Hello all! Due to some parking lot paving in our apartment complex, I am at a 2 week hold on working on my Jeep and thought this would be a good time to have a discussion on here about one of my next steps. Let me start by saying that I picked up a '99 XJ and recently finished installing a 3" Trail Masters suspension lift. This included new front springs, new leaf packs for the rear, new shocks all around, and a drop for the front sway bar. I just had an alignment done at a reputable off road / 4x4 shop as well. The Jeep drives pretty good I'd say, it's a bit bumpy with the new stiff springs, but it drives straight and the steering doesn't shake at all. The only issue I'm running into is some drivetrain vibration at like 25-35mph and above 60mph. It's not bad or violent, but it is audible for sure. The shop that did the alignment suggested that the cause is from lifting the Jeep without swapping out the slip yoke for the rear drive shaft. I've heard arguments on the forum that a 3" lift doesn't need a SYE kit, and I've also heard arguments that it DOES need a SYE. In any case, at this point I'm thinking eliminating the slip yoke would be a good idea. One of the additional points the shop made was that with the slip yoke, if you are wheeling and the drive shaft breaks and slips out, you lose all your fluid in the xfer case and can't even limp home in FWD. I figure this is sufficient advice to go for it.

I've only read up a little bit on SYE kits, but I am posting here to hopefully get some more information. From what I've seen, it sounds like something I can do at home in my garage. I was hoping to get advice for how to choose a SYE kit and wanted to ask if I need to get a new driveshaft as well? I've heard some people saying I need to get a new driveshaft with CV joints instead of the slip yoke. I just want to make sure I do this correctly, get all the parts I need, and know as much as possible up front. This way, when the pavers are done with the parking lot, I can get the Jeep back in the garage and get this vibration knocked out. Then I can finally get a good set of 31" tires!

Thanks in advance!

 

Yes, you need a new shaft. The yoke end will be completely different, hence the name slip yoke eliminator. There are two types of kits, Hack and tap type that is cheaper where you cut off part of the tail shaft, drill a hole in the center and tap new threads for a bolt to hold on the new yoke. The others all give you a new shaft and or housing. Up to you on how much you want to spend or how strong you want it to be. At the top of the heap is the Advance Adapters/Tom Woods kit that is pretty much bullet proof

 

I don't want to hack and slash, I've been trying to do everything correctly on this car. But in the same vein, I'm not professionally rock crawling every day. This car will see sand dunes 3-4 times a year and maybe some random off-road trails here and there. Otherwise, mostly street use. I'm ok spending money to do it the right way. Can you link me to some kits?

 

After i lifted my 99 using a RE 3.5 inch kit, I had similar vibration issues. I bought an advanced adapter/tom woods combo through rusty's. It worked great. You may also need to shim your leaf springs. I shimmed mine 4 degrees.

I had a shop install my SYE. I was not comfortable with tackling it myself.

 

Did your 3" lift kit come with spacer blocks to drop the transmission crossmember? You would probably solve your vibrations with a 1" drop. Not as good as a SYE but for smaller lifts solves most vibration issues. Worked for me when I did my IRO 3.5" lift.

 

a transfer case drop is a bandaids. It does harm to other components. This guy is already willing to do it the right way. Let's just help him with that and not put him backwards haha

 

Correct. The kit does not drop the transfer case, and I would prefer to stay away from that. A brief google search tells me I'll be spending like $400 to $500 on this. Does that sound right?

 

sounds about right.

 

first off, what transfer case are you dealing with here ? it affects the sye issue & the cost of it.

 

I think it should be the NP231 since it's a '99 XJ, right?

Also, I spoke to the wife about this last night. Since this is a joint project car (at least financially), she is hesitant about starting this work. Not mostly due to cost, but because the cold weather is coming and we are planning to move after the new year. And the last thing we need is a non-movable car when we start moving everything. Plus time to work on the Jeep may be limited. What I wanted to ask you guys is: do you think there is any safety issue to worry about by not fixing this vibration issue? We will mostly be driving it to and from the store or work, mostly around town until at least next year.

 

it could have the 242 tc, does it have a fulltime mode on the tc shifter bezel ? if not its a 231,

 

No full time, just part time

 

Doing the SYE is a good idea at any lift above stock really as it helps to strengthen your drive-train. I did my SYE over a weekend with mostly hand tools. It can be done by anyone that has enough sense to install a lift kit.

I bought my SYE and Drive shaft off of Amazon.

http://amzn.to/2xMqqKw

http://amzn.to/2kXvA5i

I was impressed with the build quality of both pieces and had ZERO issues.

 

You can do a hack and tap sye and use a front driveshaft for around 200.

 

Thanks guys. I would prefer not to hack anything together on this car. I'd rather do it the right way. I can wait on this assuming there are no serious safety concerns. There are some other areas I would like to work on like updating the cooling system, seafoam treatment, fixing the holes in the floorboards and maybe fix the window switch. This SYE kit may wait a bit. But thanks for all the input!