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Advice for a 242 sye

Jjcord2015

NAXJA Forum User
Location
Illinois
Hi everyone. I'm getting ready to lift my 99 xj 4.0 auto with the np242. I have read all the posts I can ad nauseam. And I'm as confused as ever. If I don't want to tear apart my tc for the tom woods sye, Can i just use the iron rock off-road hack and tap and use a front driveshaft from a 91+ xj with 4.0 and auto? Will this driveshaft not need cut? I was going to order a new front driveshaft from car-parts.com, they're about $139. The hack and tap looks to be about $100 or so. Seems to be a better price than the TW route.

I'm planning on 3-3.5" of lift from ome medium duty rear leaves (rated at 3.5") and the ome v8 zj coils with acos adjustable coil over spacers to even out the front depending on the amount of lift I get from the leaves. Going to run 31" tires. Any help would be appreciated. I'm going to buy everything I need before hand so I only tear into this thing once for the lift/drivetrain.

Btw, this is a daily driver and def not a trail rig. Just looking to improve the looks of the jeep. Thanks.


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The 231 and the 242 are nearly the same length, so yes it is highly likely that a stock front driveshaft will fit nicely. I strongly suggest you read the IRO instructions and then cut the output shaft about 1 inch longer than calculated. You can always check the fit and trim it again.

Unless you plan on additional lift later on, I would skip the V8 springs and the ACOS and just get a set of 3 inch lift coils. If necessary, you use poly coil spacers to even out the front.

At about 3+ inches of lift is when the 97-01 benefit greatly from an SYE.
 
You will probably be fine with just a t case drop. If you even need one

This, just be sure to look at the slip yoke and make sure that there's less than two inches showing. Grab it, push and pull to see how much the yoke deflects. More deflection = less spline engagement. At that lift it shouldn't be an issue unless the yoke binds when you come off of a bump, and there's really only one thing that makes that sound.

I used 1" box tubing and a dollar worth of bolts to drop my case at 4.5 inches of lift.
 
This, just be sure to look at the slip yoke and make sure that there's less than two inches showing. Grab it, push and pull to see how much the yoke deflects. More deflection = less spline engagement. At that lift it shouldn't be an issue unless the yoke binds when you come off of a bump, and there's really only one thing that makes that sound.



I used 1" box tubing and a dollar worth of bolts to drop my case at 4.5 inches of lift.



Ok thanks. I'll check that out.


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I ran the HnT on my 242 for a few years, no problems with it for street and basic trails. The driveshaft length is determined by your transmission (auto is longer than manual) and rear axle (8.25 and D44 have a longer pinion than the D35). You will need to measure the precise length to be sure.
 
I’m running an IRO SYE on my 99 with a 242. I went with a different seal housing. It’s mentioned on the go-Jeep site. Someone he knows makes them. I used a pick-a-part front shaft. I’m at 4.5 inch lift. Works good! Don’t forget you need to shim the axle so the pinion lines up with the shaft. I’m running 8 degrees, but with 3” you likely only need 4 or 6 degrees. IRO has them cheap and in steel. Don’t do aluminum shims.

Happy wrenching,
 
I did the IRO hack-n-Tap on my 01, 242 with 3.5" lift. Used a used front DS with 6* shims (-2* pinion angle from DS straightness for acceleration). I feel much better with that than the TC drop putting stresses on the engine/trans mounts. Plus it looks better without the TC hanging down.
 
I did the IRO hack-n-Tap on my 01, 242 with 3.5" lift. Used a used front DS with 6* shims (-2* pinion angle from DS straightness for acceleration). I feel much better with that than the TC drop putting stresses on the engine/trans mounts. Plus it looks better without the TC hanging down.

I would have paid more for the slip yoke modification than I did for the whole truck, so I settled for spacers on the cross member rather than let it sit until it became practical. On that note, I also made my own coil spacers and built the leaves from stock extras. Overall, my 4.5 inch lift cost less than $35 with U bolts and spring hardware. Also, I tapered the box tubing to provide a ramp at both ends, allowing better passage over rocks, and improving the aesthetic over washers or whatever other people use in a pinch. Next time, I'll use 1x2 box.

I immediately put it overland for a 1750 mile road trip, 300 miles of dirt, and probably around twenty miles of rough trails and rock gardens. It did chew up a factory motor mount, but I also flogged it relentlessly across some rough country. New mounts are about $20.

Mall crawler? Why bother?
 
Tom Woods no longer has the exclusive right to sell the Advance Adapters 242 SYE. They are speedy wherever you buy them though. When dropping the transfer case, there is extra strain on the motor mounts, the shift linkage needs to be adjusted, and the exhaust is forced down lower too. I would look to either the SYE or the hack and tap rather than a TC drop.
 
I run the IRO hack n' tap in my '99 with a 242. Installation was really simple and it works great. I'd definitely go that route over a much pricier SYE or a TC drop, for reasons mentioned by Greenz.
 
I run the IRO hack n' tap in my '99 with a 242. Installation was really simple and it works great. I'd definitely go that route over a much pricier SYE or a TC drop, for reasons mentioned by Greenz.



Nimrod what did you do for driveshaft?


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I was on the same boat as you recently. This is my first Jeep so I had to learn a lot. I wanted to lift my 98 XJ to fit larger tires, but is was a daily driver also that won't see a trail. I've got atvs and utvs for that. Went with a 2 inch lift and new replacement springs in the rear which took it higher than 2". Had a vibration from the rear shaft from 20-40 mph. Was ready to do the H&T. Had the kit in hand and decided to call IRO. He suggested the tc drop instead. Glad I called. Said the front shaft would be too long to just install at 2" if lift. You might be okay 3 or above. The tc drop solved my vibes. I have a H&T kit brand new if your looking for one. Not going to use it. By the way, I found an app by TREMEC that is a driveshaft angle calculator that is really helpful in getting the driveshaft angles measured.
 
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