Eggering

Ok looked around the forum a bit and I know this is a topic that surely has been answered but im not exactly finding what I am looking for. This weekend I installed a 3" Rough Country lift and 31x10.50x15 MT MTZ's. I now have a drive line vibration, surprise haha. I am looking for advice for which brand to go with in regards to a SYE (np231). My next question is whether or not I will need a new driveshaft?, if so what size to go with?, newb still learning. Also, I read up on the t-case drop concept but from my undertanding its more of a bandaid then a solution? Thanks for the help

TheNerd

So far you appear to be on the right track. The SYE is the "right" way to fix the problem. Although I am really against the TC drop option, given your current lift height, I think you could get away with it, but only as a short term option (lets face it: inchitus will set in and you will be looking at how to add another inch here and there...).

So, with the SYE option, it comes down to either a replacement shaft or the Hack 'n Tap. With either option you will need a new driveshaft, but they can differ in design depending on which Hack n' Tap option you go with. I elected for the shaft replacement option (less to screw up, plus you can use an XJ front shaft in the rear, which is nice for replacement/emergency fixes). The x-fer case is really pretty simple to work on, and you can replace the output shaft while the whole thing is in the Jeep. When you get down to looking at SYE brands, there is no real difference.

And since I am already on a roll posting this link today, here it is again (a little driveline vibration education): Enjoy:

http://www.4xshaft.com/driveline101.html

BrofessorXJ

Went with this for my 6.5" LA should be all you need.

http://www.ironrockoffroad.com/Merch...egory_Code=XDT

Eggering

Thanks for the info fellas. Just ordered an SYE (hack and tap) kit and an XJ front driveshaft from IRO. Pretty good prices too! Hopefully I'll have it by Saturday so I install it over the weekend.

chad1978

You may still have to shim the rear axle. I just put on the same lift with a Hack and Tap and a front driveshaft and I still need 4 degree shims. I will add those this weekend and see if it gets rid of the highway vibes im getting.

BrofessorXJ

To OP: I really doubt you will need shims. I'm sitting at 6.5" with just the sye and drive shaft and never needed shims rides great on the highway no vibes at any speeds and i'm talking 80mph+. Just take your time on cutting the tcase spline and make sure you drill straight and pretty dead centered.

Now that I think about it you shouldn't be having vibes at all at 3" and 31's. Really good that you're getting the sye and ds but maybe make sure everything is tight. My trac bar came a little loose and was giving me some nasty vibes.

chad1978

I installed the 4 degree shims this weekend and my Jeep rides perfect now. Just a little update.

4Doors

It surprises me that you've got vibes at just 3", even on a newer XJ. I would double check everything.

BrofessorXJ

x2

Eggering

Well I finally got the SYE hack and tap in from Iron Rock Off Road. Did the install yesterday and everything went surprisingly went smooth. After the install took it for a test drive and the drive line vibe is gone! Wanted to post pics but I left my camera at work. I am very satisfied with the results.