rossp

iTrader: (3)

I finally finished up my 60 to 80 swap. Everything is good except for anything above 50mph I'm gettin a really bad vibration, bad enough that I don't feel comfortable driving any faster to see if the vibration will go away. One thing I did notice with the swap was the weight on my stock driveshaft was hitting the ds loop on my spoon torque arm crossmember, so I had to cut the loop off for the time being. I'm assuming this means the rear of the trans is lower than what the 60 was. If this is the case would this cause that bad of a vibration?

wht/73

Pinion angle.
Why is the trans so low?
My Gforce xmember made the reat of my trans drop with the 350 mount in it.
So much so, the rotor hit the cap in my distributor!
I had to get a urethane one that was an 1" thick plus a 3/16" shim to get it off the firewall!

rossp

iTrader: (3)

I'm using a bmr crossmember. I'm guessing it was just built to a slightly different height than the factory crossmember. My main concern is if this little bit of being out could cause a bad vibration

stock ta

iTrader: (1)

If you switched to a polyurethane transmission mount, that could be your problem. I've seen where they will cause a vibration.

rossp

iTrader: (3)

I still the factory rubber mount. I picked up a digital angle finder this mornin and will try to get my trans and pinion angles measured this afternoon.

rossp

iTrader: (3)

Checked my angles this morning. Measured off of the balancer the Trans is pointing down 2.4 degrees so I adjusted the pinion to 1.5 degrees up off of the torque arm mount at the differential. Still have the vibration and still just as bad. I'm gonna pull the driveshaft and rotate it 180 degrees and recheck pinion angle at the yoke.

rossp

iTrader: (3)

Verified the pinion angle at the yoke and it's good. Rotated the driveshaft 180 degrees and the vibration got worse. I'm at a loss here now.

clinebarger

2.4 degrees down is to much for our cars.....Especially lowered ones. You want the drive shaft to be level or sloped down at/to the rear.

Did you have the shaft re-balanced after the yoke swap? Swapping yokes can throw a drive shaft way the hell off!

rossp

iTrader: (3)

2.4 degrees down is as high as i can get the trans up. I already have 1/2" spacer under the mount. I didnt have it rebalanced. I wasnt aware the yoke would throw it off so i may need to check into that. I also noticed I have right at 1.5" of slip in the yoke at ride height.

wht/73

That would be my next move.
When I had my DS shortened and the new yoke installed new solid joints and balanced.