a popular swap from the ax-5 is the ax-15 and nv3550, among others. from the articles and posts here and elsewhere something occurred to me-that a better swap is or could be the toyota r151.

notice these gears ratios:
AX15 - 3.83 2.33 1.44 1.00 0.79
AR5 - 3.753 2.26 1.37 1.00 0.729
MA5 - 3.753 2.26 1.37 1.00 0.729
R150 - 3.83 2.062 1.436 1.00 0.838
R151 - 4.31 3.32 1.52 1.00 0.83
R154 - 3.25 1.95 1.30 1.00 0.75
NV1500 - 3.940 2.37 1.49 1.00 0.83
NV3550 - 4.01 2.32 1.40 1.00 0.78

it seems that the r151 has a better first gear than the nv3550. also, it has a fifth gear of 0.83, which is closer to the original ax-5 to keep the rpm's at their most efficient (whatever that is, though in my swap i've noticed a difference in fifth overdrive).

notice this:
All AX15's, AR5's, MA5's, NV3550's, R154's and Toyota R150's (built after 1996) are LONG SHAFT\LONG BELL. To use one of these in a SHORT SHAFT\SHORT BELL application requires a 1" spacer available from Dellow Automotive or Castlemaine Rod Shop in Australia.

therefore, it seems possible to match a 2.5L engine to an r151 with the dakota bellhousing to get that deeper first gear and better overdrive. the only question would be as to which x-case to use--toyota or jeep--and if jeep, are there adapters, as well as the length to determine driveshaft angles, etc. what do you fawkers think? :flipoff2:

Stinger on this board put a 904 behind his 2.5 and said he liked it. He is running some 39.5'' IROK's on D44/D60's with i think 5.38's. Dont hold me to it, but he did tell me he liked it better than a stick.

Any other info on the 904 swap? I am looking at doing the same swap behind my 2.5 with an atlas and klune.

904's came behind 2.5's from the factory, should be an easy swap.

R151 should be easy as well, a w56 will bolt to a 2.5L so there is no reason for the 151 not too. The lower 1st in the r151 would be nice :).

Run the r151 with a toy reduction box, OTT adapter and d300, flipped or standard.

2.5L/R151/toy box/d300 nice stout reliable setup IMO

When i build another YJ, it will most likely be a 2.5 with toy tranny/box and d300, with the 2.5 moved forward you have tons of room for dual cases. I only moved my current setup 4" forward and fit my 2.5/ax15/203/300 setup easily. The 151 and toy box would be wayyyy lighter than my ax15 203, the ax15 and 151 will be very close in weight but the toy crawl box is considerably lighter than the 203. My 203 box weighs 110 lbs.

You could easily run dual toy cases but i love my twin sticks on the 300.

therefore, it seems possible to match a 2.5L engine to an r151 with the dakota bellhousing to get that deeper first gear and better overdrive. the only question would be as to which x-case to use--toyota or jeep--and if jeep, are there adapters, as well as the length to determine driveshaft angles, etc. what do you fawkers think? :flipoff2:

Since I wrote up the material you're quoting, I guess I'll have to set you straight. You CANNOT use an R151 with a Dakota bellhousing behind a Jeep 2.5l The input shaft is too SHORT. The R151 was built before 1996 and has a 6.5" input shaft. The Dakota bellhousing was designed for the AX15 and is too LONG for the R151. They will physically bolt together but won't work together. All Toyota R150's and R151's built before 1996 have short shafts and won't work with the Jeep bells. I'd hoped I'd made that point clear.

Also, you CANNOT use the Toyota W56 behind the Jeep 2.5. Although they will bolt up together, once again, the input shaft is 6.5" and too SHORT. The ONLY situation that I'm aware of where the W56 CAN be used behind a Jeep AX5 bell is hooking it up to a Chevy 2.8/3.1/3.4 V6. And that if you use a Camaro/Firebird neutral balance flywheel ONLY. It's so thick, it pushes the clutch disk back far enough for full spline engagement. Now unless you can stick that onto a Jeep/Dakota 2.5, you're out of luck.

http://www.jeeps-offroad.com/showthread.php?t=4740

Greg

why cant you swap the ax15 input into the w56 and then you have the corrrect length for the 2.5L bellhousing? Arent the internals mostly the same?

