XJ 4.5 inch lift I have an issue

Chad19

Active Member
Joined
Feb 24, 2015
Location
Climax nc
Installed a 4.5 lift, new coils, lower arms, shocks, etc, and new rear leafs and shocks. Put the transfer drop shims in to reduce pitch. Now all is done looks good BUT now I have terrible vibration almost like grinding noise. Starts at about 10-20 mph. Levels out now and then. Do you think it needs a SYE and new rear shaft? If so what about the front? Any thoughts or input would be appreciative.
 
check the driveshaft ujoints. also the pinion and tcase angles
 
U joints seam to be fine. How much play should there be on the yoke that comes out of front differential? When I rotate it moves 1/2" or more before it grabs. Didn't have a problem till I lifted it. So it has to be something with drive line.
 
Pull the front shaft and drive it to see if the front driveline is the culprit. I would say with 4.5" of lift and no SYE, you are beyond the scope of the stock driveshaft's capability. Shimming the tcase down is also making the front driveshaft very unhappy. I would bet that the front CV is approaching the max angle at ride height (unless you did some clearancing to it) and the rear is less than ideal.

I think that 1/2" of play is just slop in the diff if it's open. Probably not an issue but pulling the cover to look for damage wouldn't hurt anything.
 
Okay will check today. If that's the problem. Would an SYE fix the problem or should it? And If I get the SYE do I need new rear shaft as well or will stock still work? Seen or read many different takes on this subject. Thanks for your input.
 
A SYE will solve pretty much all of those issues. I had an XJ with about 5" of lift and could tool it down the freeway without any issues. The shims create more problems than they solve and at that lift, the stock shaft simply cannot be run without vibrations.

You can run an off the shelf CV shaft for your application which is a bolt in affair once you get the SYE installed. You could go to a junkyard and source a new front shaft which has a CV in it already, then find a driveshaft shop to lengthen/balance it. That will require more leg work but may save you a few dollars.

Your best bet is to just buy the SYE with a shaft already and have it arrive in a box on your doorstep if you can afford it.

Also, not sure what year XJ you have. Somewhere in 2000 they started to use low pinion Dana 30 front axles which isn't helping you either. The high pinion models from earlier years really help out with front driveline angles. Just another thing to keep in mind.
 
Its a 94 with 4.0 auto. I will most likely buy a SYE don't have time to do all the leg work. Will I still need a new front front shaft as well
 
Tough to say...IMO doubtful

You should be good for the front shaft and driveline angle at that height with a HP D30. That is from my personal experience with my own 96' XJ. Of course if you are running long arms with tons of droop, may be a different story. I was able to get an acceptable amount of front caster and be able to point the pinion yoke right at the tcase. Zero vibe issues. Just make sure you have good ujoints and that none of the weights have fallen off.

I would just buy the kit and get rid of that tcase drop. If you are installing the kit yourself, I would also look into a new chain if you have a lot of miles on it, replace the shifter fork plastic tips, and change out all of the seals. Cheap money and easy way to head off any potential failures down the road while you are in there.
 
No problem
 
just food for thought for the OP: mine right now is 6.5" with Low Pinion D30 and no vibes, no clicking, no issues even at full droop and stock front shaft and the rear is 2degree shim and grand cherokee rear shaft which is stock longer so i'm just pointing out 4.5" is not an issue at all on lifted XJs..the clicking is either coincidence with the lift or you just didn't notice a bad joint in front axle/or DS until you installed lift. I took mine out yesterday and revved through the rpms no problem in 4wd with my setup and driveshafts so just pointing out to double check your stuff. (usually if you turn the front Driveshaft with your hand and there is play before engaging..that is almost always axle joints so look at them while turning your front DS and see if any one of them move slightly in that 1/2" play you mentioned. if buying SYE is in your budget, go for it, but if money is tighter...that is not your issue that you are describing.
 
