my xj rear driveshaft setup

Howdy Y'all.

I was having issues with the rear driveshaft on my XJ and I devised an interesting alternative setup which has worked well for me. It's been on my Jeep for about 6 months now and Ive been really happy with it, so I figured I would share for those who may be intereseted.
So first I will tell you abnout the problems that I was having before this setup.

I am not the hugest fan of the driveshafts used with a SYE. Now stop getting all upset and let me explain. obviously if you are going to lift a TJ more than a little, there is no alternative to the SYE, double cardan joint driveshaft with the splined telescoping section. After all the driveshaft is only 1 foot long. So despite my dislikes (more about this in a second) about this type of rear driveshaft, it is the only option for the rear of a lifted TJ.\

Whats my issue with the SYE/double cardan joint rear driveshaft? Simple: Cost, complexity and ease of repair. A SYE kit is around $300, and the custom rear driveshaft is around$500-$750 more. Now this is a good setup, I'm not dissing it, but within a year or two I started to have problems. With the amount of Maclean mud I've been through, I had problems with the blue coating coming off of the splined section. When this happens, there is no option except for having a driveline shop weld on a new splined section. At this point the female side (yoke) should be replaced too, due to damage caused to the splines by running with the blue coating damaged. I also had problems with the double cardan joint itself. frequent mudbaths and less frequent greasing resulted in a need for maintenance. Although I got pretty fast at changing out the two ujoints and the ball kit which resides within, I still always found it to be a hassle. And before too long there was noticeable wear to the machined surface on the little cylindrical part that contains the little spring and installs into the cv ball. (I'm not sure what this part is called, but it's inside the double cardan joint and the joint will quickly fail if there is damage here). The problem is that the little machined surface, as with the blue coating, cannot be repaired in the garage. If you wear that part, it must be cut off of the driveshaft and have a new part welded on and the shaft rebalanced...$300+ from my experience.
So basically the reasons why I wanted to move away from the double cardan joint on the rear of the Xj was that it is more of a hassle to maintain (3 u-joints, two splined parts, ball kit, and machined stub on a double cardan vs. only two u-joints on a conventional driveshaft) Additionally, the Double cardan shaft has two parts (blue stuff on splines and machined bit) which cannot be replaced by the jeeper, which to me is lame. I like to fix my own Jeep, and I hate giving Pat's driveline money unless there is no alternative.

Of course there are reasons why the double cardan joint is so widely used by wheelers. The main ones I am aware of are that the DC (double cardan) can handle much greater angles, due to it's "splitting the angle" between the two upper u-joints. When considering angle on u-joints there are really two seperate factors, running angle, and maximum angle (almost certainly not the correct terms) By running angle I am referring to what angle a u-jopint will happily purr along the highway at without excessive wear or vibration. By maximum angle I am referring to how far the u-joint can flex before the yoke ears collide. The running angle must be within the allowance of the components or you will get vibrations. This is how it is usually explained, but it would be more accurate to say that too great of a running angle would cause "greater vibrations than normal" or "excessive vibration" since there is always some level of vibration in a driveshaft. So my goal was to find a traditional, 2 u-joint rear driveshaft which would have acceptable levels of vibration, and wher the ears of the yokes would not collide at full droop.

The TJ's stock rear driveshaft is a beatiful thing and rarely gets the rspect it deserves. Obviously it doesn't work with a lift, but consider the flex and articulation that a stock TJ has in the rear, then remind yourself that the driveshaft on an auto trans TJ is less than 12" long and you'll realize it's different than most. To deal with the TJ's increased rear articulation the jeep engineers devised a setup for the TJ rear driveshaft which was very different than what had come before.
The first big difference is the output housing and output shaft on the t-case. Contrary to popular belief, the rear driveshaft on a stock TJ can be removed and you will not lose your tcase fluid. (unlike the XJ and YJ which do not use this design). The TJ's output shaft has it's own seal in the T_case and rather than the output yoke sticking into the tcase and the splines being bathed in atf, The tj's output shaft is completely external and the splines must be greased. The Tj stock setup uses a rubber boot here, to keep dirt off of the splines, the others haver the splined part inside the tcase instead.
The next thing is the output shaft length. I have heard or read several people mocking the TJ engineers for the fact that in such a short vehicle the tcase output shaft was actuall longer than on yj's, leading people to assume that a longer output shaft would equal a shorter driveshaft. Beleive it or not, the longer output shaft actually results in a longer driveshaft as well, and one that is less prone to vibe out. This is because the TJ rear driveshaft components are different than most: The slip yoke is designed to allow the tcase output shaft to go all the way into the yoke, to within a half inch of the upper u-joint. This is how the driveshaft length is increased. Despite the fact that the TJ output shaft is about one inch longer than those that proceded it, it actually allows one inch more driveshaft. And the slip yoke is less prone to vibration because more of it's mass is wrapped around the output shaft rather than hanging off the end of it, flailing about.
Additionally the TJ yokes are beatifully designed for huge maximum angles before the yokes collide, compared to other yokes I have seen on other Jeeps.

