I just tried to install the hack N tap SYE from IRO and I followed the directions it suggested I cut the output shaft to 1.25" of thread so I did 1.5" to be safe and with the chamfer it's right at 1.25" of thread but when I try to install the yoke it won't go all the way down the threads it's stopping hard 3/4" from bottoming out on the yoke.
The section I cut off the output shaft fits all the way in.
What am I missing here?
Any suggestions?
88 xj NP231
I do have the rear housing and seal.
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The red lines on the back represent how far the yolk will go with the assistance of a large dead blow hammer. The other line represent where the housing sits. Sorry I don't have other photos!

Can you post some pictures?

I added the only photo I have with some context

Is it just me, or is the cut not at exactly a right angle to the shaft? If I'm seeing that correctly though, it doesn't look like a 3/4" offage.

When you measure the back end of the new fixed yoke to the inside (front) face of it and then compare that measurement to what would be represented in the distance of this purple line below, are you sure there's enough shaft to actually fit the yoke on?

I had to modify the yolk to fit as well.
The instructions clearly stated to cut the shaft and leave 1.25" of spline.
That's what you see there is 1.25" of usable spline but the yolk was then a bit too long so I cut a half inch off that as well and it would seat right up to the bottom of the shaft but the splines won't allow the yolk to move any further.
I may need to modify it a little more but I was trying to test fit it so I could sneak up on the amount needed to be removed.
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The housing and seal would still be coving this section.

Yeah, I'm familiar with the hack & tap SYE install procedures. It doesn't seem like you've done anything incorrectly. I wonder if there's a chance that the spline lands on the IRO fixed yoke are actually out of spec/twisted rotationally/cut wrong at the front end of it then?

I’d give IRO a call, sounds like they’re pretty helpful with install questions.

So I got the kit installed today and I'm happy to say it looks geat!
So I'm not sure exactly what the problem was but as stated above the yolk wouldn't go onto the tail shaft no matter what I did!
So I called Iron Rock Off-road and they recommended I run a triangle file over the splines to get rid of any high spots.
Honestly I didn't find a single burr or high spot but I cleaned up the cut area with the file and it didn't change anything. So I put the old driveshaft back in to test fit and it fit perfectly without any hesitation. So I turned my attention to the yolk.
I ran the file on each of the splines and because I had to modify the yolk to fit I also cleaned up the cut area the same as I did on the tail shaft and after a good cleaning to remove any shavings I installed it again but it still didn't slide on so I hammered it down and it went all the way on finally!
It was easier so I must have hit something with the file that needed an adjustment but it was good enough for me so I drilled and tapped the tail shaft, installed the new housing and seal and sent the beauty home for the last time tightening it down with some red lock tight.
My assumption is that the yolk had a couple burrs from manufacturing and considering I've not seen anyone else deal with this issue I'm chalking it up as a fluke. Again the section I cut off of the transfer case fit into the new yolk with ease so I genuinely don't know why this was such a challenge but if anyone else runs into this issue definitely hit everything carefully with a triangle file and don't remove unnecessary material. I sent it home with a dead blow hammer and I'm confident it'll be good to go.


Here are the photos of the finished product! I'm very excited to be done with this "simple" project! 😂
I will be installing the new 8.8 next check out my build page if you're interested in updates!





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Sometimes I think jeeps just wanna hear the frustration in your voice on the second or third try, lol! Glad it worked out!

QUESTION...I'm looking to buy a 1999 Cherokee that is supposed to have a 4.5 inch lit already. I haven't looked it over yet but with this lift, should it have an SYE installed?

Most 4.5" lifts have a transfer case drop bracket to lower the geometry of the driveshaft angles.
A SYE is the better option for clearance but it's more expensive. The Hack N Tap SYE is the least expensive option but I still ordered a custom drive shaft afterwards that was $400 but I also swapped from a Dana 35 to a Ford 8.8.
Basically you should have to do an SYE but you should look into it as an upgrade!