93gc40

Here are the angles of my rear driveline, TC 5deg down, Shaft 13deg, rear end 11deg up. Currently have 1" TC drop, 8.25 rear end, 3.5" of lift (1.5" shackles and 1.5" B-pack). I do have very slight vibes. What would be best to get correct angles, can't afford SYE at this point. And this may apply there as well. Should I use a 4 deg shim with the Drop or 6deg shim and remove the drop?

xjbones

want your t case and pinion as close to parallel as poss. i would personally deal with the vibes until you can afford a sye. alot of the time shims enhance the vibration

4.3L XJ

Drop your pinion 6 degrees and you will have it. If it is too much for the slip yoke, substitute the YJ slip yoke and you will be good to go

That Jeep Guy XJMJ

at 3.5" you do not need an SYE at all.... thats only considerable at 4.5" or more, i think you getting over worked about little vibes.... its a jeep, and its lifted..... Its not gonna drive like a stock jeep would.... if your that concerned about it then try whatever you think would work and if it doesn't then try something else.. your better off that way cuz then you have the experience

okcjeeper

Holy cow telling someone they don't need an SYE till they hit 4.5" or more lift is insane and stupid. If you have driveline vibes whether it's 1",2", 3" or more you need 1 of two things, either and SYE or T-Case drop. Also if your pinion angle is off then yes you need shims to get the pinion angle back in line but that is not the cure all for drive line vibes. Bottoms line to have a proper driveline you need an SYE/t-case drop to get the DS binding taken care of and you need to make sure you pinion angles are correct. You do not have to just deal with the vibes and no vibes is not just because it's a jeep it's because of bad driveline angles post install of a lift.

Now to the original poster. Yes get some shims which will bring the angle in line with how they should be for the pinion and that will help with vibes but may not cure them. If a t-case drop and proper pinion angle does not fix the vibes then you need to save up for an SYE.

xjbones

dont really think its insane or stupid...every jeep is different when its lifted.

he has a tcase drop..cant afford a sye.....should prob deal with vibes.........

i have owned and built 16 xjs all with different suspension combos. some needed sye some didnt....had one with 5.5'' of lift, no tcase drop, no shims, and no sye with no vibes at all.......like i said, NOT INSANE OR STUPID

4.3L XJ

I am going to disagree on this. It is common in this forum to just start throwing tcase drops and shims on the axles at this problem. The real problem is that his tcase and pinion angles are not in alignment. There is a six degree difference. This is too much. They need to be less than five degrees apart. Better yet within two degrees . If they are they will not vibrate on any vehicle. Six States distributing, a driveline manufacturer will back me on this. Some lift manufacturers like Rough Country for instance include shims already bolted to the spring to tip the pinion up. Or others I have noticed will arch the spring in such a way that it tips the pinion up. And others just provide a regular spring and no shims. That is why XJs seem to vary so much. In his case, there is probably already a shim that he just needs to remove. If the angles are right, you can run a 4.5" lift without vibration. Above that it is still possible with a YJ yoke.

93gc40

I agree. so what would be the best way to correct, short of SYE. Remove the TC drop and use a 6 deg shim or add a 4 deg shim with the drop?

Lift is bastard pack, no shims. I may go ahead and pickup a YJ yoke, now. Need to pull the boot to see how extended I am now. I will do a SYE later, planng to lift to 5". Doesn't make sence to do the SYE and DS now, as the shaft will need to be replaced when I lift the rig.

4.3L XJ

If I am reading your numbers correctly, the pinion is high. Is there an extended shackle on the springs? Again if I am reading your numbers correctly, the four degree shim should be put in backwards to lower the pinion. That with the YJ yoke should allow you to get down the road OK. All of your numbers are related to level right?

93gc40

Yeah numbers are to level. yes lift is 3.5" (1.5" shackle with a Bastard pack) have TC drop in 1" nets about 2 deg down from stock. Options as I see it is keep the drop shim axel 4 deg = axel 2 deg below TC. Remove TC drop and use 6 deg shim = same resulting angles, but without the rest of the drive train twisted in the mounts.

SYE and TC drops don't seem like correct fix for pinion angle to me. It is the axel that was rotated by the lift not the drive train. Longer yoke and fixing pinion at the axels does seem correct. If the Vibes go away great if not then a CV drive shaft makes sense.

4.3L XJ

I am going to make a suggestion here. Ditch the shackles. That is what tipped up the pinion. Also these things are hard on springs. Go to the wrecking yard and get some rear springs off an 80s or 90s S10 or other GM equivalent. Use the XJ main leaf and the bottom three leaves and this will get you about 4" and a good ride and return your pinion angle to what it should be.

93gc40

It's nice to finally have a reasoned conversation on this subject. Without the automatic, "You Gotta have a SYE". SYE is a good fix, but in some cases is a bandaid, as is a TC drop. I just think if you change the pinion angle, at the axel, you should fix it at the axel. If you still need to do more to fix vibes or DS length/travel issues then start looking at SYE and TC drops.

While I agree, the shackle is what cuased the pinion to be tipped up. Going back to the stock shackle does not seem to be a better solution than adding a shim. The stock shackle will greatly reduce flex and be almost verticle, if not pointed to the front. Maybe I could go to a boomerange type shackle. I may get some S10 or Dakota springs, soon. Waiting for cooler weather, don't want to go to the JY in 105 heat. The bastard pack I have now is just wrong, and very stiff. I do have a longer yoke, but need a little more lift to install it.

The lift I have, was installed by the PO. It was 5.5" when I bought it, I puller the block and spacers, the day I got it home. It is still on stock front arms and trackbar. I am slowly correcting errors and picking up parts to lift it the right-way. Goal is 4.5-5".

Mike1998XJ

How about an update?
Mike