UGOT8

I had a 3.73 Motive Performance gear installed in my A4 car..

During the install, the mechanic replaced all bearings and seals and put in new dope..

Immediately after the install, my car had gained a vibration.

This vibration is nearly un-noticable at low speeds, but the faster you go, the worse it gets. It also wines but the wine and the vibration are different speeds.

The vibration is a throbbing vibration.. getting substantially worse around 80mph, and busting a tailshaft housing in half at 120...

What the hell is up? I'm checking the axles. The wheels and tires are fine.. i've had them checked. When the tailshaft busted I had the driveshaft balanced and new yokes put on..

What most likely is causing this vibration? It drives me crazy... and I'm sure its not good for the rest of my car..

Could it be the setup? Maybe needs re-shimmed?

TIA,

Austin

UGOT8

somebody?

PHIL H

iTrader: (13)

still have a steel d.s.? If so thats prolly it..This forum has been full of tail-shaft busting talk lately..

UGOT8

I do have a steel driveshaft but I took it to Huntsville Driveshaft and had it checked.. and balanced.. and new yokes put on.

Why would it be the material of the driveshaft? I don't understand.

RevGTO

iTrader: (12)

Agree with Phil ... an aluminum ds cured this problem on my 94 LT1 car. It started at 90 and got progressively worse.

Slowhawk

iTrader: (12)

Could be a loose pinion nut..If the pinion loosens up it introduces play and vibrates worse as speed goes up.

robertbartsch

...wouldn't you get a vibration if the lash on the pinion gear is not set right? ...was the lash checked with a dial indicator?

Mike02Z

iTrader: (13)

I had a very similar problem with my 94Z. At 84 MPH and above I would get a vibration. Under acceleration it was fine but as soon as I let my foot off the gas above 84 it would sound like the car was going to come apart. I had the entire rear swapped out (a buddy was SURE this was the problem) and the problem persisted. I then had the wheels and tires balanced but still had the problem. Turned out it is was the drive shaft. I swapped my steel one out with a shaft from an LS1 car and the probelm went away.

UGOT8

You guys that had this problem.. and switched to aluminum driveshaft and it fixed the problem.. When did the vibration start for you?

Mine didn't start until immediately after I got my 3.73s installed. I just don't understand how it could be the steel driveshaft especially since I've had this driveshaft professionally balanced but.. I will try anything to fix this

Thanks

Mike02Z

iTrader: (13)

I only owned my 94Z for 18 months and it had the issue when I bought it. It had 88k when I bought it and 106k when I replaced the drive shift. I did not change gears while I owned it but I did change the entire rear at about 100K and it did not help until the ds was replaced.

XFiveLiter

You 3.73's are spinning the drive shaft about 25% faster at the same speed than your 2.73's were. Any problem you have w/the drive shaft will be compounded w/more gear.

I think it would be worth the effort to try a different ds.