Over 110mph horrible vibrations, but everything is fine at 80-90.
 

:confused:

What could cause such a high speed vibration when at any speed under 100 everything is fine. I mean, it is a real good vibration, enough that is slows me down because of it.

Any ideas?

-James

Re: Over 110mph horrible vibrations, but everything is fine at 80-90.
 

Check your alignment, tire balance, air pressure. Could be a lot of different things. I wouldn't believe any of it would be serious.

Re: Over 110mph horrible vibrations, but everything is fine at 80-90.
 

I have something similar in my firehawk, and my 96 ta. in my 96, it around 100+, and my firehawk, 90-95+. Ive read that the stock lt1 driveshaft is usually the culprit, and a ls1 driveshaft swap is the cure.

Re: Over 110mph horrible vibrations, but everything is fine at 80-90.
 

i had a vibration like that before,..

ended up being my transmission (stall) was toast...

so if you have a stall or any work done to ur tranny. That could be it. also another thing to check into is your driveshaft!

Re: Over 110mph horrible vibrations, but everything is fine at 80-90.
 

have you had the driveshaft off any time recently? try turning it 180* and see if this helps.

Re: Over 110mph horrible vibrations, but everything is fine at 80-90.
 

Have you changed the tranny mount? If so, I hope you didn't use an ES mount, they have had issues since the mount seems to be out of spec with the factory mount. After my factory mount exploded, I changed to an ES mount which caused my teeth to chatter at higher speeds :D . If this is the problem, go with a factory LS1 style which has the "interlocking" design in case you break it (unlike the factory LT1 mount).

The LT1 driveshaft also has some balancing issues which could cause vibrations. I went to the 1LE shaft.

Re: Over 110mph horrible vibrations, but everything is fine at 80-90.
 

If you're using a poly trans mount, swap it out for a rubber LS1 mount. This fixed my high-speed vibrations....the car was unbearable on the highway and got worse as RPMs/MPH increased.

Re: Over 110mph horrible vibrations, but everything is fine at 80-90.
 

I had that problem, it was my steel driveshaft. Bought a aluminum and its fixed.