NP242 Hack n Tap

I've been all over the internet the last couple of days trying to determine the answer to one simple question...hopefully you XJ experts can help me out.

When doing a Hack n Tap kit, such as the one offered by IRO, on a NP242 in a 1992 XJ, why do I need to buy the seal flange and seal?

Why can't I simply drill the end of the shaft out without cutting it off, tap it and install the new yoke with the existing tail cone?

The reason I am asking is because I have purchase said IRO kit and seal flange and seal. However, if I cut the shaft short enough to allow the yoke to correctly seal with the new flange and seal, I will require a new custom drive shaft. I am in the unfortunate situation of owning a Jeep with an Np242 and Dana 35. I have pretty much the longest ZJ drive shaft known to mankind and it would still be too short as far as having any usable slip joint left. As I laid under the Jeep contemplating my situation, I thought...hey this should work if I simply drill the output shaft without cutting and maintain the stock tailcone and seal. Then I can use pretty much any front drive shaft I can find.

If I have to buy a custom driveshaft, I may as well put a JY 8.25 in as it would be cheaper.

The closest thing I can find that seems to do exactly what I am thinking is here:

www.ausjeepoffroad.com/forum/showthread.php?t=133634

Obviously he did some other things such as add bearings and such, so I am worried about engineering reasons.

Nor-10 said:

Why can't I simply drill the end of the shaft out without cutting it off, tap it and install the new yoke with the existing tail cone?

Click to expand...

I guess its possible. You'd need a fixed yoke that was the same outer diameter as the slip yoke in order for the seal to work.

Benefits to cutting it back are (1) shallower angle for less binding, (2) less leverage so less likely to bend the shaft, (3) less wear on the output bearing, (4) ability to use standard front driveshaft on the rear

why would you need a custom shaft? I had a 242 and D35 with a hack n tap SYE and a front shaft worked perfectly.

and why are you so against using the supplied parts?

I am not opposed to using the supplied parts. I would just like to avoid going the route of a custom drive shaft. Maybe there is something wrong with my Jeep...I don't know but if I cut the output shaft and install the yoke where it needs to be to be correctly sealed by the new seal adaptor I will need a shaft in excess of 33". I checked a dozen Grand Cherokees last weekend and I couldn't find one that long. The longest one I could find was long enough....almost fully extended.

I've looked all over and can not find one to suit my needs.

What did you take your front shaft off of? How long was its compressed length? How much was left in the slip joint when installed...compressed and extended?

stock front shaft from an xj man, works perfectly

Are you running a manual transmisison? That's about the only thing I can think of that would result in super-long driveshaft. And there are some WJ front driveshafts that are over 33"

Automatic transmission.

And sorry...I know you all think otherwise...but a stock XJ shaft...let alone the stock ZJ shafts that I have been able to put my hands on will not work on my Jeep. There is, however, one shaft listed in a spicer catalog that I haven't been able to locate that might work and that is for a ZJ 5.2L with the NP231 transfer case. They list it as being nearly 33" compressed.

Oh well...I suppose I'll figure it out.

Did you flip the rear leafs for longer wheelbase?

I did an add-a-leaf without taking the main leaf off.

Possible bad motor mounts and/or transmission mount?

As a follow up in case anyone else searches for this issue I checked one more junk yard and I found a front drive shaft on a 96 Grand Cherokee that was a tad over 33" long compressed. This allowed me to use the new seal flange and cut the output shaft where I needed it to be cut.
The ZJ it came off of had a 5.2L and an NP242. The drive shaft has a silver sticker on it with part # 53008427. I looked at over 20 Grand Cherokees and Cherokees and this is the only one that had a drive shaft long enough for my application, a D35/NP242 combination.

Nor-10 said:

As a follow up in case anyone else searches for this issue I checked one more junk yard and I found a front drive shaft on a 96 Grand Cherokee that was a tad over 33" long compressed. This allowed me to use the new seal flange and cut the output shaft where I needed it to be cut.
The ZJ it came off of had a 5.2L and an NP242. The drive shaft has a silver sticker on it with part # 53008427. I looked at over 20 Grand Cherokees and Cherokees and this is the only one that had a drive shaft long enough for my application, a D35/NP242 combination.

Click to expand...

D35 is rear axle should not have any affect on front driveshaft length

i think you misread my post.

My Cherokee has the NP242 with a D35 combination which requires a longer front drive shaft from a donor vehicle.

sorry I read it like you got the rear shaft from a ZJ with a D35