DaveM
NAXJA Forum User
- Location
- California
Hi, folks. This is my first post, been lurking for a while. I've searched every driveline clunk thread I can find but haven't found an answer to a problem I'm having, so here goes.
I have a 90 XJ, 4.0L, AW4, NP242. Has 223,000 miles on it, I bought it a little over a year ago with 189,000 miles on it. Currently has BFG AT's, 215/75R15 on factory alloy wheels. Basically stock, but about 6 months ago I swapped in Grand Cherokee V8 front coils, and added two additional stock leafs to my slightly sagging original leaf packs. I cut the eyelets off the main leaf of the donor pack, and added that plus the second leaf to my original packs. Front wheel center to bottom of fender flare now 19.25", rear is 18.25 inches, so about a 1.5" lift. Had no problems after this lift, no noises or driveline vibrations.
About two or three months ago, during normal acceleration at about 25 or 30mph, I heard/felt a loud clunk, seems like from the rear driveshaft area. It sounded/felt like what I would expect if something like a ujoint bound up and then suddenly let go. It doesn't make the noise all the time, and I haven't been able to pinpoint it with any specific event, shift point, etc. It never makes the noise at freeway speeds, only normal, surface street driving around 25-35mph. Always happens driving straight, light normal acceleration. If I let off the accelerator, it stops, but will often but not always clunk again as soon as I press the gas. Again, not hard acceleration, but just normal driving. I've even tried to be as easy as possible on acceleration, and it still clunks sometimes. I've tried it in both 2WD and full-time 4WD, and it clunks in both modes.
My first thought was ujoints, so I dropped the rear shaft and could feel no play in either joint. I pulled the two accessible caps off the rear joint and could see no problems there. Reinstalled the drive shaft without replacing ujoints and clunk was still there.
As it happened rather infrequently I lived with it for a while since I didn't have time to work on it, even made a trip from CA to Wyoming with it. In the last month or so the clunk has been more frequent, and now sometimes does multiple clunks in succession, same speeds as before, same conditions. They are loud, banging clunks.
I've had a wrecking yard Dana 44 waiting to be installed, so last week I decided to swap that in. After install, still the same clunking. Old rear axle was Dana 35, open diff, 3.54:1. Replacement Dana 44 is 3:54:1, factory limited slip. I did not go through the 44 except a fluid change, but I got the same clunk with either axle, so don't think it's in the axle.
I then checked the posts here again, and checked my motor mounts. Saw cracking on both mounts, so replaced them and the trans mount. The left hand motor mount was in two pieces, the right hand had just started to crack. The trans mount was quite squished compared to the new one, at least an inch shorter than the replacement. Thought this was for sure the cause of my problem. Replaced all three mounts, clunk still there.
Today I replaced the ujoints on the rear shaft. I inspected the old joints after removal, still could not see anything wrong with them, but put the new ones in anyway. Clunk is still there.
I've checked the torque on the rear spring ubolts and they are tight. I have not yet replaced the rear shocks, but have inspected them rather closely, top stock bar pin mounts appear fine, not loose, bushing not loose, bolts tight.
Any ideas?
Sorry for the length of the post, but I wanted to get all the info out there.
Thanks in advance for your help.
I have a 90 XJ, 4.0L, AW4, NP242. Has 223,000 miles on it, I bought it a little over a year ago with 189,000 miles on it. Currently has BFG AT's, 215/75R15 on factory alloy wheels. Basically stock, but about 6 months ago I swapped in Grand Cherokee V8 front coils, and added two additional stock leafs to my slightly sagging original leaf packs. I cut the eyelets off the main leaf of the donor pack, and added that plus the second leaf to my original packs. Front wheel center to bottom of fender flare now 19.25", rear is 18.25 inches, so about a 1.5" lift. Had no problems after this lift, no noises or driveline vibrations.
About two or three months ago, during normal acceleration at about 25 or 30mph, I heard/felt a loud clunk, seems like from the rear driveshaft area. It sounded/felt like what I would expect if something like a ujoint bound up and then suddenly let go. It doesn't make the noise all the time, and I haven't been able to pinpoint it with any specific event, shift point, etc. It never makes the noise at freeway speeds, only normal, surface street driving around 25-35mph. Always happens driving straight, light normal acceleration. If I let off the accelerator, it stops, but will often but not always clunk again as soon as I press the gas. Again, not hard acceleration, but just normal driving. I've even tried to be as easy as possible on acceleration, and it still clunks sometimes. I've tried it in both 2WD and full-time 4WD, and it clunks in both modes.
My first thought was ujoints, so I dropped the rear shaft and could feel no play in either joint. I pulled the two accessible caps off the rear joint and could see no problems there. Reinstalled the drive shaft without replacing ujoints and clunk was still there.
As it happened rather infrequently I lived with it for a while since I didn't have time to work on it, even made a trip from CA to Wyoming with it. In the last month or so the clunk has been more frequent, and now sometimes does multiple clunks in succession, same speeds as before, same conditions. They are loud, banging clunks.
I've had a wrecking yard Dana 44 waiting to be installed, so last week I decided to swap that in. After install, still the same clunking. Old rear axle was Dana 35, open diff, 3.54:1. Replacement Dana 44 is 3:54:1, factory limited slip. I did not go through the 44 except a fluid change, but I got the same clunk with either axle, so don't think it's in the axle.
I then checked the posts here again, and checked my motor mounts. Saw cracking on both mounts, so replaced them and the trans mount. The left hand motor mount was in two pieces, the right hand had just started to crack. The trans mount was quite squished compared to the new one, at least an inch shorter than the replacement. Thought this was for sure the cause of my problem. Replaced all three mounts, clunk still there.
Today I replaced the ujoints on the rear shaft. I inspected the old joints after removal, still could not see anything wrong with them, but put the new ones in anyway. Clunk is still there.
I've checked the torque on the rear spring ubolts and they are tight. I have not yet replaced the rear shocks, but have inspected them rather closely, top stock bar pin mounts appear fine, not loose, bushing not loose, bolts tight.
Any ideas?
Sorry for the length of the post, but I wanted to get all the info out there.
Thanks in advance for your help.