Lots of posts on SYE and stuff but I haven't found what I'm looking for. We just installed a new RC 3-inch lift on my sons '99 XJ. Everything went together just fine but when we drove it I noticed a vibration right away while on the gas or accelerating. Decelerating there is a strange growl that comes from the back. I pulled the rear driveline thinking I had a bad ujoint now that it was at a different angle and installed new HD ujoints. No such luck, its still doing it. I haven't pulled the front driveline yet because it definatley sounds like its in the rear. I don't want to install a SYE if I don't have to, that is why I stuck with the 3 inch.

Any thoughts?

Thanks!

 

"Everything went together just fine but when we drove it I noticed a vibration right away while on the gas or accelerating. Decelerating there is a strange growl that comes from the back."
Dealt with this myself. Classic symptoms of a slip yoke issue due to the change of rear driveline angle. Remove the rear driveshaft. Put the XJ in four wheel drive and take a spin. GOOD chances the vibration and noise disappears.

 

What's the pinion/driveshaft angle?

 

Seriously? Do it right. Get an SYE kit.

If you don't want to do an SYE, either don't complain about vibrations or don't lift it in the first place.

 

Its not that I don't plan to do it right, My frustration is the reason we went 3-inch and not 4.5-inch like my son wanted was because talking to some guys and researching online, 3-inch would avoid having to deal with the SYE and driveline issues. Did I just have bad luck? A coworker has the same XJ, just installed the same 3-inch lift and he has no driveline issues. I don't have the tools to measure the angles, what is the best way to do that?

 

I use an angle finder from Lowes.
See #25 and #26 in

https://www.cherokeeforum.com/f67/dr...260190/index2/

 

So I'm at 2" in the front and a bit more in the rear. Slight but annoying vibration at 35mph. Clunk/grinding sound when there is slack in the driveline if I let off of or hit the accelerator to quick. Gone without the rear driveshaft. The problem was worse until I shimmed the rear axle and got within ~1.5 degrees of what it should be. Done all that was recommended except to drop the t/c. I learned to drive it where I can keep the problems to a minimum if not at all. I've a sye and driveshaft kit in the garage that I'll install as soon as I'm able.

 

You could try t-case drop spacers as a cheaper option.

 

That's fair. Usually the smaller the lift, the less vibrations you have. On top of that, vibrations happen at certain speeds but not others. No telling if your coworker has shims installed or a transfer case drop.

I agree with the above. An angle finder is the way to go to measure for shims.

 

Definitely try any of the things that may help eliminate the problem(s). I tried the simple least expensive things first. First thing that helped the most was to pack the slip yoke with grease. Had so much in mine that it was all I could do to compress to fit.

 

I needed a SYE, CV drive shaft and angle shims when I went to 3" lift on my 99 XJ.
I never tried a TC drop but if that solves your noise problem, it's worth a try.

 

Did anyone disassemble the driveshaft while it was out? The yokes must line up when re-assembling.

 

^ Good point.
Yep. But marked them for proper reassembly.
I've read many threads/posts on multiple forums when researching how to eliminate slip yoke issues after lifting some XJ's. Like myself some gave up when the issues could not be totally eliminated w/o a sye. I reckon I could live with the bit of vibration I have but not the grinding.

 

so after doing some research and figuring out I have a level app on my iPhone I went out and measured. Here is what I got:

TC: 2 degrees down
DL: 16 degrees down
Rear: 14 degrees up

I found the Spicer driveline calculator and it tells me the first angle is at 14 and the second angle is at 30. I’m way off, aren’t they supposed to be within 3 degrees? I think the factory shim on the RC spring pack is backwards.

 

+/- 3 degrees, but NOT zero (the cross needs to turn in the caps at least a little to prevent uneven wear).