95 XJ Pulsing Vibration At Highway Speed

I've been trying to track down a pulsating vibration that starts at about 70mph and worsens. Its unclear where its coming from. The vibration goes away if I shift the t-case into 4HI. Here's the jeep's specs:

95 XJ with 4.0
3.5 RE Super Ride lift
Advanced Adapters Slip Yoke Eliminator
Tom Woods rear driveshaft (recently checked for balance at a reputable shop)
Stock front driveshaft (recently rebuilt and balanced at a reputable shop)
Yukon 4.56 gears (installed at shop)
32 inch Mastercraft Courser MXT tires (balanced multiple times)

Details: (took place over a few years)
I first noticed the vibration after the gears were put in. The vibration would start at around 60mph. The vibration is a loud pulsating vibration that seems to come from everywhere under the jeep. I took it back to the shop and they didn't think it could be the gears. I then had the tires balanced and that didn't help. Took the front and rear driveshafts to be inspected and rebuilt/balanced as necessary. The front was rebuilt and balanced and the rear was already good. After install no change. I sent pictures of my rear driveshaft angle to Tom Woods and he thought the angles looked good. I left it alone for a while and ended up moving across the country. Some time later I took it to a local 4x4 shop and they noticed that the transfer case rear output yoke was a bit loose, so I inspected the yoke splines for damage (all good) and torqued it and the front yoke with my impact wrench. This did have an effect and the vibration now starts at about 70mph. I took it to a reputable transmission shop and they put it on a lift and got it up to speed in the air and tried to listen for anything. However, in the air the jeep would not make the vibration. The shop couldn't identify anything wrong with the tranny or t-case. I'm at a loss for what could be causing this. Does anyone have any ideas? Thanks.

Put it on an alignment rack that lifts the axles up, not the body, and listen for it. Or just four stable jackstands would work.

One simple test you can perform is to remove one driveshaft and then take it out for a spin. See if anything changes. If not, try it with the other driveshaft removed.

One thing to pay real close attention to is the centering ball. I have taken a driveshaft in to have it serviced and got it back with all new U-joints and balanced, but nothing done about the centering ball (which had a very poor condition wiper). Don't count on a shop to have done anything you didn't expressly tell them to do. And even then, verify.

I removed the rear driveshaft and the vibration was still there. I put it back and took out the front driveshaft. Vibration disappeared. I figured the previous shop must not have balanced it right. I then took the driveshaft to a local driveshaft shop (very reputable from what I've heard) and they rebalanced it. The centering ball is in good shape. I put it back in the jeep and the vibration is still there. In fact it went back to starting up at 65mph.

Check the front output bearing in the tcase. Grab the installed Dshaft at the tcase and check for radial play. For shits and giggles do it at the diff too.

xcm said:

Check the front output bearing in the tcase. Grab the installed Dshaft at the tcase and check for radial play. For shits and giggles do it at the diff too.

Click to expand...

There is a slight amount of radial play at the transfer case. I'm surprised the transmission shop didn't catch this.

It sounds like you are making progress.

Keep us updated.

A good tcase rebuild should get you sorted out.

Well I replaced the front and rear bearings for the front output shaft and also replaced the tcase chain while I was in there. Unfortunately the vibration is still there. It doesn't pulse as much as before and it seems like it is coming from somewhere up front. I checked the ball joints and front u-joints and they're good.

I just went through this same problem. I rebuilt my t case and had my drive shafts balanced. It still vibrated after all that. I had extra front drive shafts and kept swapping them out till the vibration was gone. I think your vibration is still from your front drive shaft.

Well I threw in the towel and bought Yukon manual hubs. Solved the problem but expensive.

That's got to be the most expensive band-aid ever!!!

It's probably the front axle pinion angle

My money is still on the driveshaft, but since he thinks he fixed it we wont know until something else happens!