put in 8 3/4, now have vibration

Supershafts said

You need to give more detail on the vibe, does it come in at ___ speed and it gets better or worse as speed increases, does it ever get better after a certain speed....

Now why the shaft was shortened is beyond me, if you couldn't get the shaft in then you had a reason to shorten it, otherwise the instruction you were given to measure from where to where when you have the shaft is also beyond me why that was done.


I can't tell you how many people shortened a shaft and then had to spend more for a longer slip or retube, or in many cases make a new one..

i need more detail of whats going on.
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Thanks for your reply Supershafts. The shaft had to be shortened because It was the original shaft, designed for the original 7 1/4 rear end. After installing 8 3/4 rear end the shaft was too long and would not fit.

And I also put in new axles and new brakes.

After all that the vibration started: it begins as a fine vibe around 40-45 mph then gets more coarse and stronger as I get faster. By the time I hit 70 its pretty bad, enough to disourage me from going any faster. If I'm going down a big hill and coast in neutral the vibration is really bad.

I pulled the axles back out, they looked great, then re-installed. Since then I've been messing with the rear u-joint. I just don't know if I should focus on the joints or if the short shaft is the problem. Thanks for all your help!