ProjectXJ00

First post on here, but I have recieved a lot of great knowledge and tips as a reader, figured I would add my own experience. Installed an Iron Rock Hack and tap SYE kit over the last two days on my 2000 XJ with 4.5" Zone lift and 8.25 rear end.
For those who arent familiar with the HNT SYE kits, basically you cut down the TC output shaft to length, drill and tap 3/8 threads, place a 1310 Yoke on the shaft and use a front XJ shaft for a rear driveline. SYE with shaft for under $150.
I know each year XJ will differ and leaf spring differences will make things different also, but here is what I found. If I went by IRO measurments, I wouldnt have any spline left on the shaft to achieve the distance they recommend cutting at. So I threw the IRO specs out the window and found some other users come up with different measurements of their own, and then I cam up with mine....by necessity in the end.

Starting off, I removed the rear drive shaft with slip yoke and got out the meauring tape to find the 33.75 inches IRO specifies would basically leave me with .25 inches of spline left on the shaft, they clearly state a minimum of 1.25" is required, so I measured the front shaft and the distance between yoke and shaft end and came up wiht 32.75" being the ideal length for my setup. I marked the shaft, leaving approx 1.5" of spline and started the cut.

The cut: Using a angle grinder with 4.5" cutoff wheel 1/8" thick, I made sure the TC was in 2wd and started the engine and put it into reverse, this allows the shaft to work like a lathe as it turns and makes the cut straight. BE CAREFUL, the cutoff disc will cut a thick groove if you do not hold the grinder perfectly straight while cutting, by the time my cut was done and I flattened the end perfectly, I only had 1.40" of spline, still OK and within my tolerance for DS length.

Drilling: I (thankfully) bought the optional jig from IRO and glad I did, it slips over the end of the shaft and alows you to check the flushness of your shaft cut and gives a perfectly centered drill hole. Used lots of oil and frequently cleaned shavings out. Drill 1-1/4" deep, first with 1/4" then with 5/16" drill, used Milwaukee bits and they did great, like butter with a hot knife.

Tapping: Used a Century (no Harbor Freight taps) and all went well until the final cut....SNAP......yes I snapped the tap off inside the shaft, my heart sank, the nightmare had begun and a smooth job now turned ominous. I tried welding a nut onto the end of the broken tap, I tried to build up some bead on the end and then work the bead into the nut, it ALMOST worked but I could get enough penetration and wound up welding a nut to my pliers before I gave up, plus I was starting to penetrate onto the shaft and I saw the futility in trying this method, sooooo. I tried to shatter the tap inside the hole but using a sharp punch and smacking the end, I got a few pices out, until the punch broke off inside the tap, more salt in the wound. SO I figured I was doomed, until I thought to trim the shaft down another .15 inches, only cutting until the tap edge and then using the short stub end of the shaft still stuck on the tap to work it out. It worked like a charm, I couldnt believe how well this worked, but one problem, when I measure the remaining spline I only had 1.12" inches left, when I was cutting, the cutoff wheel drifted towards the TC just a tad, enough to put me under spec by .13". What to do?

Outcome: After re-tapping the new hole, I decided to roll with the shorter splines, it seemed close enough and the yoke they provided also needed to be trimmed to seat against the shaft end (it would have needed it regardless as I wound up cutting close to .75 inches off the end) I cut it so the end would rest against the shoulder that flares out on the bottom of the shaft, while still being flush with the end of the shaft cut, it felt really stable, no wobble at all. Installed a stock front DS form a 96 XJ, fit perfect, have about 1.25" of compression travel and almost 2.25" of extension if I want a bigger lift later. No more vibration and butter smooth acceleration.

This kit is worth the money, leave extra spline if you can, you just might need to sacrifice some of it to get a busted tap out. Be careful when cutting, the groove will wind up bigger then the width of the wheel, count on it, be patient and this should be an easy upgrade for even those with modest mechanical skills.

PocketsEmpty

Thanks for reporting your experience! BTW, pictures are a great help!

Flowpro

Great info............thanks. I might be going this route in the distant future.

Dumajones

Good info, I also did the Iron Rock Hack and tap SYE kit on my 2000. Ive had it for a year and a half no probs.. I also had to throw out what they said for measurements.

JeepMN

I haven't read up on the Hack n tap SYE much so I'm a little confused on why you would need a 2nd front driveshaft?

Someone care to explain a little more? Thanks!

FTHESHACK

Pretty much the same experience here with my 01. Been running the hack n tap for just under a year without a single issue.

884x4

It's a double cardan shaft. That's what you replace the rear with if you don't want to buy a aftermarket 2 piece shaft like a Tom woods or something.

XJ Sam

So you are saying you can use the stock XJ front shaft as a double cardan for the rear once the HnT is installed?

How did I not know about this? LOL. I've owned a few XJ's but they all had the NP231. This is my first with the NP242. I've installed HnT's with other guys before, but they always had replacement shafts.

Well....this is going to work well. Wouldn't you know it, I have another 99 front driveshaft sitting at home I was just about to put new U-Joints in, clean up, and keep as a spare. Looks like its going to be put to good use in a couple weeks!

884x4

Exactly man!

Teephphah

Man, I really needed this thread. THANKS!

Timing couldn't have been better.

Atmos

yup. little known fact, the best part about any sort of SYE isn't deleting the slip. it's being able to use the exact same driveline front and rear! only gotta carry one spare




all this H&T business is fine and well. but I have to throw it out there that a full SYE kit is substantially better and only costs slightly more. just get a real one

PocketsEmpty

Costs twice as much in most instances

I'm getting a full SYE when I get the cash....anyone like to donate?

884x4

I would get a full sye if I diddnt have a 242. I don't want to spend 500$ on a sye for my 242

XJ Sam

Great fact to know indeed!

I agree that full SYE is the way to go. But, as I understand it, the HnT is the only option for the 242. Correct?

Hopefully further down the road when this Jeep is no longer a DD for me and I have another vehicle again, it will get a T-Case swap.

ProjectXJ00

Hey, looks like my rig, BTW did you have to move or trim the black plastic O2 sensor mount on yours? The CV was really close to mine, when I punched it, the edge would rub against the mount and sounded like all hell breaking loose under there, so I had to remove the mount and re-route my 02 sensor wiring, just used 3 well positioned plastic wire clamps and self tapping screws to keep it all tucked up against the body over the TC, it eliminated the black plastic mount altogether, and gives the cv room to flex some. Glad to hear yours is solid after a year in.