I wasnt aware the 151 had a short input as well. I am not familiar with this tranny, will the ax15 input fit in it as well?

Follow the Greg's link. Very cool info.

And for the newbie who copied it like it was his, and still couldn't get it right: :nuke:

why cant you swap the ax15 input into the w56 and then you have the corrrect length for the 2.5L bellhousing? Arent the internals mostly the same?

I wasnt aware the 151 had a short input as well. I am not familiar with this tranny, will the ax15 input fit in it as well?

http://www.jeeps-offroad.com/showthread.php?t=4740

Follow the link above. Go to item #4 and #6. I hope that explains everything.

The W56 shares no parts with the AX15. I have heard a rumor that the AX5 input shaft can be swapped into the W56, but, I can't verify that. The AX5 is a US spec version of the Toyota G54. Better ask Marlin.

Greg

I asked Marlin a lot of questions about this exact topic. We talked FOREVER about it.

The one thing that I came out of it with is that you CAN swap the input shaft/bearing retainer from a pre-96 R150/151 with the early AX15, but the later models won't work because of certain "refinements" to the newer boxes. There is also a lack of interchangability of certain models because of differences in the Input gear, counter shaft and 4th gear depending on what you are trying to do. Basically, the jist of the whole thing was that it isn't as simple as it appears on the surface so you should be prepared.

The one thing that I came out of it with is that you CAN swap the input shaft/bearing retainer from a pre-96 R150/151 with the early AX15.

From what Marlin has said, Yes you CAN physically swap the AX15 input shaft with the R150/151. BUT, if you swap it into an R151, you LOSE the first gear and you're stuck with the Jeep first gear ratio. So why bother?

You might find this info of interest. "Fast Eddie" over on the International Harvester (Binder) Board is putting together a "Hybrid" tranny for his diesel Scout. He's going to use the Jeep gearsets in the Toyota case. http://www.binderbulletin.org/forums/? I'll post his comments:

"'Bout a year (or so ) back, I lucked into an old '70's-era SAE #4/GM SM465 clutch cover.

Intially, I was going to use a Jeep T-5 transmission and transfer case; the Jeep tranny guts were going to go in a bare NOS GM T-5 case I picked up on eBay (cheep, too).

I got talked out of the T-5 thing really quickly; they have no GVW to speak of, and used Jeep T-5 and the t-case go with 'em are an "in-demand" item, i.e., $$$$$$$$$$$ for a POS transmission.

An alternative I staggered across about that time was the (then-new) New Venture Gear NV 3550, a five-speed OD current-Jeep transmission with a decent GVW that both Dodge and C$%^&vy use in their 1/2-ton V-6 (and maybe V-8--I don't know) pickups. Inference--plenty strong for my purposes, and weight is around 107-lbs.

Advance Adapters sell this tranny new, along with an adapter plate...for Ford transmission bolt-pattern bellhousings . Well, I need a plate for a GM bellhousing, and guess what?

WHAT?

Advance only sells full bellhousings, i.e., block-to-transmission face, for GM bolt-pattern transmissions. (I may have mumbled a few bad words to myself when I found this out).

Now, I have been collecting and studying Advance's new catalogs as they come out, and I came across this interesting tidbit that was in one (and only ONE) previous catalog: "We refer to the NV3550 bellhousing bolt pattern as the AX-15 bolt pattern..."

Hmmmm. Further research in professional-level transmission parts houses confirmed the fact: The NV 3550 and AX-15 five-speed OD transmissions were indeed directly interchangeable, when in Jeep specification...because the Dodge Dakota also used the AX-15.

