tcase drop or shims

I have a 98 xj with a 242 t-case, 3" rough country lift and 31x10.50 15" BFG ATs. After lifting I like everybody else had vibe issues. Not having alot of cash left I went with a tcase drop. one of the local 4WD shops sold me a 2" skyjacker drop. After installing it the vibes went away but now I'm getting a mild chain or bearing noise coming from the T-case. I was wondering if I should have used shims instead or less t-case drop. ANY HELP WOULD BE GREATLY APPRECIATED.

2" seems like alot to me. Try a 1" TC drop and see what happens. Twenty bucks from Rustys. Wouldn't hurt to try it. If not, stack up some washers and measure them at the point at which the noise goes away, but I would not suggest to keep the washers/shims as a perminate solution.

Is your linkage also dropped? If its out of position or adjustment, it could be slightly in between 2 and 4, or does only do it in 4hi/lo or just 2wd?

Im no expert, but thats what I would start off doing.

2" is a large drop man, the most I've seen people go with is 1". I'm not sure if the people at the offroad place were smoking something or what but yeah I'd shoot back to a 1" I bet it will fix your problems.

My linkage isn't dropped. Also if I go with a 1" drop will I need to shim the rear ?

I would go with a 1" drop first. Then drive and look at your pinion angle and see if you need to shim. A 2" TC drop seems way too much, actually it's the first time I have ever heard of anyone doing a 2" before.

Remember also that with a t-case drop your front driveshaft actually goes up. At 2" I imagine your front driveshaft isn't too happy. With only 3" of lift you should be fine with a 1" drop.

jeepguy97 said:

Remember also that with a t-case drop your front driveshaft actually goes up. At 2" I imagine your front driveshaft isn't too happy. With only 3" of lift you should be fine with a 1" drop.

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there are two things I've never heard of here one a 2" T-case drop and I'm still trying to figure if you drop the entire case how does the front go up..please explain..I know every XJ is different I'm running 1" drop and 4 degree shims with no vibes and alittle over 5" of lift. also have a 242

XJ1998JEEP said:

I have a 98 xj with a 242 t-case, 3" rough country lift and 31x10.50 15" BFG ATs. After lifting I like everybody else had vibe issues. Not having alot of cash left I went with a tcase drop. one of the local 4WD shops sold me a 2" skyjacker drop. After installing it the vibes went away but now I'm getting a mild chain or bearing noise coming from the T-case. I was wondering if I should have used shims instead or less t-case drop. ANY HELP WOULD BE GREATLY APPRECIATED.

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I have the largest t-case drop I have ever seen on my '99, and it's the Skyjacker 1 1/4" one. I definatly wouldn't go to 2". Have you measured to see if its really 2"? Here is the best plan for you...

1) Remove the drop and check the angles. The pinion to driveshaft angle should be the same as the driveshaft to TC output shaft. If the angle here is off, you might be able to fix it with shims and no drop.

2) If you still have vibs, install a normal sized TC drop of around 1". You can use washers or something to make it for testing, but do it right when you figure out what you need. You might even be able to figure out a smaller drop amount that eliminates the vibs and make your own. Remeasure the angles and shim if necessary to get them within 1 degree. Drive it and verify its right.

On mine I have the 1.25" drop and no shims at all, and its less that 1 degree difference. Thats with an AAL in the back that gave me around 3 1/2" on a '99. With a 2" drop I would have gone over the 1 degree limit and would have had to shim the rear end to match it. I also have a little bit of noise from the TC, but it was there before the lift.

I think I am lucky I have yet to experience driveline vibes. I have the same lift as you XJ1998JEEP. I used to run 30" MT's with it with no vibes, then cut the fenders and threw 32's on.

XJ1998Jeep,

Follow Truk's advice. MEASURE it. You an ask of opinions all day long and it will only be by accident that any of them are correct. Spend $5 on an angle finder and invest a couple hours into measuring everything. Experiment with different drops and shims until you get a feel for what will work the install it and check for vibes. Read Tom Woods article on drive shaft alignment so you will know what you are doing.

There is not a single magic drop or axle shim angle that will work for all XJ's at a given lift. You need to invest some effort to get it right.

John

The Box Said 2" Drop But When Measured Is Only 1.25 In. Also Did You Install The Shift Linkage Bracket ?

XJ1998JEEP said:

The Box Said 2" Drop But When Measured Is Only 1.25 In. Also Did You Install The Shift Linkage Bracket ?

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Nope, left it off. The original bracket looks rusty and I figured if I broke one of the original bolts I'd have a mess. So I left it off and it shifts ok, so I'm leaving it off unless a problem comes up later. I did throw their wierd bolt/stud stuff away and bought new bolts at Home Depot for it.

Any change at one end of the uni angle must be repeated at the other end to keep the angle relationship the same while still running the same driveshaft. My experience has shown that a transfercase drop you are using should be paired with a 2 degree shim to balance the angle change at the transfercase end. With the thin end facing forward it also raises the pinion some, further reducing the angle at both ends and also engages slightly more of the slip yoke spline which is another good thing.

jeepguy97 said:

Remember also that with a t-case drop your front driveshaft actually goes up. At 2" I imagine your front driveshaft isn't too happy. With only 3" of lift you should be fine with a 1" drop.

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X2

1" drop is what i ran with my 3" lift for about a year with no problems

cut that 2"er in half and it should smooth out

sounds like the shifter is off alittle... drive it and put pressure on the shifter in both directions and see if the noise changes.

There is no answer to the drop/shim question except measure the angles, drop and shim till its acceptable.