I have a 97 Z28 A4. A few years ago I had 3.42 gears installed...what a difference. Well, the car runs well and I hear no noise coming from the rear end when crusing around town and even when accelerating hard. The problem occurs, however, when I SMASH the accelerator pedal to the floor and the car kicks back and downshifts....I head an extremely lound CLUNK from the rearend area. Someone told me it might be the U-joint that went bad. I do not hear any gear whine or anything like that...and the car is fine when driving around town ordinarily. When I changed my gears to 3.42, I noticed alot of vibration from the driveshaft above 85MPH. Someone told me that if I didnt fix it, the vibration would eventually damage the U-joint. What do you all think ? Also..if it is the U-joint, how much money will it be to replace it and all....including labor. THanks for the help

MiamiHeat
Miami

 

Probably just the tranny mount. A common problem. Under torque the tail of the tranny will come up and band the floor. Pretty cheap to fix.

 

 

Again, most likely you need a new tranny mount, most people replace their stock one with a 1LE mount. They are actually the only ones available now when you order one from a dealer. Not hard to replace and they are only around $25. I would also recomend replacing your stock steel "vibeshaft" with a LS1 aluminum ds, it will eliminate a lot of your high speed vibrations. They are around $220.00 new or you can find one in the for sale section here for around $150.00.

 

I'm not sure what you described is a u-joint problem but an easy way to check it out is get under it and grab the driveshaft and twist it back and forth to see if there is any play in the u-joints. You will probably need to jack up the rear of the car, chock the front wheels, put the car in nuetral and leave the e-brake off. You are only trying to check the u-joints so gentle twisting back and forth should tell you if anything is getting loose (should not be any detectable play in u-joints). A slight amount of play in the rear end is normal don't confuse that play and noise (from the Pinion to Ring Gear interface) with the u-joints. While you're there you can try pushing up and down on the pinion shaft by the back u-joint, play here is usually caused by a failing pinion shaft bearing (since you had the gears done it's posible that it either wasn't preloaded correctly or has gone bad).
If the u-joints are bad, simply remove the u-clamps at the pinion shaft and slide it out of the transmision. Many automotive parts/machine shops will sell and press in the joints for you. Call around for price on parts and labor, I think $30-60 for joints ("spicer") and $10-20 for labor each, they can do it while you wait.

Good luck

 

i'm going with tranny mount too

 

Chalk another vote up for the tranny mount.

 

Thanks for all the replies...you are all very helpfull. Where is the best place to order a tranny mount ?


Norm

 

i know thunder racing has them, that's where i got mine

 

Get under the car and look at it. It might simply just need to be tightened. That's all I had to do.