So you're probably figuring out where I'm headed...using stock TJ parts on a lifted chrokee.
To do this set up you will need a stock TJ tcase output shaft and output housing, a stock TJ rear driveshaft (these three can usually be had for free) and the rubber boot, slinger, and two metal bands that seal up the slip yoke (i went to the dealer for these). The slinger and the bands are always damaged in removal, and better new when it comes to a rubber boot, I figured.

You will need to open up your tcase, and swap in the TJ output shaft and housing. new seals would be a good idea. Doing this is about the same complexity as doing an SYE.

Then you will need to take the Jeep to a driveline shop, and have them install a longer tube onto the TJ driveshaft components and balance. Keep in mind that thicker walls are stronger against damage but more prone to vibrations than the standard wall thickness. For this reason I had them go 1 step thicker but did not select the tuffest tube they had, as I knew I would probably have issues with vibrations with 4" of lift and a standard driveshaft.

When I did this it worked great. There was some vibration at some speeds, but way less than before with the messed up DC shaft, and way less than what some of my friends considered tolerable on their jeeps. I experimented with rotating the yokes 180 degrees, and dropped the tcase 1/4 inch and the vibes went away.

rcnerd said:

dropped the tcase 1/4 inch

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Right here is part of the reason why people use SYEs (granted 1/4" isn't that much)

You can tuck the whole drivetrain up higher since the double cardan setup can survive a greater angle than a conventional u-joint.

You also need to rotate the pinion up to point 1* degree less than the driveshaft which means your pinion isn't hanging down by the rocks.

There are more benefits to an SYE than just "getting rid of vibes".

I do applaud you for your ingenuity. Nice to see someone looking outside the box! :thumbup:

Thanks...I think I could put the t-case back up and still have no vibes with a little pinion angle adjustment... I'll work on it and report back!

Also I am not claiming that this is in any way "better" than a SYE setup. IT is cheaper and simpler and you can do it (mostly) yourself and that is it's benefit. I think this will work up to around 4" or 4.5" on an xj....although on my local hometown jeepclup website there is a guy who claims to have a ZJ and an XJ both with 8" of lift and the stock driveshaft and no vibes...he seems like a credible dude but I though that was pretty unbelievable...

HastaX 100

ruger81 said:

HastaX 100

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Are you saying that using the TJ driveshaft setup on a XJ is not a new idea? I've never heard of it before. Please explain.
:huh:

People use the YJ slip yoke.

So it's the high clearance type too then? good to know.

With the TJ setup you can remove your rear driveshaft and not lose atf.

rcnerd said:

So it's the high clearance type too then? good to know.

With the TJ setup you can remove your rear driveshaft and not lose atf.

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96+ XJs have the same setup.

so they have the rubber boot like the tj then?
do they have the same high clearance driveshaft yokes?
these would be a little easier to find than tj shafts possibly.

rear ds's are cheap... i use junkyard shafts for 30$ or craigslist shafts for 30$ all the time on 4.5" setup. i agree rebuilding the ball and u joints sucks totally, but an entire shaft for 30$ (maybe another 90$ if it needs lengthened and balanced) . also, AA has syes for 199, PORC has em for 159$. i had a yj yoke put on my junk and the stock shaft retubed and balanced with new u joints for 180. still had vibes even with rear output-1*=pinion angle. did a hnt with a used front shaft (for free) for around 160 total and no vibes. i think 160 is pretty good.... and 180 for a stock setup isnt...

