Help me fix my 60-70mph rumble/vibration!

[JJacobs]

I think we concur that fixing the angles will fix the vibration, nuff said from me.

 

[Fred85]

I appreciate all the replies, i have 2.5* shims on the way

i know it's hard to say prior to install, but should this be sufficient for 2.5-3" lift???

 

[RCP Phx]

Hack-n-taps dont always work w/ the 97+ models,there still isnt enough bearing support.Never got rid of my vibes until doing a HD SYE kit,still smooth as silk 9yrs later!

 

[kastein]

The guy already has a SYE installed so this post doesn't make sense:

Also, since you have an XJ made after 95 (96 and later MYs were afflicted) your TC output housing/slip yoke design is the "modern" one, you might need an SYE or a TC drop to kill vibes even with a stock suspension height, there was a TSB to address this (only applied to some XJs without UpCountry, applied to a lot more with UpCountry suspension package)

Also, again because there is a SYE installed, it is not normal late model rear driveline issue.

Ther problem is the SYE is installed without shims. With the SYE the pinion has to point at the transfer case therefore shims are needed. Less of an angle correction at such low lift, but needed nonetheless. When stock the output shaft and pinion u joints need to be in phase to cancel eachother out. Vibrations result when they do not.

Sorry about that, completely missed the part where he said he already had an SYE and a double cardan shaft in there. Wish you'd said that instead of just saying "what". I agree that the problem is a bad pinion angle due to the axle still being shimmed for a standard driveshaft while a double cardan shaft has been installed.

As far as whether 2.5 degree shims will help - the only real way to tell is to get an angle finder and measure the angle of the driveshaft itself, then measure the angle of the pinion, find the difference, then calculate the angle required to point the pinion one to two degrees below the driveshaft.