They don't break, used ones aren't in any huge demand, and I picked one up off eBay...cheep.

You see, it was at that same time that I found an AX-15/GM adapter plate in Novak's catalog.

Now it gets interesting: all these same catalogs hinted at the fact that the Toyota Supra R-154, and Toyota truck R-150/151 were the same transmission! (The professional-level catalog even went so far as to write that the Aisin transmission is a TOYOTA design!)

I picked up an '89 FourFunner V-6 tranny, t-case (passenger-side front drive drop), driveshafts, crossmember, blah blah blah off eBay.

Side-by-side, they are indeed identical--externally except for input shaft and case rear halves.

The Jeep's input shaft is 7-1/2" long, 1-1/8" 10-spline (classic GM size, what a coincidence ) and I have to have that length because of the adapter plate and old '70's bellhousing.

The plan is to use the Toyota case and mainshaft, Jeep gearsets and countershaft. I think it'll work--all the bearing and seal P/Ns are the same.

They also list this transmission as the current 5-spd. in the T-100, a 1/2-ton pickup, so I'll upgrade where possible, plus Marlin (of "Marlin Crawler") has some beef-up parts as well that'll waft their way in (and no, unfortunately I don't think a Crawler box will make it in...they are EXPENSIVE )

One of my guiding principles is to adapt to current, well-supported components, and Toyota is indeed well-supported in the marketplace.

Marlin has the Twin-Stick I'd love to use-but it works only with geared t-cases, not chain. In fact, to make my chain t-case work I'd have to buy a gear-drive reduction box and two separate adapter kits.

I mean, I've only got an engine set-back and all that entails, a fiberglass body, a rehabbed/breathed-on head, big-*** radiator, huge intercooler, convertible top, steering and both axle rebuilds, revised hydraulic power braking, a really cool intake and exhaust system, and a weird gearbox miscegination that may or may not work out, etc. etc. etc to buy or buy parts for, so extra gearing may have to wait... (maybe I have my priorities wrong? )

Why am I so adamant that I have to have a planetary-reduction chain t-case?

Simple: drivetrain efficiency, i.e., MPG; why do you think the industry has switched to planetaries to begin with? With front-drive deactivated, there ARE NO extra parts flailing around inside, as there would be with a bull-gear/idler gear/front-drive gear setup.

But: with a reduction-only range box in-between tranny and final t-case, I would gain crazy-low off-road gearing while running crazy-high highway final gearing, which could possibly offset any theoretical inertial losses through the reduction gearbox.

I kinda like the 3.73s in there now, and as this is a city stoplight-to-stoplight DD, the lower gears really help in getting the mess moving--but like you, I really think that 2200 rpm is the target number.

However, I'm going to hold off on any diff gearing revisions until the mess is completed--for the simple reason of weight reduction and revised CG, i.e., front/rear weight transfer. I've tried to project but there are just too many unknowns at this point.

(All that BS aside, it'll probably wind up 3.54...but I really like the 3.36 number, too).

I compared a T-428, a Jeep AX-15, and the Toyota R-150 in Excel:

Ratios V-6
3.0/3.4 4.0L
IH T-19 CR Toyota Jeep
T-428 Spread R-150F Spread AX-15 Spread
First 4.02 3.83 3.83
Second 2.41 40% 2.06 46% 2.33 39%
Third 1.41 42% 1.44 24% 1.44 38%
Fourth 1.00 29% 1.00 31% 1.00 31%
Fifth N/A 0.84 16% 0.79 21%
Rev 4.42 4.22






Ratio Spread Formula Component Mix
Ratio 1-Ratio 2 = X Toyota Input Retainer
Toyota Main Case
X Jeep input shaft
Ratio 1=Percent Drop Jeep gear set
Toyota main shaft
Jeep countershaft
Toyota Mid Plate
Toyota Rear Case
Toyota output shaft
Toyota shift rail/forks mechanism
Jeep shift tower and lever
Toyota couplers
Marlin Rear Bearing Plate


Note the Jeep gearset's more even spreads between gears, which was a pleasant surprise to me--intially, I was only going to use the Jeep's gearsets because I prefer to keep matched gear pairs together (I have to replace input gear because of input shaft; want to use input gears' countershaft pair; countershaft is probably a one-piece cluster-gear; meaning ALL mainshaft gears have to be paired, too; and they should go on the Totota mainshaft because they all use the SAME needle bearing P/N; and I'd have to use the Toyota mainshaft 'cause I'm using the Toyota t-case).

