Sorry this is long, but I'm at my wits end.

Ever since I have had 3.73 gears put in, I have gotten a vibration at 80+. Not an "this is unsafe" vibration, but one where you know it isn't good.

I figure it can be either:

1: Engine - NO - vibration not related to RPM, just to MPH

2: Tranny - NO - I took out the driveshaft and ran the tranny up to like 120 (losing a cup of fluid i the process) and it was as smooth as can be. It wasn't under load, though, if that affects it.

3: DS - I have a stock LS1 driveshaft, and had it balanced, and the guy said it was fine, he just added a .25 oz weight to it.

4: Yoke/rear end internals - Can these even cause a vibration?

5: Axles - I bent my old driveshaft at a race right before I got the 3.73's (misshifted going into turn 17 at Sebring and locked up the rear wheels), so could I have bent my axles and not known it?

6: Rotors - Doubt it, they are the BAER 2 piece.

7: Wheels - Had them balanced recently, but possible.

You would think it would be the DS because it is spinning faster but it was a reputable shop and tehy said it was fine.

So, How can I test these things? Just putting the rear up on jackstands and taking them off one by one sounds pretty dangerous, but I'm getting to that point.

 

ttt

 

Is this felt more thru the steering wheel, or more thru the seat?

check tires for condition. (scalloped, uneven wear, separation, and such) Rebalance wheels/tires. Also, check for loose/worn parts in drivetrain. (u-joints, pinion bearings, etc.)

 

i have the same problem for the last month i have had a bad vibration. but the weird thing is it only does it every now and again. it started off and on when i had to pull the tranny to put a seal in it. It is like i can get on it and it will do it. then i can stop and it will stop. then i can not get on it and it will do it then i get on it and it stops. it does it in every gear. i know it isn't ujoints bearings in the rear or in the tranny. the only thing that i can thing of is drive shaft out of balance. what else may i be over looking.

 

It's felt through the seat, not the steering wheel.

 

When they balanced the driveshaft, would they have known if the u joints were bad and causing a vibration?

 

IF you feel it thru the seat, it is more than likely a drivetrain issue. You would think they would check U-joints and such when balancing the driveshaft, but, ya never know.... Have a look. Jack up the rear of the car, in neutral, and start moving things. See if anything moves in a direction that you don't think it should. Turn everything, make sure that there is no binding. (brakes can certainly cause some trouble here.) Watch your wheels, not bent, or loose.

Have you rebalanced your wheels/tires? Do you have a caliper binding? (E-brake cable?) Pinion bearings? Axle bearings?

THese things can be fun (not!) to find.

Good luck.

 

i found out where mine is coming from. My torque arm bushing is none existant and it is allowing it to move up and down while i am driveing. i haven't replaced the bushing but i am for sure that is what it is because the hole i cut in my floor for my shifter i made to big and i had a friend look through there while i was driving and he said that the torque arm was bouceing up and down real bad. When i get that replaced I will let you know if that takes care of my problem.

 

colonboy, did you do anything else around the same time? For example I changed my trans mount and had vibrartion, learned through this board that if the crossmember isn't in the exact position the result will be vibration.

Looked in the service manual, here are some suggestions:

- Rouch wheel bearing
- Tore imbalance
- Worn universal joint
- Driveline angles incorrect
- "Mis-indexed" propeller shaft at pinion yoke
- Pinion yoke runout too great

Hope these help