I installed a RE 3.5 Kit on my 89 XJ with a manual 5 speed transmission. I have vibration problems on my rear drive shaft. I replace both ujoints on the rear shaft. The drive shaft vibrates when I accelerate from 20 to 30 mph but no vibrations at hight speeds on the highway. I drove the XJ over 600 miles since installing the RE 3.5 " kit.
I calculated that the angel of the drive shaft changed about 6 degrees because of the installed 3.5" lift. (This is the angle from horizontal at the rear end up to the transmission. The current angle is approximately 18 degrees up from horizontal. The stock angle was about 12 degrees.) I have heard that adding shims to the rear axcle to tilt the axcle up may eleminate the vibrations. I have heard that I should lower the Transfer case crossmember 1" with another kit. Will adding 6 degree shims under the spring pack align the rear drive shaft like it was without the lift?
Has anyone installed RE 3.5" Superflex kit with the new rear leaf springs pack on their XJ? Did you have any problems with front or rear drive shaft vibrations? What did you do to fix your problems?
I also want to get larger tires. What is the largest size tire I can mount on my stock rims? If I want to put 31 x 10.5 tires on the XJ, what width of rims should I purchase? What offset should the rims have? What do you measure on the rim and how do you measure it to make sure you are going to end up with a wheel and tire that fits like a stock rim and the tires don't stick out on the side of the XJ?
This vehicle is my daily driver.
Any help would be appreciated. Thanks.

I calculated that the angel of the drive shaft changed about 6 degrees because of the installed 3.5" lift. (This is the angle from horizontal at the rear end up to the transmission. The current angle is approximately 18 degrees up from horizontal. The stock angle was about 12 degrees.) I have heard that adding shims to the rear axcle to tilt the axcle up may eleminate the vibrations. I have heard that I should lower the Transfer case crossmember 1" with another kit. Will adding 6 degree shims under the spring pack align the rear drive shaft like it was without the lift?
Has anyone installed RE 3.5" Superflex kit with the new rear leaf springs pack on their XJ? Did you have any problems with front or rear drive shaft vibrations? What did you do to fix your problems?
I also want to get larger tires. What is the largest size tire I can mount on my stock rims? If I want to put 31 x 10.5 tires on the XJ, what width of rims should I purchase? What offset should the rims have? What do you measure on the rim and how do you measure it to make sure you are going to end up with a wheel and tire that fits like a stock rim and the tires don't stick out on the side of the XJ?
This vehicle is my daily driver.
Any help would be appreciated. Thanks.