Another plus was the Jeeps higher OD ratio

In the meantime, the main thing to remember is this: $200.00. That is what a good, usable, Jeep V-6 AX-15 tranny cost me, less t-case; spline and bolt pattern both are direct fits to Jeep Dana 300s, if that is the way you want to go.

OTOH, a Toyota R-150 with first-gen chain-drive righthand-drop t-case cost me $300 (and that included mount, driveshafts--double-Cardan CVs ), crossmember, etc, as the R-151 w/4.3 First from the rare Toyota turbo-Four pickup made only a couple years in the mid-'80's, and a gear-drive t-case is the one everybody wants, and the price reflects this.

An R-150 as I described is basically only worthwhile as a core, if you wanna be rock-crawler trendy, pay da money. Or get the cheep version; if you're me, you'll be overhauling whatever anyway, so go to Marlin's website, and pop for his gearset with the 5.31 Low.

Again, if you're me, you'll want the chain-drive righthand drop t-case for onroad MPG and easy match-up to the RH pumpkins on the Scout, but RH-drop 23-spline input gear-drive t-cases (the one you want) are still cheap, plentiful, and some seriously sick low ranges are fairly easy and cheep.

For Scout Diesel guys, the down-side to the AX-15 (at this point) is still the cost and parts availability for adaptation at the engine end; with all the hard Toyota/Dakota/Jeepota info in the link Weber's given us, I'm wondering if there might be something affordable in there for us.

I'll eventually do a cost comparison, but I think

Man, there sure are a whole lot of little pieces in there...times two! Seems like the ones that are made of unobtainium are either spring-loaded and begin a trip to Mars via stored kinetic energy when knocked out of their groove, or have an affinity for the wire wheel and infinity

Actually, I didn't lose any, and I've been careful to refurbish, label the piece with my engraver, label the baggie they went in, and cross-index to the Toyota shop manual (a very, very well-done manual, too), and bag things up.

I'm pulling them both down, side by side, and taking digital images in quantity as I go. Both are down to mid-plates, shift rails and internal linkage removed, main and cluster shafts and gears still intact, and no, I don't think the Jeep tranny is going to be reusable in any form, not even as a core.

As a general observation, both Jeep AX-15 and Toyota R-150 are v-e-r-y similar (I don't want to say "identical") in the center section, i.e., past the point where the input shaft joins the main shaft and at the rear outside the mid-plate (which is the OD gear.)

The Jeep mainshaft (output) is quite a bit different from the Toyota at the rear, where is joins up to the T-case. The Jeep is longer, does not have its own bearing, and male-splines directly into the T-case; the Toyota is shorter, has a finer spline count, uses a sleeve-spacer, a ball bearing.

I.e., I am going to have to use the Toy mainshaft, Jeep gearset, Jeep input shaft, Jeep countershaft, Jeep OD gears.

Both use different mounting systems for the OD gears, but in both cases are demountable from the main and countershafts, so I'm cautiously optimistic that I'll be able to use the Toy OD gears on the Jeep countershaft and Toy mainshaft with the Jeep gearsets.

Needless to say, I have some careful measuring to do before I pull all the gear shafts off the mid-plate and apart!

(I WILL be putting up some pics before very much longer)."

Eddie

That's right about the 151 first gear. . .only reason you might want to do it then is to do a Toy doubler or Toy to D300.