Hey whats up guys.
I'm getting some vibration from somewhere between my T-case and rear axle.
It only vibrates when i'm driving around 50MPH and ONLY when i let off the gas pedal.And as soon as i ht the gas again the vibration stops. Maybe a U-joint?????
I did it a couple of times today while i was on the highway,and when it vibrated i held on to the T-case shifter and it felt pretty bad.
Maybe i should get my driveshaft balanced.
I went underneath to see if anything was loose...all tight.
Any ideas?

Jerry D

 

Did ya give the driveshaft a good shake at the trans and pinion to see if anything is loose? heck, on your truck you dont even need a lift to do that either.

Does it clunk if you go back & forth between Drive and reverse?

I found out my driveshaft was out of balance but it was because of the higher ratio on the ring & pinion making it spin faster. If you still have the same ratio as before it's probably unlikely that it's out of balance (maybe bent?). I wound up putting jackstands under the axle tubes and running it to find the noise. You might need to remove your tires for that unless you get it on a lift.

There's some good info in the tranny forum, check out a thread I started called "Who's done the tailshaft replacement?" Lotsa good info and a link to an article on diagnosing driveline vibrations too.

Good luck.

 

Thanks for all the help/info down at Tom's shop.

Jerry D

 

Update:
I had my driveshaft balanced today and sure enough it was off and out of round.
I put in 2 new U-joints....one was shot.
I'm also replacing the tailshaft bushing,seal,and bearing from the transfer case.
I also cracked the plastic speedo gear that rides on the t-case output shaft....so i have to wait until that comes in at Ford on friday

I'll let u know how it rides

 

I'm glad ya got that straightened out. I myself was amazed at how little it takes to get a driveshaft out of wack once you start spinning it really fast.

I'm sure that when you get it all done you'll be back to cruisin again.

Good luck.

 

UPDATE:

The Ford dealership finally got my part (speedo gear) so in she went....
Most of the vibration is gone.......but i think it's time for a custom crossmember.(thats the only thing left)
I might as well,i'm gonna go with a bigger lift this summer.And that is one piece that will have to be modified.

Thanks for all the help.
Jerry D