Vibrations

I'm trying to find the source of a vibration. i have reason to believe its coming from the rear as when my parking brake was working if you pulled on it a little it would get much worse. i still need to rebuild my transfer case as its a bit noisy. but I'm not sure if that can cause this vibration.

one thing I have noticed is now all of my tires are cupped. front and rear. could this be a rim issue?

Cupping might be the rims, but I'd also double-check the ball joints and hubs as well - anything that might cause the tire to potentially not "spin true" might have an effect.

Can you replicate the vibration with the rear axle up on jackstands and turning the tires by hand? If so, you could try disconnecting the rear driveshaft from the diff and seeing if that changes things...

I recently did front axle u joints and the hubs in the front still felt great. as well as the ball joints.

this vibration has been an ongoing search for about 5 years.

I haven't been able to feel the vibration by just spinning the wheels. its kind of an oscillating vibration at around 60-70

You said you thought it was coming from the rear? If so check your rear u-joints and lube the splines!

One thing I have discovered that has really helped me is "driving" the Jeep on 4 Jack stands. I get the vehicle in the air and support on 4 jackstands (under axles at each corner) on level ground. Then put it in 4X4 with the lockers engaged. Then shift to drive and it will be pretty easy to see where the vibes are coming from. Might need to rev it up a bit to get up to the speeds you are having the issues. You can see pretty quickly if its driveline/driveshaft related or wheel/tire related. If it is coming from a specific corner, then take the tire off and see if that fixes it. Most of the time these vibes are tire/wheel related. But if the wheel is off and it still is vibrating then you know its a bad bearing, warped disc, loose U-joint, or bent axle most likely.

RCP Phx said:

You said you thought it was coming from the rear? If so check your rear u-joints and lube the splines!

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i swapped the shaft and did joints on it.

i have tried the 4 wheel off the ground. i'm going to have to try it again. could a drum cause this issue? I have changed the drums 2 or 3 times. but with my luck it still could be them.

the only thing i couldn't change is the diffs. or the rims. i'm just hesitant on putting new tires and rims on and then having the tires cup again.

I guess drums could cause it but if you've replaced them 2-3 times then I'd say its unlikely. Have you checked/replaced the rear axle shafts or bearings? I just discovered I have 2 bent axle shafts on my 29 spl C8.25 doing this...really wish the C8.25 didn't have C-Clips

i took one of the shafts out but at the time i was unable to change the bearings. its a non c clip axle and the bearings are pressed in. i now have a press and i think all the parts for it.

the one i took out looked and felt good at the time but i cant say exactly.

when i first got this xj it had a set of miss matched rims and tires that where all bald. and a different transfer case and i remember it riding smooth.