Ive been having this problem for awhile now..

When I WOT or even rev while the car is rolling & in neutral and get to ~6k the car begins to vibrate pretty bad. It is particularly bad in 3rd gear WOT. When I get the RPM up range my seat feels like a vibrator!!

NOTE: the car does also vibrate when under load below 3k rpm in 2nd, 3rd 4th gear but not so much 5th.. I have a Diff brace also but I took it off and didnt cure anything. I think its related to the tranny or engine since it still does it when in neutral.

Thanks for the help guys.

 

Have you checked your motor mounts? PPF?

 

I have noltec mounts which are new along with the garfinkle brace. Removing the brace didnt change anything as well. Ppf seems fine also.

I did swap trannies recently and i noticed the shifter sits alittle more to the right. Im thinking my tranny may not be aligned properly?

 

U joints????

jerij

 

U-joints would not vibrate in neutral. Most likely you messed up something when changing the tranny. I would think tranny or clutch since that was what you worked on last. Possibly the pilot bearing got tweaked on installation.

 

Since it occurs at high rpms, I think its load dependent and in direct contact with the motor. maybe the pilot bearing but I would think a faulty pb would cause other affects. Could be clutch, ill have to inspect it.

I still have a gut feeling about something else. I will try to get wrenching this weekend

 

It isn't load dependent if it does it in neutral.

 

You probably have something out of balance in the engine/trans assembly. I would suspect the clutch might be out of balance. Did you replace that when you R&R'd the trans? How about the flywheel or counterweight? Anything change there?

 

Im using the same counterweight as from before when I had a spec clutch. When I changed the tranny I installed a ACT S/S clutch.

 

Then that's the first suspect. Make sure it is correctly balanced and not, somehow, off center.

 

alright guys, I started to work on this issue last week. im starting with the more simple possibilities and working my way to more severe/complicated.

I correctly clocked my noltec mounts and no cure..
I am loosening up my ppf and tranny and want to correctly align them, (my tranny is tilted slightly to the right)

If ppf adjustment dosent work, I am going to take out my tranny and inspect the counterweight, flywheel etc. After that the only possibility is a unbalanced engine. my motor has 50K miles and its originial pulling good vaccum. I hope its not the motor.