NP242 upgrade

[SpreadEagle]

Just found a AX15 and NP242 on the list for $350 Sounds like a good price.. How easy of an upgrade is this from my current 4 speed manual? Or at a later date to a 4.0 upgrade?

[txjeeptx]

Price is right if its not broken in some way or worn out, or was used as an anchor underwater.

There are a couple different input shaft designs used by Jeep on the AX-15, one for internal slave cylinder bellhousing(pre '93) and one for an external slave bellhousing starting around '93 or so. None of the T-4 bellhousing, clutch, flywheel(different thicknesses), throwout bearing, or slave cylinder will work for the AX-15, so you'll need all that stuff specifically for the AX-15. You'll also need a shifter for the np242, different length driveshafts front and rear, and a rear driveshaft with the slip yoke on the transfer case(unless you also convert the 242 to a fixed rear yoke). Add in a transmission mount modification or a custom crossmember. Finally, the AX-15/NP242 combo is longer than the T-4/NP119, so you'll probably have to beat the floorpan upward under the driver seat to make a lil room(I did) or let the trans and t-case hang down a bit more than the stock stuff did. Oh, and the speedometer cable will possibly need some sort of modification.

It'll fit, but you'll really have to want that overdrive gear pretty badly to make it work.

Ah, and if your car has anything higher that 3.07 gears(lower number=higher ratio, like 2.35), then overdrive is useless.

Not trying to be discouraging, here, just letting you know its not just gonna bolt into place and be perfect or easy, even if the price seems too good to pass up.

[SpreadEagle]

Got that idea. Just know I need overdrive.Too many RPM's at highway speeds.

[captspillane]

That's a fair price, but nothing beats a T5 for simplicity and cost. They're very cheap, very plentiful, and just as good as any other transmission for a stock Eagle. Even with 4.0 Multi-port injection the T5 is a perfect choice, you'll just need a CPS kit that is still cheaper than an AX15 conversion.

Any AX15 can be mounted to a T4 clutch system using the NV3550 adaptor kit sold by Advanced Adaptors. The AX15 front bolt patten is dang near identical to the NV3550, so just one bolt needs to be fiddled with to use that adaptor. That lets you leave your flywheel, slave, bellhousing, and clutch alone. The bad part is that you need an AX15 pilot bearing installed (two types available but they both work on the 4.2L crank) and the kit costs $350. This is the best route to go if you have a performance AMC V8, but I doubt you're planning anything that extreme.

The internal slave type works with your flare line clutch system, but the nicer newer external slave type needs an adaptor. The simplest way is to buy another $140 Advance Adaptor kit.

For a NP242 upgrade your front driveshaft and rear driveshaft do not need to be replaced. In the front you toss whatever yoke that comes with your NP242 and use the original yoke from your Eagle NP119. Same splines, same front case casting, same dimensions once you switch the long yoke out for the short Eagle version.

On your rear driveshaft you need the slip yoke from an XJ driveshaft. It fits the original Eagle Ujoint perfectly. The only issue then is the slip yoke internal to the Eagle driveshaft. Disable this with a piece of 3" pipe and you're golden.

For an AX15 upgrade, you will change the length of your transmission by three inches. You still don't need new driveshafts if you find the right front driveshaft yoke from a junkyard Jeep, because there are several longer lengths available that still have the same Ujoint size. In the back you can just shorten the 3" disable pipe to make up the difference.

Speedo gets a huge upgrade by buying or grabbing a Jeep speedometer cable and an early XJ or Dodge Durango speedo adaptor. All readily available at most junkyards. Its a huge upgrade because you can now unscrew your speedo cable any time you feel like it without getting the fluid dumped all over you.

You can always use your Eagle speedo. It fits fine in the same hole. Once you get fluid dumped on you enough times you'll despise that speedo cable and order the Jeep CJ cable from Rockauto for about $20 bucks.

[carnuck]

Seems crazy that adapters would cost so much when they bolt directly to the motor. I would do the 4.0L starter, clutch and flywheel. (what I had planned for my rig before I broke my shoulder) I bought a TJ AX15 and NV231 then an external slave bell. It didn't seem that hard to put together with no special adapters?