that this only occurs once the rotors are heated up (after braking a few times on the freeway) but I'm not quite certain. Sometimes I'll drive for 15 miles on the freeway without braking once and then have to brake and they will be smoother than usual (but certainly not smooth), but after braking a few times after that they turn horrible.

I've had the car for about 2 1/2 years now and it did not do this when I bought it. This is something that has been going on for some time (probably a year and a half) and I can not figure out why. In an effort to fix this problem I have done several things to my car. I have rotated the tires numerous times (they're back in their original rotation now), I have replaced the front and rear shocks, I've had the tires computer aligned, and I have new (as of a few months ago) high quality brake pads on the front. I've had my current rotors turned once and it seemed to fix the problem for a little while but alas it soon returned. The tires are all in good shape, high quality Futuras A-rated all the way around. One of my front tires has an inside patch on it but that doesn't seem to be the problem as the problem still occured even when I rotated it to the back.

I do have my suspicious about the brake rotors, however. I replaced them probably a good 2 years ago and, while I can't quite remember when this problem first started occuring, I think it was around the same time. The rotors are one of the cheapest that the auto parts store carries and I'm thinking they can't handle the heat of all the braking I've done. On the passenger-side rotor there is a ridge on the surface that isn't on the driver-side rotor. My brake pedal pulses at slower speeds which I attribute to this ridge, but could that also cause the shaking at higher speeds?

I've thought about replacing my rotors but I'm torn over what to replace them with. Are the cross-drilled and slotted rotors worth getting if all I do is drive around town and commute 60 miles a day on the freeway? Or, should I go with some high quality "flat" rotors instead? I wonder if that's even the problem. :/

Anyway, any help would be appreciated. Thanks.

-Charlie

[Philo]

I think you are correct in that you do have warped rotors. Pulsing on light brake application and shaking on heavy application are exactly the experience I have had. On occasion, you can have them turned to remove the warp, but because you already have used them for a couple of years, they may not be able to be turned enough - since they are shaking the whole car they are probably warped a lot. It is almost pot luck getting rotors if you get the factory equipment. I ordered a set from JCWhitney one time because I could not find a set that did not warp. They turned out to be the best rotors I ever had. And they came from China. The 'racing' types may be better - but get quality and ask about warping.

[burnM]

I agree with Philo, the problem is most likely the rotors. Unless you have some kind of balljoint/tie rod damage that wasn't detected during the alignment, or you have a caliper that is ceasing up.
Buy the best quality flat surface rotors that you can find. Then buy organic pads. The rotors will last for a long time that way, but you'll have to change your pads more often. It depends on the way that you drive.
If you don't mind changing your rotors every couple of years, go with a cheap set again. But I do think that changing them will solve your problem.

[ILjXYZ]

Thanks for the replys, guys. I appreciate the feedback. I think you both are right in saying that my rotors are most likely warped. Is there any way I can tell for sure that they're warped when I take them off? I think I'll try to replace them this weekend and let you guys know how it went, if possible. Thanks again,

-Charlie

[burnM]

You can pick up a dial indicator that hooks to the hub. It reads runnout with a needle that rides along the rotor as you spin it.
But the price of a good dial indicator can be as much as the rotors!

[tomminajar]

umm the steering wheel shouldn't shake when you brake if the rotors are bad- the Bpedal should plusate if rotor is warped = steering shake sounds like suspention problem

Take the brakes off and look at both sides in out board if one pad is worn more than the other caliper is hanging up - and if its warped the rotor may be 'blued' in certain spots due to uneven wear spots- but you would should be able to feel the bpedal pulse when braking from 60 mph or 15 mph when ever any brake psi is appied