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8* shims with 2" of lift?

Jawa

Jawa

NAXJA Forum User
Location
Aurora, CO
I recently installed a 2" spacer and shackle BB from Rough Country on my 99 (NP231) and now have bad driveline vibes. After spending hours searching through the forums I picked up an angle finder and discovered the following:

Output shaft angle is 5* measured on the flat part of the yoke ears.
Pinion angle is 11* measured from two different places on and around the diff housing and directly on the pinion yoke.
Driveshaft angle is 14*.

I see lots of postings stating that the pinion angle should be 1-2* lower than the output shaft angle. Unless I'm misunderstanding something, I would need an 8* shim to lower the pinion angle down to 3* (2* less than the output shaft).

What I have NOT seen in all my searches is anybody needing anything close to 8* for 2" of lift. Before I go and order shims I'd like to gather some feedback and make sure I'm not way off base here. Any thoughts, suggestions, etc. are appreciated.

Thank you!
 
i don't think they make a shim that big you might want to look into a s.y.e. kit or a transfer case drop those will help with the vibes
 
SYE is in the future for sure, but I'm looking for a quick, inexpensive option to deal with the vibes now. Jeepinoutfitters.com sells an 8* shim from RE. I'm still just blown away by the need for a shim of that size and hoping someone can find an error in my calculations...
 
Check your u-joints.
I did a spacer/shackle BB and bad u-joint showed up with in a day or 2.
Had been bad for a little while but just did not show ANY signs till after the BB.
 
I agree, Check the ujoints. I'm running almost 6.5 inches of lift and I only have a 4* shim installed, no tcase drop. I do have a SYE, but that was to correct the length problems more than anything else.
 
jawa2021 said:
I recently installed a 2" spacer and shackle BB from Rough Country on my 99 (NP231) and now have bad driveline vibes. After spending hours searching through the forums I picked up an angle finder and discovered the following:

Output shaft angle is 5* measured on the flat part of the yoke ears.
Pinion angle is 11* measured from two different places on and around the diff housing and directly on the pinion yoke.
Driveshaft angle is 14*.

I see lots of postings stating that the pinion angle should be 1-2* lower than the output shaft angle. Unless I'm misunderstanding something, I would need an 8* shim to lower the pinion angle down to 3* (2* less than the output shaft).

What I have NOT seen in all my searches is anybody needing anything close to 8* for 2" of lift. Before I go and order shims I'd like to gather some feedback and make sure I'm not way off base here. Any thoughts, suggestions, etc. are appreciated.

Thank you!
Click to expand...

If you are running the stock driveshaft, then you need to set you pinion angle at 5 degrees so that it is parallel to the output shaft of the tcase. Install a 6 degree shim to bring the pinion down from 11* to 5*.

If and when you install a SYE AND constant velocity drive shaft with a double cardan joint at the tcase end, then you want the pinion to point 2* below the tcase output shaft. For that you would need a 2* degree shim to raise the pinion to 13* and match the angle of the DS.
 
Thank you for the responses. I forgot to mention that I replaced the u-joints before installing the BB. I had read on here that they can cause vibes and since mine had over 100k on them, I figured it was time anyway.

Others have posted that with a stock driveshaft the pinion angle needs to be lower than the output shaft angle to account for the pinion raising upwards a little under acceleration. GoJeep talks about it in this thread: http://www.naxja.org/forum/showthread.php?t=915565&highlight=angle+finder+pinion

Does the 1-2* difference only apply with a SYE setup?
 
Rubicon Express also sells steel 8* shims FYI. Steel is prefered since it is not prone to crack under stress like aluminum. The shackle pushed the pinion angle up, you need to point it back down since you have the stock slip yoke.
 
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