Vibration while accelerating

[seanp]

My 83 Jimmy has a pretty good vibration but only while accelerating. It is smooth once you get to speed. The u-joints and trans. mount seem good.

And i don't know if this is related but the slip yoke seems to stick out of the t-case too far. But my Jimmy is stock with no lift.

 

[Stoopalini]

Sounds like a typical U-joint problem ..... how do you know they are good?

Thomas.

 

[seanp]

I put it in neutral and shake the d-shaft. I guess it wouldn't hurt to replace them, thier cheap.

 

[Blue85]

I have been chasing the same problem for years. At speeds below 30, while accelerating, there is a slight shaking. It is the same regardless of throttle, so it is not axle wrap. I have set the pinion at different angles and the problem changes, but never goes away. It just isn't bad enough that I have made the move to the real solution: CV driveshaft. I believe the real problem to be the inherent play in the slip yoke and T-case to cross-member mount. I think this prevents the forces at the two U-joints from completely cancelling out. I think that a fixed yoke T-case could also help, and to a lesser extent a brand new slip yoke.

I have had "wrong" U-joint angles before and that caused vibrations at pretty much every speed.

I hope your problem turns out to be simpler. Check the U-joints and U-joint angles. An angle finder is cheap. Some people fix it real quickly by lowering the T-case, if you're not opposed to that.

 

[Stoopalini]

His Jimmy is stock sitting on 31's, which is why I said it's most likely the U-joints.

I hear you on the 'tracking a vib down' thing. I can't seem to get rid of a small vib on my truck either. I've tried lowering the t-case, new u-joints, etc .... next thing for me is to start playing with angle shims. Since I'm only 2 1/2" up, I don't see how I would need a CV setup ....?

Thomas.

 

[Stoopalini]

Putting it in neutral and shaking the d-shaft will tell you if it's bad, but only if it's real bad. If it's just starting to go out, the play in it may only be apparent under extreme force, like when accelerating /forums/images/graemlins/wink.gif

Thomas.

 

[Grim-Reaper]

If your stock hight ...J-joints and have the shaft ballanced. I had a Toyota Supra do that. The Supra is IRS. The U-joints have less then a 1 degree operating angle. I did the old neutral shake and twist it routine I know 10 times.

I was convinced the diff was eating it's self. I started to pull the diff assembly out. Dropped the drive shaft and found the bad U-joint.

 

[seanp]

Who woulda thought it, but the new u-joints pretty much cleared up the vibration. /forums/images/graemlins/grin.gif Thanks guys.

 

[Stoopalini]

Glad to hear you got it resolved /forums/images/graemlins/grin.gif and thanks for letting us know ...

Thomas.

 

[Confedneck]

never had a vibration in my truck, and checked out the ujoints when i bought it..hell they were original, thought it would be a good idea, nice and tight..until they started squeaking...i would have sworn it was the rear ujoint (by the pumpkin), but i replaced them both anyway...truck drives so much smoother now..just thought id let you know, a little preventative maintenance almost never hurt anyone..unless you get the waxy plastic crap on ya..LOL