post lift serious vibes

Okay so last night I finished up my RE 4.5" lift. I pulled it out of the garage and the was some serious clunking coming from the rear end. I am pretty sure that it is coming from the driveshaftbased on what I feel and what I hear. I didn't shim or t-case drop yet. I have the t-case drop but from what I read after searching most people don't see much of a difference. What shim should I get? I read that it should be 1* for each inch of lift so should I go 4 or 5? I read that I could just grab a angle finder. But I thought I would see what people have used that helped them. This is a pretty serious vibe. I got about 3 houses up and I knew that there was something pretty serious going wrong. Anyone have any advice?

There are no rules of thumb. You need to measure your angles. The question here is: are you doing a slip yoke eliminator and CV (double cardan) driveshaft or are you trying to stick with the stock driveshaft?

If you are sticking with the stock stuff, you may not be able to rid yourself of the vibes. However, you must match the u-joint angle on the t-case end with the u-joint angle on the axle end, as measured on the u-joint cap (use a socket to extend the cap for a flat surface. The angles will be equal in number, but opposite...so the t-case end may be -10 degrees and the axle end should therefore be 10 degrees. If you measure the axle end and find it to be 6 degrees, then add a four degree shim.

But let's get to the point: do a SYE and CV shaft for a 4.5" lift. Then shim the axle to point directly at the t-case (zero degree u-joint operating angle on the axle end). This is the long-term solution, both for case strength and vibrations.

Nay

If you really do have a clunking noise, there is a good possibility that the ears on the rear output yoke of the transfercase are connecting with ears on the front of the driveshaft. If this is the case, you have exceeded the operating angle of the yoke/u-joint set. I had this same problem with my RE 3.5". To remedy this for a quick fix, I took an angle grinder and did some "clearancing" where I could see that it was "self-clearancing." This made it bearable until I could do the SYE and get the rear shimmed.

As far as shims go, mine were 2 degrees on the 3.5" lift, so depending on how yours is sitting, I could see it being 3 or 4 degrees.

Good Luck!

Vibes or Clunking, or both?

While I'm not a huge fan of a Tcase drop, I've never heard of one not helping with driveline angle related vibes....

How about a little more info?What year?AAL or full packs?Ext. shackle?Manual or Auto?

I have 10 inches of lift on my XJ. I didn't have any clunking noises with the stock shaft, I have upgraded since. Go with a SYE (the one with the beefier output shaft if possible vs the hack n tap type). You will have to get a new rear shaft made. This will solve your issues and make the transfer case stronger. The shims may cause some issues with axel wrap and/or breaking your center pins - if you have not experienced that - IT SUCKS!

Chris

RCP Phx said:

How about a little more info?What year?AAL or full packs?Ext. shackle?Manual or Auto?

Click to expand...

93, full packs, 3.5 pack with shackle. Auto 231 tcase

If you've got the t-case drop, put it in. It doesn't take long and will be at least a temporary fix. I ran one for over a year until I could afford the SYE.

i have the full spring pack 4.5" rubicon i used 4* of shim and a SYE and no vibes