I'm experiencing major vibs at speeds of 60mph & up. I've replace all u-joints and have tried 2 driveshafts...1 steel & stock 1LE aluminum. It's still there. Pinion bearing feels tight to. The vib feels like a bad u-joint but obviously isn't. An obvious question would be tire balancing, but the vibs are way to harsh! Any ideas, suggestions, or similar experiences?

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'91 Z28 1LE; 355, Sportsman II heads, Edelbrock TPI w/ 58mm TB, Tremec TKO 5-speed, 3.73's & much, much more

 

Is the vibration strickly related to vehicle speed? In other words, if you're cruising at 60 mph and shift down to a lower gear, does the vibration change?

If not, then start with the wheels/tires. I don't know why you think "the vibs are way too harsh" for tires - out of round, out of balance or slipped belt tires, or bent rims, will shake a car as much as anything.

If the vibration does change when you shift down, then you've got a problem related to the engine and/or transmission and/or clutch/flywheel. I assume you did the tranny swap yourself - are you sure you got all the right parts?

It is also possible you have a rear end problem, like a sticking brake caliper, bad pinion flange, bent axle, or something like that.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, TBD heads ported & polished, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

[This message has been edited by five7kid (edited March 15, 2001).]

 

I'm going to check the tires. The trans was professionally installed. That and the engine have been ruled out, it's definitely speed related, it doesn't vibrate at any other time. I know what you mean by a sticking caliper but that's ruled out to, car was just state inspected plus only has 15,000 original miles. It's a mystery!

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'91 Z28 1LE; 355, Sportsman II heads, Edelbrock TPI w/ 58mm TB, Tremec TKO 5-speed, 3.73's & much, much more

[This message has been edited by Ed1LE (edited March 14, 2001).]

 

My car had vibration like that when I bought it and it was so bad I could've sworn it was something to do with the driveshaft but it turned out to be the tires, so definitely get them balanced by a good shop just to rule that out.