hey guys! I'm a long time reader and first time poster so i apologize if this has already been answered.
i put a 4.5 RC lift and the 1 inch TC drop on my 2000 XJ a little over a year ago. no problems till 5 months ago when my front driveshaft double cardan joint blew out. i have since been without a front driveshaft to prolong this from happening again.
but just the other day i decided to slap the new front driveshaft on. (didn't have time to drive it then) but in the morning when i drove it, it started making a strong vibration above 25 mph. it literally shakes the whole vehicle. (my cd player won't even read the CDs because its so bad.) i could feel it mainly in the front end.
my question is, has anybody had this same problem? if so what did you do to solve it? my front axle is a live and spins full time, no selectable lockout hubs.
thanks in advance!
-4sport4

 

Is the "new" driveline actually new? or was it a used one? I swapped in a used one and it had the same vibration as the centering pin and ball in the double cardon joint was worn out. If you used a JY/used driveline I would recomend picking up another and having it checked/rebuilt to esure the joint is good.

I have had this happen to me twice, I never actually adressed it as I swapped a front axle and know have lock out hubs...

 

Yes it was actually a brand new driveshaft, cost around 275. I would love to swap to lockouts but I just spent a ton of money on my front axle this last winter. I guess I'll be driveshaftless untill I can figure this one out.

 

hmmm hopefully somone can chime in who has fixed it. maybe a T/C drop would help, or the trans mount is worn causing teh angle to be off? just guesses though....

 

What is your pinion angle?

 

im not sure at the moment. it doesnt look to extreme. i will check when i get home, im actually in school right now...i have an angle finder, but how should i use it to get the pinion angle?

 

You can put it on the flat part of the yoke. you should also check your caster angle by measuring on the bottom flat of the inner C.

 

pics might help too.

 

I had some what of the same prob. I have a 4.5 lift also. it took a year to find it and it was dumb. Most xj's have well over 100k on them by now. given the fact that most people don't lube the running gear is a given. When I bought mine it had 75 k on it and a nasty vibe under my feet. I went through the u joints and finally the front pinion bearing. still a vibe. I thought it might be bent so I took a really long look at the drive shaft. The splines on the slip yoke were wore out. almost zero grease on it. I went off to a junk yard and went through dozens of drive lines till i found one that didnt have slop in the middle for $50. replaced the u joints. tossed the t/case drops installed a slip yoke eliminator on the rear problem solved. I cant say but in your case it sounds like several little things is causing a big one. The t/case drops help the rear d line but not the front. It actually adds angle to the top joint of the front d line. add that plus a wore out shaft, lose bolts ,bad joints, no grease, trans mount bolts broke/missing, things begin to suck. just get under jeep and question everything. you'll find it eventually.

 

Ever get this figured out?