Above about 65 mph my car vibrates pretty badly. It isn't so bad if your accelorating, but when you let off its really noticable and annoying. I'm pretty sure its got to be the steel driveshaft. I had it rebalanced and it made it a little bit better but it still sucks. I was wondering if it could possibly be the 12-bolt somehow causing it. Although, I think what I will probably need to do is get an aluminum driveshaft from a ls1. All I can figure is that since i have the m29 tranny and 4.11's maybe the driveshaft is spinning a lot faster than a steel one was ever meant to. I just wanted to see what ya'll thought before i drop $150 on a new driveshaft.

thanks

 

IF not the driveshaft or tires, then I think a bad U-joint could also cause this?

 

Are you guys the original owners?

If not, has the vibration always been there?

If you ARE the original owners, have you had the clutch replaced?

 

What kind of 12 bolt do you have? If its a moser your DS will need to be shortened. I had the same problem after a car accident,the DS was a taco shape, replaced it with a aluminum shaft, and it helped but still had the problem. Ends being it's my trans. Check the outputshaft on your trans to see if it's leaking.

 

I have a similiar vibration. I didn't have this problem until I installed my Moser 12 bolt with 4.11's. I have a steel driveshaft that was shortened. I was going to try and get a custom aluminum shaft made, (about 350.00), and am hoping that will solve the problem.