Hey guys. I am getting ready to purchase my lift for my 90 XJ. I have decided to go with Rusty's 4.5 inch lift. According to Rubicon express, they claim that jeeps with 242 t case lifted 4.5 inches or taller will have unacceptable "Front" driveline vibrations. I was considering upgrading to the long arm kit in a year which naturally I would also upgrade to a 6 inch lift. With that being said has anyone experienced this with the 242 full time option t case? And if so any remedies? I have a 231 t case that needs to be rebuilt that will eventually get the SYE kit. But not doing that for a while.

 

You may have some vibrations from the front if you run it in full time 4x4 but in 2wd it should be fine. However with that much lift you are going to get vibrations from the rear with either transfer case. I only have a 3" lift on mine and i get some vibrations from the rear, my transmission mount is bad though so I think a new mount will help. With a lift greater than 3" you need a SYE on either case.

 

Usually it's the rear DS that exhibits vibration first because of the slip yoke on the output shaft; the front is already a double-cardan joint with a 2-piece shaft. I did have some slight vibration (more noise than feel) at highway speeds until I got a longer custom front shaft from Tom Wood. I assume it was because of the splines having a shorter mating length due to the lift.

 

Can you explain that?

 

If you have a u-joint going bad or the driveshaft angle is too much then it could cause vibrations in 4x4 when the front driveshaft is being powered. If it gets too bad it will be viberating all of the time since the front shaft is always turning.

 

Okay thanks for the clarification. I thought you were suggesting the front DS didn't turn unless you were in 4WD, but your answer totally makes sense now.

 

i lifted my truck with the Rubicon Express 3.5 super flex kit, ended up with acceleration and deceleration vibes. I ended up putting in Upper adjustable control arms to fix the front angle to get rid of my deceleration vibes. In the back I added an axle degree shim on the rear and did a 3/4" t-case drop which finally ended my acceleration vibes. Drives great at all speeds now.

 

That lift , aside from resulting in less spline engagement at the front driveshaft slip joint, will also increase the angle that all the u-joints see, which usually causes vibes as well (unless you put in new u-joints) due to the u-joints moving in a different cyclic range.

 

Wow thanks guys! I installed a Rough Country 4.5 inch lift. I am very satisfied with it so far, actually I don't have any vibration, I do have some rubbing noises I didn't have before when I turn full lock either way. I suspect the 242 is a little worn out lol. The kit came with a transfer case cross member drop. The front control arms changed the pinion angle just enough to make a difference. So far I am pretty happy! I will be starting a new thread about changing over the ABS unit. That pump runs a lot more now with the 31's 😂