Vibration
 

Heres the deal. When i get up to speed ( about 90mph) my car shakes really bad. Last time this happened rear seal from tranny fell out. Which shook even worse. Ive had new drive shaft made, new ujoints ect. Ive jacked the car up and ran it to 130mph with no shakes at all? Its got me baffeled to say the least. Could it be a bent rim? By the way its a 65 skylark 383 stroker, 4 link prostreet. Thanks

Tail shaft bushing? :?
Excessive drive shaft deflection, may only happen under a load or out of balance? :?

Forgot
 

A note i forgot. Motor and trans are solid mounted, no rubber. Could this be the problem of vibrations? Could i put rubber under tranny? Or do i need rubber on engine mounts also?

Mine are solid mounted and I have no vibration. When you said the trans seal came out that made me think tail shaft bushing.

It maybe that your yoke is not far enough up in your trans. I think that maybe it. JMO.

yoke
 

How far is the yoke suppose to be in? When i have car lifted in rear i get no vibes at all. Does this change pinion angle? Does it shove in yoke farther?

Sounds like the driveshaft is too far in causing a bind when its on the ground,might be some thing you might want to check out

Ok there you have it not enough or to much. I was told you should be 1/4" from bottomed out in the tranny but you need to call and check that out. If you have a inch or more from bottoming out now I would say your to short. Take the driveshaft lose from the rearend and slid it in an out to see how much play you have and let us know.

I got to thinking today, that when i have rear of car off the ground, i get no vibrations at all. Im talking an inch off the ground and motor s running at 130 mph. This doesnt change anything except tires not touching ground. Took both tires to shop and low and behold one was 2.5 grams off, other was 1.5 grams off. This baffeled me because no weights had fallen off, but tire pressure was 26 lbs in each. Originally i had 35 lbs in each 5 months ago. By the way yolk was within 1'' range give or take. Talked to tranny shop today he said there is no magic number for yolk being in to much or not enough. By the way car doesnt vibrate at all since tires were rebalanced. So im thinking if vibes come in agian i will just keep 26 lbs of air in each! :D

That's what I like to see another happy man. Good job on your find.