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40-55mph vibrations tried replacing the U-Joints didnt help.

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Plays For Jeeps

NAXJA Forum User
Location
Allentown PA
Its werid. The vibs happen randomly. Meaning that they happen sometimes while coasting, sometimes while under accel., sometimes while braking, but always between 40-55mph and always violent when it does happen.

Lastnight I replaced the rear U-joint. It didnt seem to be bad but it still needed replacing.

I checked the tire pressures and they are all at spec.

Any ideas guys?

EDIT: Sorry almost forgot.

96 4dr, 3.5 RE lift, SYE eliminator, P-231 transfercase with Advance Adapters SYE modification, on vacuum disconnect HP30 front from 89 XJ,& BFG AT's 31"x10.5"
 
Last edited:
what kind of driveshaft?

pinion angle should be 2 degrees below d.s. angle.
 
Check the slip in the front shaft, this has always been the first place I go when I get a vibe.
 
Plays For Jeeps said:
^Noob question, but does the front shaft even spin if im in 2hi? How do I check that slip you speak of? Thanks!
Click to expand...

Yes, the shaft will turn while in 2hi. The D30 doesn't have lockout hubs. That means the axle shafts turn, the R&P, and the DS.

To check the slip yoke, remove the front shaft, and see how easy it slides back and forth. It should have some resistance, due to the seal. If it feels ok, grease it, and reinstall shaft. Also check the U joints while you are at it.
 
how about tire balance.....TREs, Ball Joints, Trackbar bushings......
 
CanMan said:
Yes, the shaft will turn while in 2hi. The D30 doesn't have lockout hubs. That means the axle shafts turn, the R&P, and the DS.

To check the slip yoke, remove the front shaft, and see how easy it slides back and forth. It should have some resistance, due to the seal. If it feels ok, grease it, and reinstall shaft. Also check the U joints while you are at it.
Click to expand...

His front shaft doesn't turn. I you read his sig it says " vacuum disconnect HP30 front from 89 XJ" so only the shafts and the spiders turn. Unless he has a locker he didn't mention...
 
try your sway bar/trackbar bolts at the diff and the chasis, i had the same problem, replaced the lca bushings help out a little but it would still do it at the end the bolts of the track bar where loose at the point where they hooked up to the chasis, got them tight and the problem was fixed hasn't done it yet.
 
TNT said:
His front shaft doesn't turn. I you read his sig it says " vacuum disconnect HP30 front from 89 XJ" so only the shafts and the spiders turn. Unless he has a locker he didn't mention...
Click to expand...

I never reread his edit. Just saw the question I answered.

I stand corrected. Thanks TNT.
 
It actually just started with the vibes. About 2 weeks. I figured it was mud in the bead so I power washed them out and that didn't do it. Ill check out the trackbar today.

Thanks again guys!
 
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