How many degree's does a T-case drop...

lower the angle on the rear output shaft. I did a really quick job of measuring the angle of the output shaft and the rear pinion, I will double check it and read a lot more so I can fully grasp the concept. The output shaft was 1* and the rear pinion was at 6*.

So how much does say a 1" t-case drop change the angle of the out-put shaft? I'm only running a 2" lift(2.5" in the rear over stock right now) and do not want to spend the money on an SYE and new shaft yet. Thanks!

Do you have vibrations issues that are suddenly there due to the lift? It may not always be the drive shaft angle, it may also be the drive shaft itself since it is spinning at a new angle that the bearings are not worn into.

If you aren't running a double cardan drive shaft then you want to keep the transfer case output shaft and axle pinion as parallel as possible. The transfer case drop will help alleviate some vibrations coming from the higher angle of the upper u-joint. I've rarely seen a lift under 3" that had someone need an SYE but put in a transfer case drop and solved the issue.

SolarBell said:

Do you have vibrations issues that are suddenly there due to the lift? It may not always be the drive shaft angle, it may also be the drive shaft itself since it is spinning at a new angle that the bearings are not worn into.

If you aren't running a double cardan drive shaft then you want to keep the transfer case output shaft and axle pinion as parallel as possible. The transfer case drop will help alleviate some vibrations coming from the higher angle of the upper u-joint. I've rarely seen a lift under 3" that had someone need an SYE but put in a transfer case drop and solved the issue.

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I apologize for the lack of information I provided. I realize you guys must be sick of answering the same questions over and over so I try to keep it brief.

I did get some vibes from the lift, during acceleration, but I am getting some bad noises and vibes at 65mph+. The tires are balanced and the alignment is only slightly toe-ed in too much. On jackstands it looks and sounds like the noises are coming from the T-case and I have a good used T-case to swap in there, but I still have the issues with vibration. I am also going through a U-joint on the pinion side of the rear driveshaft quickly...they only last about 10k. U-joints have both been replace by me.

So I know that the T-case and rear pinion are not running parallel to each other. But is a T-case drop really going to bring the output shaft down to anywhere near the 7* that the rear pinion is operating at?

No. You will get 2 or 3 degrees with a T-case drop. And to do that much, you're going to have to do a huge drop ... to the point that you're being hard on the motor mounts and linkages.

If you are running 6 degree shims and a T-Case drop - you will not be able to get the U-Joints phased correctly.

Get rid of the 6 degree shim, drop the T-Case and try 2 degrees.

If you are only at 2.5'' of lift, you likely won't run the risk of pulling the rear driveshaft off of the slip yoke.

Miller88 said:

No. You will get 2 or 3 degrees with a T-case drop. And to do that much, you're going to have to do a huge drop ... to the point that you're being hard on the motor mounts and linkages.

If you are running 6 degree shims and a T-Case drop - you will not be able to get the U-Joints phased correctly.

Get rid of the 6 degree shim, drop the T-Case and try 2 degrees.

If you are only at 2.5'' of lift, you likely won't run the risk of pulling the rear driveshaft off of the slip yoke.

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I don't have a 6 degree shim for the pinion angle. I have not added any shims or anything to the rear, the lift was achieved by added full leaf packs. I will have to pull the drive shaft to get a degree reading from the actual yoke instead of using the flat spots on the back of the differential.

Ah, in your original post you said it had 6 degrees on it. Wasn't sure if you were referring to the shim or the angle on the u Joint.

What does it look like?

Miller88 said:

Ah, in your original post you said it had 6 degrees on it. Wasn't sure if you were referring to the shim or the angle on the u Joint.

What does it look like?

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Either-way your recommendation of TC drop and 2deg shim are almost right on

Apparently the only way to get good measurements is to measure the actual parts themselves(go figure). Using the flats on the differential and transmission pan will not always give you accurate results. These are my actual angles.

Transfer case out-put shaft: 3.5*
Pinion angle: 5.5*

So yes the recommendation of 2 degree shims and a drop sounds pretty good, I'll have to shim the pinion down. However I will put in a 1/2" T-case drop and go from there depending on the angles. I understand that the pinion actually goes up 1-2* under load or when cruising.

Thanks for the help guys, I'll let you know how it turns out!