driveline problem caused by leaf springs?

Hey guys I was wondering if you could help with something. I am constantly wearing out my rear u joint every couple of months and continuously hear a bad scraping noise whenever i'm coasting down a hill or let off the gas. Could this possibly be because the driveshaft is too short? I am running the 3.5 RE Superflex kit on my 88XJ with a 1" TC Drop and 2 degree shims. When I changed out the leaf springs I think I might have tightened them completely before putting the tires back on and as a result the springs weren't allowed to settle. My Jeep looks like it is sitting 1/2-1 inches higher in the rear. Could this be why my driveline seems to be messed up because the angle is off?

88XjLaredo said:

Hey guys I was wondering if you could help with something. I am constantly wearing out my rear u joint every couple of months and continuously hear a bad scraping noise whenever i'm coasting down a hill or let off the gas. Could this possibly be because the driveshaft is too short? I am running the 3.5 RE Superflex kit on my 88XJ with a 1" TC Drop and 2 degree shims. When I changed out the leaf springs I think I might have tightened them completely before putting the tires back on and as a result the springs weren't allowed to settle. My Jeep looks like it is sitting 1/2-1 inches higher in the rear. Could this be why my driveline seems to be messed up because the angle is off?

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1. How much engagement do you have on the slip yoke?
2. Which direction are the shims installed? If you don't have SYE you will be installing shims with the fat end pointed forward (ussualy).
3. Loosen up the bolts if you're worried about it not being settled (just half a turn), drive around the block and tighten them back up.

i dont think you need the degree shim in there with the t/case drop. your stock shaft should be long enough for the 3.5" lift. get under there and loosen and re-torque the spring and shackle bolts if you think that might be a problem but that wont kil u-joints by itself. sound like the pinion angle is off. my 90 XJ with 5" lift needs no t/case drop or degree shims. i just used a YJ slip yoke for more clearance.

another question. when you install yhe new u-joints, are you pre-lubing them yourself before install? alot of people miss this step because the joint already has grease in it. but thats assembly lube and certainly not enough. might be heating up because of lack of lube and bad angles.
your pinion and t/case output should be on an "equal plane" and not pointed toward eachother. unles you are using a CV-type shaft but it doesnt sound like you have that mod yet.

Kejtar said:

2. Which direction are the shims installed? If you don't have SYE you will be installing shims with the fat end pointed forward (ussualy).

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think about what you are saying there Kejtar...

and then repost please...

XJ_ranger said:

think about what you are saying there Kejtar...

and then repost please...

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? With a lift in the rear ussually the pinion ends up being pointed upwards a bit. He needs to make the angles equal on the output of the tcase and the pinion so he most likely needs to flatten the pinion down. If he's got no SYE and the shims get installed with the fat end towards the back then he's rotating the pinion even more upwards thus getting the angles all wrong. Granted it's hard to say precisely which direction and how much they need to go, but the general principle is sound.

Kejtar said:

? With a lift in the rear ussually the pinion ends up being pointed upwards a bit. He needs to make the angles equal on the output of the tcase and the pinion so he most likely needs to flatten the pinion down. If he's got no SYE and the shims get installed with the fat end towards the back then he's rotating the pinion even more upwards thus getting the angles all wrong. Granted it's hard to say precisely which direction and how much they need to go, but the general principle is sound.

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right - damnit


at 2:00am fat part forward sounded a lot like this way <


damnit...