2 issues after installing degree shims, please help.

[Atl-Atl]

So I got my new 231 t case in with the sye installed and a front driveshaft in the rear. The shaft is maybe slightly on the short side, Id say it is 60% extended at ride height with RE 3.5" full leaf packs and stock shackles, seems to sit pretty high in the rear. I installed 4 degree shims but I'm still getting a vibe starting at 45-50 and gets really noticeable around 60-65. Should I go up to 6 or 8 degree shims?

Also I got the smaller center pins only to realize when I put them in they were the wrong size. So I need to order new shims with the correct size center pins anyway.

When I bolted it all back together my steering wheel is off about 10-15 degrees to the right! It was perfectly straight before hand, it still drives straight but the wheel is off. I didnt think this was even possible. Could the wheel be off that much because the rear axle was not installed perfectly straight? Could I be getting vibes because the axle is crooked and maybe it doesnt have anything to do with the shim size?

 

[99SJ_Ex]

Go to Menard's or home depot, they sell a magnetic angle finder, use that to determine what you need to do... I had the same prob only I haven't fixed mine yet... gone a year and 2 trips (about 1500 miles) with the vibe... I got used to it...

Also, look for a ZJ with a V-8 in the bone-yard. The front drive-shaft out of that will be longer than the stock front D.S. Thats what I used...

 

[XJ&CHZ4ME]

there is a direct corralation to the steering wheel being off a bit and the rearend being not centered, it will cause the vehicle to "dog walk" and the vehicle will self correct and then while it is doing that the steering wheel will be off. If there really a need to have shims since you have a SYE now? I have ran a SYE in multiple rigs w/o a set of shims and not had any vibes.

 

[Atl-Atl]

there is a direct corralation to the steering wheel being off a bit and the rearend being not centered, it will cause the vehicle to "dog walk" and the vehicle will self correct and then while it is doing that the steering wheel will be off. If there really a need to have shims since you have a SYE now? I have ran a SYE in multiple rigs w/o a set of shims and not had any vibes.

Is it possible that the axle being crooked is causing the vibes, not the pinion angle? I guess anything is possible. I put the shims in because I was under the impression that you need to point the pinion at the t case when you run an SYE. I have no problem pulling the shims out!

 

[99SJ_Ex]

Can only find out if you try... Each Jeep is different. With their Uni-bodies, you can never know until you try..

 

[XJ&CHZ4ME]

could very well be the problem. Having a double cardin shaft in the rear now helps with the angle, so shims may not be necessary now. with your sye you have a longer shaft in there and it actually reduces the drive line angle with the added length instead of the shorter/steaper angle of stock. The shims are used more often without a sye in my experience (weather right or worng :dunno: ). The wrong bolt size can be allowing that rear to wander and get out of align.

 

[Atl-Atl]

I guess I can pull out the shims and put the other center pins back in to see what it accomplishes. It will be a huge PITA if I have vibes still and have to do it a third time to install shims again. Oh well at least its driveable so things could be worse. Thanks guys

 

[99SJ_Ex]

Oh well at least its driveable so things could be worse. Thanks guys

Though it is NOT recommended to drive extended periods with the vibes (can cause wear/damage to trans/transfer case, engine, moter/trans mounts), you can still drive it. If it gets seriously out of control then obviously it needs to be fixed ASAP.

 

[Fore Wheeler]

Output bearings good in t case?

Any slop in the slip shaft?

Pinion bearing good?

U joints good?

Get underneath the Jeep and push up on the shaft, front, center and rear. It shouldn't move at all.

 

[XJ-ARNIE]

IMO, Id check everything out like suggested, but I would most certainly leave those shims in there (after you verify they are the correct ones of course) Also, you said the back end sits alot higher....could be casuing a steering angle index issue....which can lead to problems. Out of curiousity, check the degrees on your front sway bar...it should be around 14*-15*...not on the flat spot before the bolt to the link, but just after it makes its bend out of the bushing on the frame....this could be leading to unwanted vibration.

 

[old_man]

You are correct in your statement that the pinion should be pointing at the output of the tcase. With the change in the front steering, make sure the locating pin in the springs is engaged in the hole in the spring perch on the axle.

The steering wheel centering can easily be fixed by adjusting the drag link, the rod from the pitman arm down to the tie rod. Changing this should not change your alignment enough to register.

Vibes at higher speeds are most always in my experience related to drive shaft balance or having the slip yoke out far enough that it allows the slip joint to not maintain the shaft in a very tightly constrained straight line.

to verify the shaft is the problem, pull it and drive for a few minutes in 4wd. If the vibes go away, you have a shaft problem.

 

[Atl-Atl]

Thanks for all of the supplemental suggestions(fore, arnie and old man) The axles and lift are the same as before I had the SYE in so I am considering them good as I didnt have these vibes before the SYE install. My first plan is to swap around the shafts and see what happens. Im pretty sure its the rear shaft being too extended so Im going to pull the rear and go drive in 4wd to check it. Both slip joints and all 6 u joints seemed good and tight when I installed the shafts. As did all the bearings in the t case when I had it apart.

Something I didnt mention before is the front shaft baaarely fit due to being on the long side I had to really jam it in there and the slip only has about a 1/2" of compression left at ride height. I thought I measured both shafts to be the same length. I may pull them both and compare/reinstall accordingly.

Of course right when this happens the temps drop to 20s for highs and single digits for lows and all I have is a crappy propane heater that only heats the top half of the garage! Oh well could be worse.

 

[FlexdXJ]

You are correct in your statement that the pinion should be pointing at the output of the tcase. With the change in the front steering, make sure the locating pin in the springs is engaged in the hole in the spring perch on the axle.

The steering wheel centering can easily be fixed by adjusting the drag link, the rod from the pitman arm down to the tie rod. Changing this should not change your alignment enough to register.

Vibes at higher speeds are most always in my experience related to drive shaft balance or having the slip yoke out far enough that it allows the slip joint to not maintain the shaft in a very tightly constrained straight line.

to verify the shaft is the problem, pull it and drive for a few minutes in 4wd. If the vibes go away, you have a shaft problem.

The old man got lost again!



Also I know the ideal situation with a cv style shaft is to have the pinion pointing directly at the out put of the t-case as opposed to them being parallel without a CV shaft.

 

[Atl-Atl]

Output bearings good in t case?

Any slop in the slip shaft?

Pinion bearing good?

U joints good?

Get underneath the Jeep and push up on the shaft, front, center and rear. It shouldn't move at all.

Fore Wheeler is the winner . It ended up being play in the slip shaft! The crazy part is, there is no play when you check the shaft out of the vehicle. I checked the slip when i had the shaft out of the XJ butIt wasnt until the shaft was bolted in that I could get the slip joint to move. I pulled the culprit shaft and vibes are gone wOOt! So now I need another stock front shaft, this one will go in the trail spares bin.

As for the crooked steering wheel, I adjusted the drag link to straighten the wheel and all seems well, still no idea how that happened.

Thanks again everyone.

Mike