Driveline vibration question

All,

I finished installing a BDS 2.5" lift kit. Everything went well. I still have all my fingers and toes. I have noticed that there is a wee bit of driveline vibration now. Its enough of a vibration that I notice, but nobody else does. Maybe I have a sensitive butt, but this has me worried given that my first Jeep Jamboree is on Friday. There is a 1.5 hr drive to get to the base camp and I am not keen on blowing up a u-joint on the way. BTW, what brand of U-joint do you guys use? Yes, I am bringing extra u-joints with me, but, well, you know...

Karl

 

2.5 inches is not a big lift. I assume you've reused the stock axel? If it is real minor, it could be something as simple as one of the wheels out of proper balance. Did you get new wheels? tires? Anything else new? Did the 2.5" springs come with new shims?

 

does it change w/speed, stay steady, or get worse at others?????

 

Only the springs were changed. I did one spring at a time so the tires are even on the same locations. I did not find any weights on the floor after the dust settled. No shims came with the kit.
The vibration starts at about 10-15mph. Vibration increases with speed, but not too much. I had it up to 65 and there isn't much difference. Changes in vibration can be felt when I step on it and step off. There were no shims in the kit. This was my thought too: the caster might have changed. I had a test in mind that consisted of a test drive with a washer under one end of the spring pad to change the caster, but this does not sound like a very good idea. I think a better idea would be to measure the caster at the axle and tcase to amke sure that they are within tolerance. Do you guys think that one trip would be OK, or should I solve this before I go?

 

Changing with acceleration/decelleration sounds like a u-joint failing. Pretty common - the factory rear driveshaft joints on my CJ-5 failed after about 25k miles. They're easy to replace. I'd take the driveshaft off and inspect under the caps.

 

I had to lower my trans.It was pretty easy I just cut some 1/2" plate and put it between the frame and crossmember.I added 1" took out the vibration!
Dan

 

As cj-dano said, it's probably your rear drive shaft. I ran into the same problem when I put a Skyjacker 2 1/2" lift on my CJ-5. I had a 1 degree shim handy and stuck that between the rear springs and axle then lowered the trans skid plate 1". Smoothest it ever ran. Best thing to do is get an angle finder from Sears, Ace, etc. and measure you rear pinion angle and the transfer case output shaft angle. Your pinion angle should be about 1 degree lower than the transfer case output angle.