First post!
I've been reading all I can on this great forum since I bought my 1998 a couple of months ago. Got my build sheet from Chrysler, sport package, 4l, auto, with c8.25. The PO put aftermarket wheels and 235/75/15 tires on it.
Some truely great tips from here have been used. I've already replaced the front axle u-joints, the fan clutch since I was seeing some elevated temps in slow traffic in Denver.
My xj had the usual broken down rear leafs so I began reading all I can on budget boosts since I wanted to do a mild lift. This is a DD and used 99% for street/highway miles.
I planned to use the plans here, http://www.rocklizardfabrications.co...dget_boost.htm , for the basis of my rebuild.
I have a set of front coils and spring isolators from a mid 90's GC and when I went looking for some springs to build a bastard pack, found an xj at the JY with a pair of Rancho 1.5" rear leafs.
I bought a new Rancho bushing and u-bolt kit off eBay.
My plan was to first replace the rear leafs, then see what they settled in at, and then adjust the front to match.
I began spraying PB Blaster on all the bolts weeks ago and finally got to it on the 4th. Surprisingly, I only had a lot of trouble with one of the front bolts, but was able to cut it off and drill out the remainder without damaging the threads. Reassembly was pretty straight forward with the only thing I noticed is that it seemed that I had to push the axle forward about 1/2" to get the spring pack bolt to seat in the hole on the axle pad. Also, the rear sway bar did not line up with the link and they were pretty frozen anyway, so for now I have just removed the swaybar altogether, which according to many, is not much needed anyway. I had thought to keep it since I travel from the mountains to Denver a lot for work and flying out of town.
After putting it all back together, I was pleased to see that I had definitely gotten some lift and measured 19 1/4" on the driver's side and 20" on the passenger side. Before it was at 15 1/2" driver's and 16 1/2" passenger. I had thought I would be clever and when I put these used leafs on, I swapped the sides from how they had been installed on the Jeep I pulled them from. interestingly, I still have the same difference in height I had before.
After all that blather, here are my questions:
1-When I took it for a drive, it feels like I have knobby tires. Before it was very smooth and vibration free. I suspect I need to rebuild the rear driveshaft, since my searches show that the u-joints are probably worn out and the lift changes the angle, throwing them out of any wear pattern they had. That is this afternoons project(after taking the dog for a hike)
2-Does anyone have a picture showing correct alignment between the diff and transfer case? Even a drawing would be good. My searches have not turned up much. I read that the diff yoke and transfer case yoke need to be parallel. Does this mean pointing directly in line with each other(---------) or simply parallel, (===).
3-if replacing the driveshaft u-joints does not work, should I try dropping the transfer case crossbar down with washers or ordering some shims for the rear axle. I read conflicting opinions on the use of rear shims with a relatively small lift.
4-assuming I solve the knobby tire syndrome, if the height difference remains, can I just use a different shackle to raise the low side. It appears a GMC shackle might give 3/4" lift.
5-Should I go ahead and install the GC springs or wait till I have fixed the current vibration/knobby tire feelings?
Thanks for any input!

Carl

 

Too long to read.

 

haha.. x2

 

Sorry, I always thought it was better to give more info than less, especially at the beginning of a thread.
Usually my questions are more along the lines of, "want a beer?"

How's this:

I put different leaf springs on my xj and now I have vibration, like there's knobby tires. I also put new U-joints on the rear driveshaft, didn't fix the issue.

What would be the next logical step, shim the axle or try dropping the transfer case?

Thanks,
Carl

 

Thanks man, MUCH better! Were new leafs stock or did you lift. Shouldn't get driveline vibes under 3.5". Also I'm pretty sure you'd only shim if you've got a SYE.. could be wrong, but unless running a CV shaft, you want similar angles at both ends..

 

I did a 3" lift, on the test drive the dome light rattled and had some weirded vibrations , before the it did not. Dropped the transfer case 1", then it stopped.

 

Pulled a set of Rancho 44148 springs at the JY. New poly bushings and u-bolts.
Sitting at 18 3/4" and 19 3/4" now.

Read that the later xj's with C8.25 and auto trans are more susceptible to vibrations.

 

Those leafs are 1.5". Stock height, if measured from stock flare to center of wheel is about 17-17.5" so you've got between 2.25-2.75" of lift. Do you have a 1" shackle as well because the numbers aren't adding up..

Yes, the 97+ are a little more prone to vibes, but at your height there shouldn't be enough lift to cause abnormal vibes.. Don't expect it to drive the same as before the lift, though. You did change the geometry so until you do a TC drop, or better yet a SYE it will be different. Safest thing to do is measure angles at TC and diff. Should be within a couple degrees with the diff angled slightly less.

 

I installed a 2" Old Man Emu lift on my 98' last year and immediately had drive line vibe as well. Had the rear drive shaft rebuilt and balanced, still there. Even though as posted on this thread the lift should be to small to notice vibe. At any rate a Rusty's high clearance cross member fixed the problem. It lowers the t-case 1" without loosing any ground clearance under it. However if you want to run a skid plate for the trans/t-case their unit hangs down an extra 2" below stock. Which is annoying since I just raised the XJ 2" and the factory small skid won't clear the case anymore. I have not yet tried shims.

 

Vibes can show-up with ANY amount of lift in a XJ. The POST 1995 XJs are even more suseptable to driveline vibe do to the design of the slip yoke. This is why MOST lift kits come with or recommend at least a TC drop or SYE.

 

Had to fly out on short notice.
Headed home and hope to address the vibrations.
I understand a SYE is the "best" solution but think it might be a bit much for such a mild lift.
Do I need to drop a full inch or should I try stacking washers and seeing if the vibes go away at some intermediate point. I can pretty easily make up some spacers from flat steel stock once I get the hick ness sorted.

 

I've read that alot. What about a suspension that sags say 1.5" to 2". Ever heard of vibrations caused by that?

 

I don't see any reason you couldn't test out different heights. The angles are so minor that you are not going to be taring anything up in the short run. Just more of an annoyance to do it more than once. Ace Hardware sells steel and aluminum spacers. If I was you I would just go down and buy a pair of 1/2, 3/4 and 1" spacers in stead of dealing with a bunch of washers. I always have projects that the spacers can be re used on again later.