MoparManiac said:

96+ XJs have the same setup.

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x2,buy a good sye kit and call it done.

my sye cost me $170 and my driveshaft $20
smooth like glass at all speeds

and i have tucked my t-case up a couple inches, clocked it and whatnot and still smooth like glass.

if i follow what you are describing (pictures would help) i used to have 5" of lift with the setup you are describing and i somehow managed no real noticable vibes, but when the rear suspension dropped the yoke ears would bind up and make bad noises

Yeah 96+ XJ's use the same Np231's as TJ's (with slight differences in the sun gears from transmission to transmission.) Most XJ guys prefer the older style case with no SYE vs. the newer style with no SYE because the older style is less prone to vibes at lifted angles. But the newer style cases with a H&T SYE and a $30 dollar junk yard front XJ shaft works well too.

Here is the YJ yoke (left) versus XJ yoke (right)



Longer ears allow for much greater articulation without binding

Ya sorry guys I wrote that without thinking most of you are in the US, actually I wrote it thining to post it on my local board so my prices are way out of wack for you guys....we pay about 35% more for off road stuff here even though our dollar is at over 90 cents.
Mine's a manual so I'm pretty sure I can't use those scrapyard front DS as rears without getting it lengthend...which costs a lot here.
We had a pretty good all jeep scrapyard but it recently went out of business and all their jeeps got crushed....very sad to see.
Everything is more expensive here. can you beleive I was charged $350 for a driveline shop to lengthen and rebalance the tj driveshaft? The cheapest place in town i later found out would do it for arond $200 or $250. A far cry from the $90 blondejon is paying in sacremento...and no snow there either...sigh...we do get "free" healthcare but it doesn't apply to vehicles unfortuneately.

This sounds interesting to me. I'm not as elite as the hardcore guys so I actually learned something from this post. Thanks.

talentjeep said:

This sounds interesting to me. I'm not as elite as the hardcore guys so I actually learned something from this post. Thanks.

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That's awesome. In my opinion there is no place where more Jeep knowledge can be found in one place. I'm nowhere near the knowledge level of a lot of the guys on here but it's nice to know someone else found this intereseting.

Thanks to for a great website and user group.

Interesting take on getting rid of vibes. I know some do the SYE for more reasons than just getting rid of unwanted vibrations, I.E. gaining ground clearance. However, I also went about eliminating vibes a different way. I took the stock XJ slip yoke at the T-Case and drilled two holes opposite one another about .5" from the end the splined part, then tapped these holes to accept hex key retaining nubs (what is used on drill stops and the like). I then slid the slip yoke on the output shaft and tightened the nubs (they tighten onto the smooth machined surface at the back of the output shaft and not the splines). This allowed me to run a two joint driveshaft with a slip joint in the middle (the same as the stock front shaft just without the double cardan joint). this effectively lengthend my driveshaft and reduced joint angles. I have had no ill effects and almost no vibes and no abnormal wear on the output shaft due to the nubs pressing on it. Just another take on a rear driveshaft solution.

southernrebel20 said:

Interesting take on getting rid of vibes. I know some do the SYE for more reasons than just getting rid of unwanted vibrations, I.E. gaining ground clearance. However, I also went about eliminating vibes a different way. I took the stock XJ slip yoke at the T-Case and drilled two holes opposite one another about .5" from the end the splined part, then tapped these holes to accept hex key retaining nubs (what is used on drill stops and the like). I then slid the slip yoke on the output shaft and tightened the nubs (they tighten onto the smooth machined surface at the back of the output shaft and not the splines). This allowed me to run a two joint driveshaft with a slip joint in the middle (the same as the stock front shaft just without the double cardan joint). this effectively lengthend my driveshaft and reduced joint angles. I have had no ill effects and almost no vibes and no abnormal wear on the output shaft due to the nubs pressing on it. Just another take on a rear driveshaft solution.

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Wow...it's suprising those two little hex nuts would keep it motionless. Granted, there is not a huge amount of horizontal force acting on it, but spinning at the speeds it does, I would expect issues. How has the maintenence been? Had to tighten those hex nuts up? How long have you been running it?