flyingstick

My XJ has done this since I've had it but it's getting worse. It feels like I'm towing a trailer with a loose trailer ball. When I hit about 5-7 mph it will clank like it's just changed gears with a shift kit in it or like the U bolts are loose on the differential which they are not. No broke mounts or anything loose I can find.

Dan91

Sounds like a really bad U-joint, checked those yet?

flyingstick

Yep, replaced them when I did the gear change. I almost think it's the leaf springs bending when the rear end torques.

hankthetank

does it feel like the jeep wants to stop or slow down when this happens? auto or stick? lifted? maybe knock the drums off and take a look...dunno sounds weird. mine did that too but i changed out a bunch of things at once, track bar, brakes, u-joints, clutch then it was gone...

flyingstick

No it doesn't want to stop or have any kind of power issue. It's auto but doesn't feel like or sound like it's in the transmission. I checked the brakes. It feels like it's in the rear. Very similar to a broken motor mount but they're not. Could worn spider gears in the rear diff cause such a symptom?

hankthetank

yeah maybe if there is so much slop that it starts to bind, but im pretty sure if that were the case they would have failed already...bearings? i would get the back up on stands and start reefing on stuff, see if anything is moving. do you have limited slip in the back? check the leaf spring bushings and rear sway if you still have it. rear shocks too, mine make a bit of a racket. loose hatch? dunno dude hard to diagnose without feeling and hearing for myself, good luck.

Outlaw Star

Yes, a worn out or broken diff will cause noise.

flyingstick

I replaced everything in the rear and front differentials last year except the spyder gears because I was hoping to install either an aussie or Spartan lunchbox in the rear. It feels just like you have a diving tank lying in the back about 8 inches from the hatch that rolls against the hatch when you take off. I've had it up on the lift and i can't find any slack anywhere.
Thanks folks,
Don

Bluexj98

Shackle bushings?

flyingstick

Found it. The fuel tank was loose enough when I would take off it would slam when all the slack was out.

als98xj