1989 comanche mj Posted April 23, 2016 Share Posted April 23, 2016 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. Link to comment Share on other sites More sharing options...
xjrev10 Posted April 25, 2016 Share Posted April 25, 2016 Take the drop kit out and get yourself a Hack N Tap sye kit and a new rear driveshaft. Or get a actual sye kit for your 231. If you're buying new shafts anyway, might as well do it right. Link to comment Share on other sites More sharing options...
Tykerp Posted April 25, 2016 Share Posted April 25, 2016 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. Link to comment Share on other sites More sharing options...
DirtyComanche Posted April 25, 2016 Share Posted April 25, 2016 If the angles are right it won't vibrate. But unless it's a pavement princess I would be getting a SYE. Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 25, 2016 Share Posted April 25, 2016 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. Link to comment Share on other sites More sharing options...
xjrev10 Posted April 27, 2016 Share Posted April 27, 2016 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... Link to comment Share on other sites More sharing options...
mvusse Posted April 30, 2016 Share Posted April 30, 2016 Take the transfer case drop out. It is not needed for the rear of an MJ, and it makes the front driveshaft angles steeper. Link to comment Share on other sites More sharing options...
Tykerp Posted May 3, 2016 Share Posted May 3, 2016 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 Link to comment Share on other sites More sharing options...
COMJNUT Posted May 4, 2016 Share Posted May 4, 2016 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. Link to comment Share on other sites More sharing options...
1989 comanche mj Posted May 13, 2016 Author Share Posted May 13, 2016 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? Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 13, 2016 Share Posted May 13, 2016 How do you get the operating angle measurement? Difference between pinion plane and driveshaft? Exactly. 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. Link to comment Share on other sites More sharing options...
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