Help with rear driveshaft/diff

[Ccjeepma]

Ive got some serious vibrations coming from mid to rear of my kj. When I inspected the driveshaft to check for faulty ujoints I could NOT get any play in either joint but at speeds of 30+ i feel some serious vibrations and and occasionally a clunking. Also if i come to almost a complete stop but have to then apply gas before coming to a complete stop it feels like something comes unattached underneath and then reconnects or like a yoyo/train. Any ideas?

 

[tommudd]

How are the U Joints first thing ?
Looks alone doesnot tell how they are
Take it for a ride 20/30 minutes , pull back and stop and put hand near each u joint , if hot it is bad
Next check backlash in rear diff
Then

 

[ngkdum]

I had a very similar case and the clunking on takeoff would be so bad that I thought the rear end was falling off. Turned out to be the upper control arm. The center bushing on the arm was almost completely disintegrated. I could actually see the rear end rotate when I rocked the vehicle back and forth. Hope this helps.

 

[sleazy rider]

Yup, check the rear axle upper control arm bushes.

 

[KJowner]

Also check the tyres are still round, I've had horrible vibration from a warped tyre.