MAN! I can't keep my ride from shakin at speeds above 60MPH. I've had the front-end aligned, tires re-balanced, driveshaft balanced, new U-Joints, and it still has the shakes. I have 245ZR50's up front, and 255ZR50's in the rear on stock 16" rims. I've heard of the drive-saft being the prob, but after getting it balanced, it ain't helped a bit! I wonder if the Falken radials are the problem, I heard (after I bought 'em!) that they were cheap and characteristic of wearing funny, but I haven't had any problem with the treadwear, and the car shook before when I was using Pirellis, Yokahomas, and Bridgestones. In fact, I don't think the car ever ran smooth above 60 since I bought in new back in '89! Any help would be GREATY appreciated, fellow Camaro/Firebird enthusiasts!

 

Worn or loose suspension parts, like the "Idler Arm", usually hard to diagnose until it starts "feathering" your tires...

Noone added any "Fix-A-Flat" to your tires did they, My cousin did that one..it shook bad at highway speeds.

 

Maybe you've got a bent rim or something?

 

Well, when I had it aligned a few months back, I asked about the idler arm (it was replaced at 75K due to wear) and they told me it didn't need to be replaced but they would replace it if I REALLY wanted them to, so I left it as it was. I wondered about the bent rim thing myself, but wouldn't they have noticed that when they mounted and balanced the itres the last three times? I'd sure as heck hope so, but anything's possible these days. When I replace them with the 10-spoke SS wheels that'll eliminate that as being a possibility and who knows, maybe that'll fix the whole darned thing! Thanks for the info, dudes.

 

The steel driveshafts on these cars are known for higher speed vibration, even when balanced by a shop. That's why GM issued a TSB for this concern: replace with an aluminum driveshaft. It worked for me, and several others on this and many other boards. It's at least worth a shot. If it doesn't work, demand is high enough to resell it at your purchase price. I bought a factory aluminum driveshaft from a 6 speed LS1 car for $100- they swap right in.

 

How are the engine and tranny mounts?