Knocking noise...just read this.

Okay 99 XJ, 125,000 Miles, 4x4, heavy duty leafs, nothing crazy......At 30 MPH on the nose, my Cherokee has this shake/knock. Got under the Jeep lefted the rear up turn the truck on. Looked at the driver shaft while it was spinning and didn't seem like the driveshaft was bent. Put the truck back down and started twisting and pulling on the driveshaft, no problems there either pretty solid. I know most are going to say u-joints but it doesn't seem like it. I just replaced the brakes about 5 months ago, just got new stock tires and rims from a friend cuz I thought I had a bad rim. New UJ on the front, new Timken bearings on the front, and still the knocking is there, only when I apply the gas does it show up. coasting down the road doesn't really show the vibration as much. Any question ask, I appreciate the input though....needs some ideas.

Might be axle wrap causing you rearmost ujoint to bind under load

Have you checked your trans and motor mounts lately?

I am having the same exact thing going on with my 2000. 3-4 inch lift, rebuilt front end( everything) and new tires that balanced perfect. I just replaced my 231 with a 231 sye. Everything was perfect before I did the swap, but now when I hit the gas, I here a knocking sound too, sounds just like a bad U joint but all of them are good. I bought this t case used from somebody, and they said it could be the difference between the 8.25 rear end and the dana 35, and that the driveshaft splines could be bottoming out causeing this knock. With the driveshaft out of the axle pinion, it can still slide about an inch forward, just enough to clear the yoke. I have no idea what else it could be, please help!

I recently read somewhere on here that '96+ had a TSB for these sorts of problems. My son's '96 Classic has Up Country with, I believe, a 1"lift. It sometimes will have an odd shimmy at low speed, low to medium power, say when climbing a hill, still in 1st or 2nd. Apparently the rubber covered slip yoke is very intolerant of a u-joint angle of more than a few degrees. I'm going to see if I can find a TSB on this situation.

I don't know where tranny mounts are or the t-case mounts are. I just don't know why it only really happens at 30 MPH and then when I get onto the highway and do 60-65. I don't speed in the Jeep, gas is too expensive. The u-joints are old. what the best way to change the pinion angle??? Shims??? I don't think mine has changed but it's had this problem since I got it. but it didn't do it when I was going 30, that came about after I added the leaf springs. hopefully there is something about a TSB. I'm very interested to know now.

anyone else heard of the possible TSB for something like this????anyone got a link????

bump. new rims and tires, balanced and 4 wheel alignment. had the mechanic look at the mounts on the tranny and t-case, said they looked good. motor mounts good as well. I'm thinking it's the driveshaft. let me know what you guys think

I wonder if this is a situation where greasing up the slip yoke helps? Have you pulled your driveshaft yet to check for U joints freezing up? I think you need to do that anyway to grease up the slip joint good.

haven't had the chance to pull the driveshaft there isn't play in the DS while it's sitting there, but going from reverse to drive or vice versa, it kind "slaps" not a lot. FSM said something about pull the DS out and rotating it 180 degrees and then re-installing it. U-joints looked okay but I'm going to replace them since I did the front ones this summer. Anymore things to look at while I'm under it this thanksgiving break????