Please help with Vibration Problem

**John_Shughart** · 05-01-2008

oK please let me know if you have any input or advice but here is the problem.

1. I have put a new suspension set up on my 04 GTP. i used Eibach springs and KYB struts on the rear. also put in a GM performance Sway bar and GM performance Trailing arms on the rear.

2. After putting it down i had a vibration. so i have performed the following.

1.Balanced All tires. One was bent.
2. replaced the bent wheel. Vibration still there
3. Had the Stealership do a super wam-a-dine balance test on the wheels. Turned out i had another bent wheel. Jackasses that replaced the first one replaced it replaced the wrong one. ordered a new wheel they put it on and the vibration is still there.

I have no idea what in the world could be causing this and im at my witts end at trying to pin point. so please if you have any input fire away.

**SyntheticShield** · 05-01-2008

Does it occur at a specific speed or between certain speeds and then go away?

I dont know for sure if the Eibach spring lower or how much if they do, but its likely it could be from the lowering if you have done that. Check that first if you have.

Absent that, I chased a vibration on mine that happened between 45 - 55 or so and then went away, or at least I felt it no more. Three four wheel aligments later, new lower and upper motor mounts, new tranny mount, new tires, etc I found out it was caused by my axle shafts.

**VinnieGTP** · 05-01-2008

Here's your answer for sure:
ClubGP Message Forum troubleshooting

And you can get them here:
http://www.grandprixforums.net/f51/m...back-1107.html

**Sabrewings** · 05-01-2008

Lowering screws up the geometry of your drive axles. I really wish more people would research lowering their car before doing it, because this comes up a lot.

You have to restore the factory geometry of the axles. There are a few methods, but that's the only solution. They can't be modified.