darkstar91

I have a 3 inch lift on my 94 xj and have drive shaft vibrations. i know its the rear shaft because my u-joints exploded on me going down the road. driving home using just front wheel drive i did not have vibrations. I have been told between 3 and 6 degree axle shims should fix it as opposed to a t/c drop to avoid losing that small amount of clearance. what degree shim should install and does anyone know a good place to purchase?

cdawall

did you try new ujoints yet? 17 year old ujoints may not have liked the new angle

Gee oh Dee

x2

At 3" you should not need shims. You should be fine.

Slick761

X3

clayton3854

u joints or tcase drop is where i would start. like said shims should not be needed at only 3" of lift

Gee oh Dee

Tcase drop isn't needed, and really should never be needed.

CherokeeCountry

I trust your knowledge to a great extent, (Not trying to hijack here, just a relevant question.) I'm going to be going about 3.5" on my lift from like 2.75/3 all around, and I'm worried I'll do the lift, then need a T-case drop or have to buy an SYE and install that, which I don't know how to do. You said a t-case drop should never be needed, that meaning I'd just have to do an SYE if I got some vibes?

xjfanatic

The way slip yokes are designed, you cannot use shims. Shims on the axle should only be used if you have a slip yoke eliminator. This is how the axle should be angled with a SYE. The axle would need shims to angle towards the tcase for proper geometry.
This is how it should look without an SYE.

Without an SYE the angles need to be equal. Meaning the only way to reduce the angles is to put on a tcase drop. At a three inch lift, a small tcase drop can be very useful and may be required to reduce vibrations.

someone said earlier, "a tcase drop is never needed", this is true if you want to do the proper modifications to keep ground clearance, but is not always true if you want a smooth riding vehicle that is not necessarily "offroad only".

Hope this helps

Slick761

Don't get toooo crazy, shims can still be necessary without an sye.... if you use shackles to lift your jeep it will twist the pinion up towards the t-case. You can.use shims to fix it.

cdawall

most people need the pinion pointed towards the case. shims are used to fix leaf lifts keep the pinion at its stock angle which is no good as you lift.

Slick761

When you use a slip yoke as in the illustration above the correct pinion angle comes in at the same angle as the output on the transfer case. This is how u joints operate best in this setup... with the sye yes you want to point the pinion yoke at the output to the transfer case

Gee oh Dee

I'll be using a SYE and I'll be using extended shakles as well. No tcase drop. I'm pretty sure I'll be able to get away with using a front drive shaft to replace the rear.

I want my belly clearance.

Slick761

BTW in case you didn't get an answer don't worry about it. Feel it out. I set mine up the way I did on 7.5 with no sye... barely any vibrations to none. Play with it.

Lyon

Someone else posted this recently but had a 2wd Jeep. He put a 3" lift on it an had the stock DS as well and got vibes. I believe what he did was installed the shim the opposite way you normally would with a SYE so he could point the rear pinion down instead of up so the angles were correct again. There is no way we would be able to tell you the exact shim you need. We could be approximate but if it's wrong you'll be doing it again. You really need an angle finder and figure out the shim you need for your specific set up.

I've noticed that the early to mid 90's XJ's can get away more with stock shafts without vibrations. It's odd that at only 3 inches it's that bad. But not all XJ's are the same.

You can absolutely do a TC drop. You will loose about an inch of clearance. I had no problem climbing over stuff with that loss though. I ran one on mine for over a year with my 3 inch and even had it for a short time with the 4.5 inch until I did it correctly and installed the SYE. It's a cheap alternative to help out angles until you can get up the money for the more expensive kit. Let's face it, times are hard and play money is harder to come by sometimes. TC drop approx $25 SYE approx $200. Then you also need a shaft which is more $$$.

Oh and Slick, your PM box is full buddy. I tried to PM you and it wouldn't let my message send to your account.

Slick761

Lol ill clear it.