I'm just curious to know what all transmission options I have to bolt up to the L6- I'm thinking about swapping out the AX-15. Did they ever run a T-5, or a NV3500 behind the L6? Anything else? ZF? BW?

 

the NV3500 bolts right up, TJs used them. as far as getting it to work correctly, I have no idea.

 

Farmfuel, the AX-15 is a pretty good tranny from all I've heard. I personally have AW-4 autos in both of my XJs but, I've heard all good things about the AX-15. Why are you wanting to swap it out? Just curious.

 

I've got an old friend that's been building transmissions and gearboxes for years, and I told him of my tranny problems. It scratches between 1st and 2nd. He says this is a common problem due to the blocking rings being made out of soft brass. He says the syncros are next if I keep driving it. He says the AX-15 and the AW4 are both Toyota made. I have no problem with a Jap transmission, but he says that even the rebuild kits he gets are supplied with less than ideal blocking rings. He says that everything in that box is pressed onto shafts, and that nothing "just unbolts". He says its no fun at all to overhaul one. The rebuild kits are kinda high dollar as well. The T-5 parts are a dime a dozen, the bellhousing unbolts, etc- so I thought it may be an idea. They ran a T-4 behind the 258, but that would be mechanical clutch. It's probably no trailer pulling transmission, but they can be beefed up, unlike the AX-15. The Ford M5OD has the same problem with the soft brass blocking rings. I'm kinda turned on to the idea of running a 2WD NV3500, but the bellhousing doesn't unbolt...I guess I could get a TJ front case half, then run a 2WD Chevy rear case half- maybe that would work. I'm the king of wasting time.. The Mercedes Benz OM617 diesel conversion will be taking place late this year, or early next- and I'm liable to just run the auto that's behind that engine; they're pretty stout (but I hate autos)

 

The NV3550 saw some use in 4WD applications behind the 242ci I6. You can find it in 2000-2001XJ and 2001-up TJ (I think - it may be 2001 for both.) The NV3550, I understand, also accepts the bellhousing and related parts from the "external" (1994-up) AX-15, so you can also look for it in the later Dakota and some other light trucks as well.

Brass is pretty easy to harden - heat it up and let it air-cool. Ditto bronze. However, I think you want your synchro rings to be fairly soft - although I can't recall why offhand. Degree of hardening is largely controlled by the level of heat applied, with cooling time being a secondary factor (the faster you cool it, the less it hardens.) To soften ("anneal,") heat to red hot and drop in oil or water to quench. Yes, I know this is backwards from how iron alloys behave. Just trust me.

So, you could harden your brass/bronze synchro rings somewhat by putting them in the oven at 450-500* for about an hour and a half (let them heat through,) then turn the oven off and let them cool overnight with the oven door partially open.

And, make sure you don't use any GL-spec oil higher than GL-3 - beyond that, there's too much sulphur added to the oil (as an EP lubricant) to let your synchro rings last very long.

AX-15 and NV3550 are pretty much the easiest swaps. Anything used directly behind a Gen-2 or Gen-3 AMC V8 should also bolt right up, and I've heard tell of the NV4500 being adapted to fit behind the 242ci as well. I know it takes some sheetmetal work to fit into the XJ, I don't know about other models.

What are you trying to do, and why for are you doing it?

 

I'm towing my trailer, and the AX is making some growling sounds in low gear. The Getrag G360 behing the early VE pumped 6BT Cummins had a problem with a small input shaft bearing, and made the same noises when under load. You could overload that transmission- then Dodge started putting the NV4500 behind the 6BT.

If I have anything REAL heavy, I'll use my truck to pull it, but around town, (and even on the hwy)- the Cherokee averages better MPG than the IDI 7.3. I also blend vegetable oil for the truck, in an effort to cut down on the fuel cost...but it's still easier/cheaper to operate the Cherokee. (ask me again later when fuel goes back to 4.00/gallon)- I'll be driving the diesel running straight vegetable oil then.

I was just weighing my options with regards to the transmission swap. I'll probably end up overhauling the AX if it can't get me through the rest of this year...but I hate sinking money into something that won't be used much longer- going back to the Benz diesel swap I talked about earlier.

I was looking for a bolt in swap- something that could be found at a JY (was hoping a T-5 might have been used) There's no TJ's at the JY, and if there were, they'd want top dollar for the gearbox- screw that