I have an '82 vette. I recently replaced my rear rotors, pads, metal caliper lines, flex hoses and rear shocks. When I went to test drive it, the rear end has a noticeable wobble now. I was doing about 5-10mph and you could really feel the wobble. It wobbles when driving, not braking. I was rocking side to side in my seat. I took the wheels off and checked the parking brake to see if it's dragging on one side and it's not. I even checked to see that the rotors are seated flush with the spindle and the lug nuts are torqued correctly. This is frustrating! By the way, the rotors are made in China. Could they somehow cause the wobble?

 

Doesnt sound related but I would have the tires balanced before I did anything else

Sounds like a bent rim to me

 

The rear spindle and rotor are a machined set from the factory.The rotor is machined after it is riveted to the spindle.The spindle face can be out as much as .010 or more and when you bolt up a rotor that is perfect you have a wobble.The factory decided that making both the spindle face and the rotor with 0 runout was not necessary.You can try indexing your rotor(rotating)but if your rotor is 0 it wont matter-I use shims for the stubborn ones or replace spindle.

 

Wobble that you feel in the seat is caused by tire tread squirm or wheel runout. Excessive rotor runout will cause pulsating brakes, but not necessarily at low speeds.
You need to check the runout at the wheel rim as you turn the wheel. The easiest way to check wheel runout is to jack the car up so the wheel can be turned by hand, then fix an indicator next to the rim so that you can see how much runout you're getting as you turn the wheel. If the wheel is not wobbling mroe than about 1/16 inch, that's not your problem.... it's the tires.
If it wobbles more than 1/16, then you have to decide if there's something keeping the rotor from seating against the hub, or if the wheel is bent.
Another strange thing about tire squirm is that often both rear tires have some amount of squirm, and as they rotate and change position relative to one another, the wobble you feel in the seat of your pants will increase and decrease as you drive. This is because when the tires are both squirming the same direction at the same time, the whole car goes with it. As you drive and go around some corners forcing the tires to travel different distances, they get out of phase causing the right tire to squirm left while the right squirms right, cancelling each other out resulting in no or little wobbling motion in the car.

 

What kind of shape are the trailing arm bushings in? I know it's probably not related, but that sounds a lot like how my 81 felt before we replaced them. When I got them out, there was virtually no rubber left. The car felt like what I would imagine driving a roadgrader would feel like.

 

The wobble wasn't there before I did my brakes. I might put my old rotors back on to see if the wobble goes away. If it does then I'll know it's the new rotors that's causing the wobble.

 

DOn't bother with the old rotors, your going to lose your setup when you take it apart. Jack it up and check for wheel runout first, if its not there, then pull the wheels and look further into rotor runout. You may just not have the rotor run all the way down on the hub on one wheel.

 

Speaking of rear end wobble, I'll be doing this ---> at Hooters in approx 60 minutes.

 

I found the problem. It was the right rear rotor not seating properly. I took the wheel off and put just the lug nuts on to tighten the rotor against the spindle. I turned the rotor and it wouldn't move. I knew the parking brake was already off so it couldn't be that. I then looked through the parking brake adjusting hole and noticed the rotor wasn't seating against the spindle. There was a noticeable gap. I took the rotor off and found that the rivets weren't drilled out completely so the rivet shafts weren't flush with the spindle face. The new rotors don't have the rivet holes so the shafts would hit the rotor mounting surface preventing proper seating. My old rotors have the rivet holes in them. Whoever drilled the rivets originally did a good job on the left side (no rivets at all) but left the shafts on the right side. I should've noticed the difference between the new and old rotors in the first place and prevented this headache. DOH!

 

Feels good dont it!
Good for you