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Driveshaft Angle After SYE

M4Madness

NAXJA Forum User
I thought that this was odd, but my driveshaft is the exact same angle after the SYE install as it was before -- 19 degrees. Shouldn't this angle be 15* or less, or is that just for stock driveshafts? I went with the Advanced Adapters HD SYE and double cardan driveshaft from Tom Wood. I didn't install axle shims due to time constraints, and am now wondering if I should go with a larger shim than the 6* ones that Tom sent with the kit when I do install them.

My pinion angle is 9*, so it sounds like 6* degree shims would only yield a total pinion angle of 15*. I also understand that if my driveshaft is 19* that my pinion should be 17* to account for axle wrap under acceleration. It sounds like I may need 8* shims instead, but my question is: when you shim up the rear pinion, does the driveshaft angle also decrease somewhat as the pinion is raised? I mean, if I use the 6* shims, is it possible that it may raise the rear of my driveshaft up slightly to where it might be in the 17* range or so? Or would it remain the same 19* that it is now regardless of the pinion angle?

If I have to run the pinion at 18*, will it have oiling problems? It's an 8.25" in a '96 XJ.
 
Good questions,,,,

With 19 degrees on your DS, I am going to assume you have ~6" of lift. (Mine is 6" with a DS slope of 19 degrees)

Are you using stock shackles on the leafs? I have 1.5" lift shackles which put my pinion at about 11 degrees. 9 degrees does sound like stock shackles to me.

Yes, as you move the pinion up, the DS slope will decrease slightly.

I would not recommend running more than a 6 degree shim. Shock mounts will be out of whack, and that much shimming isn't exactly safe. Ideally, you would cut and reweld the perches.

Go with a 6 degree shim. That should net you a 15 degree pinion angle and around 17 or 18 degrees slope on the driveshaft.

You want to set it about 1 or 2 degrees below anyways to allow for axle wrap on acceleration.

6 degrees sounds perfect for you.

As for oiling, yes, it is a concern. Most people just fill it up extra to compensate. Park downhill, or use a fluid pump, pump extra in and really quickly replace the fill plug.


Let me know if you have any other questions.
 
As you point your pinion up, your DS angle does in fact decrease. I cant say exactly how much, but it will be less than it is now.
 
Thanks for the replies, guys. It sounds like the 6* shims will be enough. It's a RE 3.5" lift kit, but netted 5" of lift. Another consideration is that this lift kit hasn't been on my Jeep two weeks yet. I'm sure that the leaf springs will settle some, and I assume that this will drop the driveshaft angle somewhat as well.
 
You get almost 1.5X in "net" change,example: a 4* shim will have a net change of about 6*!
 
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