My wife and I are leaving California tomorrow for a 16 day Jeep trip through the Grand Canyon, Mesa Verde, and Alpine Loop Area in SW Colorado. I Just finishe the gearing, and new suspension on my 99 XJ. It has Rustys 4.5" springs in front(Actual lift height closer to 5-5.5") with RC drop brackets. New driveshafts all around. I set up the lower arms to equalize wheelbase left to right. I set toe at @ 1/8. My first front diff angle measured on level garage slab, was @ 83*, and I was getting a front vibration at @ 75 MPH. I added some shim packers to try and raise the true caster. At 84.5* the vibes are still there, but a tad worse. Most noticable when I let off of the accelerator. Rear drive shaft is perfect. Any ideas? I know for my lift height, I should aim for 86* front diff angle, but I imagine at this point the vibe would be worse if I did that. Should I just go the other way and try to get less angle? Thanks for your thoughts.

 

Sounds like you got the front end all buttoned up, which is great, but did you check your wheel bearings? what about your tie rod ends? How is your tire wear?

 

I did not replace the wheel bearings, but they are solid. The TRE's are fine. I have no issues with death wobble, just driveline vibes I think. In 2WD, at @ 75 MPH, if I take my foot off of the gas, it vibrates pretty good. I removed the front driveshaft to see how it does on my way home from work. Process of elimination.

 

Ah my apologies from your first post I figured it was a DW problem. Now you said it sits at 5-5.5" right? Your gonna most likely need an SYE, at the minimum a TC drop.

 

Sounds like mine... I put in a sye kit and walla!

 

I have an IRO hack and tap SYE. New CV drive shaft as well and the rear angle is perfect. Has anyone had trouble with a hack and tap yoke vibrating??

 

Like 80% of DL vibes are from this. Rule of thumb is usually anything over 3-3.5" an SYE or TC drop is needed. Anything over 4.5" an an SYE is needed. But not all Jeeps are the same so its just an rough estimate.

 

I actually do not run an SYE. I got lucky with my 4.5" lift. So I can't answer that one. Sorry brotha

 

You all do realize he's talking about front driveline vibes, even though there really shouldn't be any. It has a double cardan driveshaft, exact same setup as a SYE.

 

Pull front shafts, drive, see if vibes go away. Do the same with the back one out driving in 4wd. If they go away, you know what's bad. I if not, it's a wheel bearing or something.

 

Found the problem. Bolt holding rear yoke to TC was almost all the way out. I used red loctite on that thing. Maybe not enough. Now the yoke did not fit the shaft very tightly from the get go, now it fits even worse. I Pulled out TC last night. Installing HD Teraflex SYE tonight. Vacation start time officially postponed by 1 day. At least I caught it before rear yoke came off on highway in the middle of nowhere!

 

Glad to see you got it fixed and thanks for tellin us your problem. That way when people with a similar setup and problem can check there first! Have fun on your trip!