Fevre

Noticed recently my Formula does the tell-tale bad u-joint clunk when I put it in gear and Saturday I noticed a new vibration at higher speeds, 70-90 mph. Can bad u-joints cause this? Have had cars in the past clunk but not vibrate like this.

Thanks

midwest-vette

Not sure about the u-joints but I had a trans mount coming apart causing a bad vibration. Might check it out.

my .02.
:seeya

Fevre

Will do. :thumbs:

Brettmc

I had a bad u-joint on my old 69 Camaro that caused a vibration.

Brett

goofygrin

um yeah

right before they let go and cause you to feel a mighty big thump in your butt.

I would check them out ASAP... :eek: :eek:

Fevre

Blows cuz I just started to tear apart the vette for a 383 transplant. Both are supposed to go to the track on Sept 23. Might have to get some NOS for my Sonoma Highrider. :lol:

Scooter70

Chris- Do the 3rd gens have a torque arm like the 4th gens? Check out those bushings while you're under there.

(I went to Milan Dragway with some buddies a couple of weeks ago without my car.... it's not fun)

Fevre

Matt

Yes is does. Guess I'll climb underneath it this weekend and hav a look see. The previous owner installed a 3.73 Auburn posi in it so I hope it is not that thing coming apart. I just noticed the loud clunk when shifting into drive a few weeks ago so I hope this is just u-joints.

toyvet1

After years of looking for high speed vibration on my 79. I finally tracked it down to a bad tail shaft bushing or worn front driveshaft yolk. You can see about a sixteenth(?) of a inch play in the front of the driveshaft. Enough movement to see deflection in the rear seal rubber. Just somethink to look at..

ddecart

Hey Chris, Crawl under and see if the driveshaft has ANY play in it at either end. If it does, that's not a good sign. Look for rotational and translational play (basically look for slop in any direction). My car has a poorly balanced shaft and it vibrates a good bit at 75+

Question though. Does it do it at that speed in any gear? i.e. is it tied to driveshaft speed or engine/trans speed?

Scooter70

IIRC, that clunk going into drive points to a worn torque arm front bushing as well. (It's been a while since I sold my Z28 so I keep up with them like I used to.) Think of it like our front diff bushing on the Vettes.... which we both had issues with last year (and both thought it was something else). Hope this one is nice and easy for you.

Fevre

Funny thing is my vette def has a worn yoke bushing but i am going to a 5 speed hopefully this winter so I just put it back together this last spring. It vibrates a tad but not as much as the Formula just startered doing.

I'll give an update once I get under it this weekend. Praying for an easy fix. :blueangel: :)

adam

Anyone have the spicer Ujoint part numbers for the rear half shafts for an 81?
I was searching the archives, but didn't find it...

Fevre

Well I think the vibration was a u-joint but the clunk def is not. One of the caps for the rear u-joint was not seated properly it was out a 1/4" too far and the c-clip that holds it in place was smashed a little. The u-joint was prolly off center that 1/4" and some of the parts showed signs of slight rubbing. Took it for a quick jaunt to 110 and most of vib is gone, might need tire and drive shaft balance. The clunk is from about 1/4 to 3/8" slop in the posi. Not sure what is 'normal' but I know that is too much. This might also be causing some vibration. Sounds like another winter project. :rolleyes: