Front end vibration in 2wd but not in 4wd

[pfcstone777]

I have a lifted 2000 XJ with a RE 3.5'' lift with 35'' KM2s, AA SYE, Tom Woods DS front and rear. Driveline angles are spot on. My problem is I have a vibration starting at about 45mph and it just gets worse as I speed up. When I shift into 4wd, the vibration is gone but when i shift back to 2wd, the vibration is still gone until I take my foot off the gas and then the vibration happens again. The vibration is not in the steering wheel, but mainly under the seat and in the floorboard.

What could cause this?

 

[RCP Phx]

Have you checked your front drivshaft angles?

 

[CaliXJ]

Have you checked all your U joints for play? Unit bearings? Pinion nut? Could also be a bad trans mount.

 

[CharlesS]

I have a lifted 2000 XJ with a RE 3.5'' lift with 35'' KM2s, AA SYE, Tom Woods DS front and rear. Driveline angles are spot on. My problem is I have a vibration starting at about 45mph and it just gets worse as I speed up. When I shift into 4wd, the vibration is gone but when i shift back to 2wd, the vibration is still gone until I take my foot off the gas and then the vibration happens again. The vibration is not in the steering wheel, but mainly under the seat and in the floorboard.

What could cause this?

To narrow down the problem.... I would remove the front driveshaft and see if the vibration is still there or gone....
If the vibration is gone... then one of the U joints in the front ds is going bad....

 

[vt98xj]

Could be the slip part of the Front Driveshaft also, I had one go bad because of wear.

 

[pfcstone777]

Took out the Front DS, the vibration is gone. So does that mean the DS U-joints are bad?

 

[clean4drxj]

could be the splines on the driveshaft or the joints also make sure the CV ball is lubed

 

[CharlesS]

There is one more thing that could cause the vibrations....; an out of balance driveshaft.
Since you have Tom Woods driveshafts; Tom is a really nice guy so I would contact him to see what he can do for you....