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Is a transfer case drop necessary for a MJ with spring over?


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92 mj 4liter 5 speed 4x4 short bed

 

My 92 has a spring over in the rear, RE kit in the front with dropped control arm mounts, and spacers, I guess about 5.5 inch lift.  It has a transfer case drop on it, but I am not sure its necessary, the rear doesn't look like a severe angle to me.  I am planning to get longer drive shafts, the front is wobbly at the slip  joint, and the rear will probably be a bit short with the 8.8 I am putting in there.

 

Will a front shaft from a auto trans truck work?  I used one on my other Comanche but had it cut down a bit.  I am not sure how much longer it is, but its longer.  I have a 2wd shaft I was going to have shortened for the rear.

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I am sprung over and have no transfer case drop or slip yoke eliminator and I get no vibration. I did have lengthen my driveshaft. I am running a chrysler 8.25 right now. My Cherokee has 6 inch skyjacker springs and the longer shackles in the rear and I have neither on it and no vibration.

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92 mj 4liter 5 speed 4x4 short bed

 

My 92 has a spring over in the rear, RE kit in the front with dropped control arm mounts, and spacers, I guess about 5.5 inch lift.  It has a transfer case drop on it, but I am not sure its necessary, the rear doesn't look like a severe angle to me.

 

Not trying to be a smartazz, but it's pretty difficult to tell what your operating angle is by looking at it. Invest in an angle finder tool and measure it. Most u-joint mfg's recommend no more than ~8*, but you can probably get by for awhile up to 12* w/o vibrations.

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I am sprung over and have no transfer case drop or slip yoke eliminator and I get no vibration. I did have lengthen my driveshaft. I am running a chrysler 8.25 right now. My Cherokee has 6 inch skyjacker springs and the longer shackles in the rear and I have neither on it and no vibration.

How much did you have to add? Couldn't have been much. The snout on a 8.25 is 1/2" longer then a 35...

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I am sprung over and have no transfer case drop or slip yoke eliminator and I get no vibration. I did have lengthen my driveshaft. I am running a chrysler 8.25 right now. My Cherokee has 6 inch skyjacker springs and the longer shackles in the rear and I have neither on it and no vibration.

How much did you have to add? Couldn't have been much. The snout on a 8.25 is 1/2" longer then a 35...

 

If I remember right I ended up just doing some research and I found a slip yoke that was slightly longer that fixed it. I could drive it, just seemed pretty far out did not want to push my luck. SYE is in order just wanted to drive it to work out all the bugs after the HO swap

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I drove mine a long time without a SYE or a x-member drop. I got a sye do to wheeling because i didn't want my t-case fluid leaking out if my drive shaft fell out. no vibes at any time.

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  • 2 weeks later...

 

92 mj 4liter 5 speed 4x4 short bed

 

My 92 has a spring over in the rear, RE kit in the front with dropped control arm mounts, and spacers, I guess about 5.5 inch lift.  It has a transfer case drop on it, but I am not sure its necessary, the rear doesn't look like a severe angle to me.

 

Not trying to be a smartazz, but it's pretty difficult to tell what your operating angle is by looking at it. Invest in an angle finder tool and measure it. Most u-joint mfg's recommend no more than ~8*, but you can probably get by for awhile up to 12* w/o vibrations.

 

I have an angle finder, but could tell by looking that its not a severe angle, compared to my TJ, which has a 3 inch lift and no t case drop.  I got adjustable rear control arms and set the pinion and output shaft parallel to each other and it does fine.

 

How do you get the operating angle measurement?  Difference between pinion plane and driveshaft?

 

As far as setting driveshaft length, do I put the yoke halfway into the t case at ride height then measure to get the length?

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How do you get the operating angle measurement?  Difference between pinion plane and driveshaft?

Exactly.  2joint_angle.gif

 

As far as setting driveshaft length, do I put the yoke halfway into the t case at ride height then measure to get the length?

When I did my lift, I had to get a new shaft made. I got the correct length by disconnecting the pinion end of the shaft, inserting the slip yoke into the transmission (or tcase) until the wear mark on the yoke shaft lined up to the seal, then measured the distance at the pinion end I'd need to seat the u-joint cups into the pinion yoke. It turned out to be 1-1/8". I added this distance to the front u-joint-cap-center to the rear u-joint-cap-center distance, and gave this total distance to the shop that made up the new shaft. Then transferred the original slip yoke over to the new shaft.

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