Thanks for the input. The front driveshaft U-joints have no play that I can tell. I'm assuming the axle joints your referring to are the U-Joints behind the wheels? Correct me if I'm wrong please.
I will get an SYE at some point but would like to fix this issue before as I don't see it being the SYE to correct it as well.
 
yeah i'm referring to axle joints not driveshaft so while turning front driveshaft...look at each outer axle shaft (behind wheels) and one of them will be moving while ur turning that DS...
 
whichever side is moving replace that joint or both while your at it for only 40 in parts both sides
 
Ok I took the front shaft out tonight and and took it down the road. There was still a slight vibe coming from the rear shaft and when I lifted of the accelerator I could here a short grind like the knuckles where hitting each other at the transfer output end. Those knuckles are pretty close when I look at them. Could that be where my vibration issues are coming from. Guess what Im asking is will that transfer through the transmission to the front and seem worse? Should I use some wedge shims under leafs to try and correct?
 
i reread your post and the vibes are going to be there with 4.5" lift on XJ PERIOD.. you just have to learn to accept that. Having that said..2degree shims will help a lot..advanced auto sells them nowadays for cheap and should put you pretty close. AND YES you do/should get longer rear driveshaft..Grand Cherokee 99-05 rears work perfect and you can put your transfer case back up to regular..for the front go get a Front Driveshaft off a 94-97 Grand Cherokee V8 (must be v8) they bolt right in and are perfect length for 4.5 to 7" lift on xjs. also make sure your front pinion is pointing right at the T-case...use a yard stick or equvilant to check that straight line if need be. The Grinding noice??? im assuming is the rear pinion yoke since it's pointing parallel without a shim (mine did that until i shimmed it up 2degrees) but coulb be wrong though. those joints do get close to each other with that lift and stock driveshafts so looking into longer ones, shim the rear and yes SYE or Hack N Tap SYE is def a plus in the rear. Keep me posted and will try to help as much as possible over the web.
 
no but now that you mention it...the v8 99-05 Grand Cherokees are around 3/4 to 1" different. i have so many and deal with so many i've lost track but take a tape measure with you. the 94-97 v8 front driveshaft is for sure thing.. the 99-05 4.0 Grands rear shaft for sure thing as far as longer 1.75" i believe..the rest i'm unable to make accurate details but measure urs and look around.
 
to mention again..mine with LP D30, 8.25 6.5" lift on 35s, WJ driveshaft rear and stock xj front driveshaft, 2degree shim rear with 1.25 Transfer case drop and at 60mph saturday to trail and back (long arms too) it rode amazing for a xj minus loud ass tires lol
 
and my joints clear no problem at full droop too as i test that out on my ramp at home..picture for that lol
00 xj flex new lift.jpg
 
I have a 4.5 lift on my 99xj, no vibrations. I did have them when I brought it though.
Fixed
Thrust angle of the rear axle.
adjustable upper control arms in front to correct the caster.
1" tc drop to straighten out the rear.

Already has the sye.

The biggest fix on the vibrations was getting the front pinion angle correct. And after you do that, line the toe..
 
John Fuller said:
no vibes, no clicking, no issues even at full droop and stock front shaft and the rear is 2degree shim and grand cherokee rear shaft which is stock longer so i'm just pointing out 4.5" is not an issue at all on lifted XJs.no problem in 4wd with my setup and driveshafts so just pointing out to double check your stuff.
Click to expand...

John Fuller said:
vibes are going to be there with 4.5" lift on XJ PERIOD.. you just have to learn to accept that. Having that said..2degree shims will help a lot..advanced auto sells them nowadays for cheap and should put you pretty close.
Click to expand...

I'm sorry but I will have to gracefully agree to disagree. Both your posts are contradicting in both your personal vehicle and advice to this guy. I would also recommend staying away from shims and if you absolutely need them, to NOT buy any from an auto parts store. They are typically made of aluminum and junk, just like over the counter lift blocks.

With 6.5" of lift on an XJ with a low pinion front axle, you do not have it pointing directly at the tcase because you would practically have negative caster at that point. The geometry just does not exist unless you are cutting the knuckles and rotating.

I will still stand by the recommendation to remove the tcase drop parts, install an SYE, get a proper CV rear shaft, and eliminate all the band aids that cause these issues.
 
Skinny said:
With 6.5" of lift on an XJ with a low pinion front axle, you do not have it pointing directly at the tcase because you would practically have negative caster at that point. The geometry just does not exist unless you are cutting the knuckles and rotating.
Click to expand...
yes ur right i didn't word that right. on mine no its not pointing at it but with his being a HP on 4.5" it should be close to it. mine's way off, lol, but i thought i was being clear to refer to his direction of angles and such. as far as shims go, never seen any issues with the store bought blocks or shims in my long years of using them but i do agree they aren't meant for heavy duty use or abuse which didn't sound like he was doing with it.
 
Well. Put shims in back, adjustable upper arms on front and its on the right track. Just a few vibes not bad. Got a drop pitman arm and adjustable track coming tomorrow. That should help with some of the steering issues I have now. Will keep posted as to how it turns out. Its getting there though.
 
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