Im posting this here because I need to get some results for this problem.

My car has been shaking violently after my LT1/M6 swap.

Ive changed just about everything in terms of suspension and powertrain, and I dont know what could be causing it to shake so bad.

Ill explain when it is happening:

I first noticed it when I would get to 80 mph, and let it cruise. While it is crusing, and i pop it into neutral it starts to shake, and what im feeling it body roll from driver rear to passenger front, and passanger rear to driver front. at that point, when i pop it into 4th the car stabilizes.

next, i started noticing it big time when I went up and down a steep bridge. IT would start while I was going down the bridge and let off the gas...and again, pressing the gas stabilizes it more.

please...i need a solution to this.

Some background info.
KYB's in the rear, Stock DeCarbons in the front.

eibach lowering springs

C6 wheels (18s front/ 19s rear)

stock panhard (kept on from v6 through swap: my understanding is that is was universal)

stock lca's kept on from v6 through swap: my understanding is that is was universal)

1 piece driveshaft (lt1)

new sway bars new mounts

new tranny mount.

anything else please let me know.

I would like to get this problem resolved, so anythign is helpful.

 

I understand your feelings that LT1/LT4 Engine Tech has a lot more traffic, but that's the problem with posting off-topic.... it forces the valid posts off the page quicker on a forum that's already overloaded.

Moving to "General......"

 

Alignment ok? Driveshaft may be out of balance. Flywheel?

 

yikes i wouldnt even want to imaging the driveshaft being misaligned at 80mph, that could be an ugly seen not to scare you..

 

U joints? My S10 had the incorrect U joint put in and would vibrate violently at 2k rpm. Give that a try.

 

I've figured out how to better explain the vibration.

It feels sorta like turning the wheel from left to right quickly at high speeds...the car is going straight, but it is moving up and down on its sides...do you guys follow???

 

Get yourself to an alignment shop immediately.

 

you think its an alignment issue????

my power steering pump is kinda going bad too...any connection?

 

All of that vibration can F up lots of stuff. You have new suspension -- yes, I think it's alignment. I could be wrong, but you have new suspension, so you should get it checked anyway.

 

thanks, i need to get it handled...

what about u joints???? anything in that department?

 

okay...Update...

Ive triggered whats really going on. Ive learned that the swinging from side to side occurs from the shifting of 3 to 4...does that help any?

 

Sounds like an alignment issue to me as well...Was thinkin improper wheel balancing at first but this sounds a little more serious.

Take it to an alignment shop soon and get it checked out,theres gonna be some changes to the suspension after going from a V6 to a V8.

 

ill be doing so this weekend. thanks again guys.