2000 Disco 2 - My rear end started making a loud thump while driving yesterday. Started small then got louder and louder and I could feel it. Felt and sounded like a flat tire but they are fine. It completely goes away when I'm turning either Direction. But feels like I'm driving over speed bumps when going forward. Drive perfectly straight though, I also did some rolling in neutral but still thuds. I crawled under her and everything looks nice. Once it warms up a tad I'm going to start pulling things apart but was looking for guidance on what this might be?

 

I hope this isn’t your case but I had a Suburban that did something like what you’re describing. When I removed the diff cover I found large chunks of gear teeth at the bottom. I hope you find something much simpler.

 

Check the Rotoflex, the big rubber donut, you may need to pull it if teh diff side is shot. Also rear drive shaft,they do fail.

Other than that I agree with @Harvlr dump the diff fluid and check for metal

 

Watts link bushings or trailing arms bushings or sway bar bushings or links could have given out.

 

That makes sense. Thanks, I did a little searching on that and think (hope) it may be a suspension thing. If I rock the parked truck side to side I kind of hear a small clunk.

 

Which factor affects it more -- vehicle speed, or condition of the terrain?
If it is relatively calm when coasting in neutral on a paved surface, but knocks loudly when you go over a bump, I would lean towards suspension or Watts linkage. If the frequency of the knocks increases as the vehicle speed increases on a paved surface, I'd look at the rotoflex or driveshaft.

 

Upon further review - sway bar links it is. Thanks for the tip!

 

It was a steady thump that felt like every well rotation, the knocks sped up as I sped up for sure. . Knocking loud the whole time, then silent on turns. Bumps didn't seem to affect it. Wondering it this broken link would cause that.

 

I was only meaning my diagnostic suggestions as a starting point for places to look. I would say that a broken link could be a likely cause, although I'm no suspension expert.

 

Yes, that sway bar link wouldn't normally make a noise while just moving forward. It would only clunk if it made contact...and it wouldn't be something continuous, normally. Plus, l don't see any contact marks on the two peices. If you have a "rolling clunk or knock"...l'd still be looking at watts link (mounted on rear of axle housing) or roloflex/driveshaft. If nothing jumps out at you there, then drain axle fluid and look for chunks of metal. Check your front driveshaft also, noises can travel underneath.