2.5/4.0 M50D Hybrid

My trans finally went out in my 4.0 4x4, so I decided now was the perfect time to try out an idea I had been tossing around. My truck has 3.73's with 33's, not as low as I would like, but better the 3.27's it came with. The 3.73's are nice on the highway though, and I drive 150 miles one way every weekend to and from school.

I was looking at the gear ratios for the M50D and I noticed that the 4.0 version is geared higher in first. second and third than the 2.5, 2.3, and 3.0 versions.

3.40 / 2.05 / 1.31 / 1.00 / 0.79 (4.0L Engines)
3.72 / 2.20 / 1.50 / 1.00 / 0.79 (All Other Engines)

Having a 3.72 first gear and 3.73 rear end will be like the having the original 3.40 first and the 4.10 rear end I wish I had, but 4th and 5th will remain the same and will make nice highway gears.(something I would lose with 4.10's outback, but eventually when I bump to 35's I will gear down to 4.56's or 4.10's)

I did a little math to figure the final crawl with the hybrid M50D
(first/sec/third all in low range)
34.41/20.35/13.88 (Hybrid M50D w/ 3.73 rear end)
34.57/20.84/13.32 (Stock 4.0 M50D w/ 4.10 rear end)

In third gear I will actually have lower final crawl than the stock 4.0 M50D w/ 4.10's

So I bought a 2wd 2.5 trans out of a totaled 99 ranger with less than 100K, but a 2.5 isnt direct swap into a 4.0 since the bell housing bolt patterns are different.

I pulled all the internals out of my 4.0 case and slipped all the gears, syncros,and bearings off ouf the output shaft and did the same with the 2.5 trans. I put all of the 2.5 gears and syncros and new bearings on the 4.0 shaft. (4x4 and 2wd trannies have different output shafts) I put the 2.5 counter shaft and the 4.0 output with new gear stack back into the 4.0 case.

If you were able to find a 4x4 3.0, 2.5, or 2.3 there would be no need to swap output shafts and the job would be a whole lot easier, but 2wd 4 bangers are a loet easier to find not to mention cheaper.

4.0 4x4

2.5 2wd

4.0 internals

2.5 with tail housing removed

gears, gears, and more gears!!!

the 4x4 shaft is the one w/o any gears on it

empty 4.0 case


Here are some side by side shots of the two cases


I snapped some pics of the shift forks that I pulled out of the 4.0 trans. They have about an 1/8 inch ground out of them.



The complete 2.5/4.0 Hybrid M50D

My tailgate made the perfect place to stand up the trans and bolt it down while I torqued the counter shaft and output shaft nuts.

I put it in the truck and took a test drive, it engages smoothly into all gears and is a lot quiter than my last tranny that had aluminum shavings for lubricant

The shifter from an older M50D and a newer one cant be interchanged. The base with the wedge bolt is clocked 90* and the newer shifter is about an inch further back. Which of course was enough to hit my center console when I shifted into 4th and reverse, so I made a temporary shifter to hold me over until I can get my Hurst in there.

old on the left and new on the right


I suppose a 2.9 M50D probably has the same gearing as my hybrid and would be a direct bolt in, but what fun would that be? Not to mention low miliage 2.9's are hard to find, and it seems like any 4x4 trans is 100 bucks more than a 2wd. I have heard the 98+ M50D's are supposed to have and improved lining in the syncros as well.

-plumcrazy

Can you feel that little lower ratios?

I'm kicking myself for not doing the worth myself....had two broke trans....one no 2nd gear. the other snapped output. shoulda saved me the $500 at the trans shop and make one good trans myself!

I do notice it, espescially at take off.

-plumcrazy

Did you need a press to pull the gears off?

Yeah, those gears are pressed on.

I built a 2.9 4x4 trans earlier this year. The trans came from the same truck as my HIPO 2.9 and I scored the output shaft and tail housing from 1badExplorer.

He sent me a bare shaft, so I had to do all the same stuff you did. I haven't run it behind a 4.0 yet, still trying to get my wiring worked out.

I bang/drop the whole gear stack against a block of wood and the weight of the gears will push the bearing right down the shaft. I use a press typically to reassemble, but have used a piece of pipe, an old race, and a dead blow to bang it on in a pinch (college campus parking lot trans rebuild)

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PlumCrazy said:

I bang/drop the whole gear stack against a block of wood and the weight of the gears will push the bearing right down the shaft. I use a press typically to reassemble, but have used a piece of pipe, an old race, and a dead blow to bang it on in a pinch (college campus parking lot trans rebuild)

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Is there any special tools or procedure for doing this Mod? i have a 94 2wd 2.3 m5od and a 94 2wd 4.0 m5od and am thinking about doing this. swynx, put this idea in my head. Also i never rebuilt a trans, not saying i cant do it. Just would like to know what im getting myself into. TIA!!!

Nothing too special, just a press and large crow's foot for the output shaft nut.

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Cool! I'll let you know how it goes! Thanks again.

Just got done doing the 2.3/4.0 hybrid swap. it wasn't to bad, just took my time and paid attention to what i was doing. Still a ways to go on my build, but its getting there.

Really interested in this mod. Is there any other way to see your photobucket pictures? Would I be able to search photobucket with your username???

My photo bucket was PlumCrazy 94, but I'm not 100% sure if the pictures are really helpful anyway.haha. My photobucket has zero organization. The first 20 pics I uploaded in highschool were organized........after that it was chaos

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Here's some pics from my thread

BlackBII said:

And the fun begins! Swapping the 2.3 M5od internals to the 4.0 M5od

This requires a 55mm wrench or large pipe wrench and a 32mm wrench or socket.

Finally get to use my giant 55mm wrench

This bearing comes off easy peasy with a pry bar on both sides

The rest of it is just simply removing parts until you end up with an empty case

This weekend I'll pull the other transmission apart and swap the internals, and then the drivetrain can all be put back together and the interior is next.

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BlackBII said:

Disassembly of the 2.3 M5od. This one needed a bit more persuasion.

Here's all the parts of the trans, from left to right in the disassembly process if anyone is curious. This is how I disassemble most stuff like this. It makes it easier to put back together.

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BlackBII said:

Here's some pages from the factory service manual for reference

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