I recently purchased an 86 gt my first mustang, we replaced the clutch and a few other little tune up things, and now there's a vibration coming from the rear end that gets worse the longer you drive, all the wheels are tight along with driveshaft and mounts, any ideas what could be causing this?

 

any noise? did you make sure the u-bolts are tight? is the dog bone still on rear? did you check rearend fluild level? did you mark the driveshaft postion before you pulled it when doing the clutch? did you check for a crack in the rubber trans mounts?

 

There's no need to mark the.location of the driveshaft. It's balanced for a reason. Maybe a weight came off.

 

So, speed doesn't affect the vibration? Only the time driven?

 

1. There is noise its like a low rumbling almost like a subwoffer, the rear end does leak a little but i recently filled it.
2. Speed does effect the vibration but only to 70 then it stays the same, and some times when i first drive it in the morning it wont vibrate at all, then it slowy just gets worse then longer i drive it

i know i sound uneducated, but this is my first one, so thanks for all the help guys!

 

I would bet my money on your rear end. It needs rebuilt. But before you embark on a rebuilt mission.....

Check and see what gears you have in the rear and see if its stock..

 

Are the rear wheels/tires balanced?

 

Way back in 1986 when I bought an '84 Capri RS with an 8.8 traction loc rear, I got a flat on the rear right tire when I was about an hour from home, so I put the spare on and drove back.

Well, as it turns out, the spare had a different diameter than the tire that it replaced... this resulted in one wheel trying to trun faster than the other wheel the whole time driving home.... effectively burning out the clutches in the rear.

After that, the rear made the same sound you are describing.... would start out quiet, then get louder the longer I drove it... really made some strange sounds when making a turn.

Got new clutch packs and took care of the problem... bet you need to do the same thing.