thebe001

Help!!!

I just installed a 3.5" in lift (1.75" OME coils + 1.75" spacer, OME shocks, JKS adjustable track bar and longer lower control arms) on my 99 XJ manual. After the install there was a noticable vibe coming from the front. The vibe gets worse is 4WD High, I have not had an alignment yet but I am almost positive its drive line related. Its is definitely isolated to the front because I have not installed the new leaf pack yet, prerunner style. Will a T-Case drop or new U-Joints help?

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After-

99 Purple XJ

Are you lifting the rear

freegdr

finish lift install the address all issues

ehracing67

Start there. But if you installed longer lower control arms, you've increased the caster of the axle which will decrease the pinion angle thus causing a u-joint vibration. Might want to look into changing out the upper control arms to lessen the caster angle.
The book says a 7 degree of caster for stock, but I'm running iron rock short upper and lowers and using 3 degrees of caster to eliminate the front vibes. This also helped to push the front axle forward enough to straighten out coils.
But finish installing all components first to get near level ride. Good luck, you've got the right jeep!

thebe001

Thanks for the advice gents, I will be be installing the rear lift tomorrow night and if I have time I will get the alignment done hopefully I can get a print out with the current caster for a bast line.

The Lift minus the lower control arms-

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thebe001

I thought the upper control arm length stayed relatively the same for lifts under 4"? What caster angle should I be shooting for?

ehracing67

Keep us posted.

MuscleHead

If the current u joint has been operating at the same angle for thousand of miles a fresh joint could cure your issues. Has for a few people i know of.

1988cherokee

Every vehicle is different some can get away with stock uppers some cant.I'm at 4.5 with just lowers and my front shaft vibrates. I thought it was just the old u joint so I changed the joint and the vibes got better but not completely gone. I suggest adjustable uppers so you can fine tune it. Thats what Im going to have to do

helmut

You probably checked this already. But if not : check for slack in the slip joint on the front driveshaft. Mine is shot and wobbles like crazy. It was always like that but did not become apparent until I lifted the front more. Remove the driveshaft and take it for a spin , that way you know if the wobble is driveshaft/pinion angle related.

thebe001

I just installed the rear lift and got more vibes from the back, cant even notice the ones up front now. I will try a t-case drop as a band-aid until I get a SYE for the back. I think I will try new U-Joint up front as well.



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