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

 

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

 

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.

 

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!

 

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

 

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 . 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.

 

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.

 

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