M5R1 Question

I broke what I would call the output shaft on my 4x4 M5R1 in my 93 Ranger. Just to be clear, it's the splined shaft that mates to the female portion of the t-case. From the tech library, it appears to be #17, the mainshaft. I have a few questions:

1) It appears from the part descriptions that 93-94 ranger's use a different mainshaft than others. Is this true? If so, why, and what are the implications?

2) I haven't dug into the trans yet, so I'm not sure if I'm asking the right questions. What kind of a job is it to swap the broken mainshaft out for another? I can find another for about $100-$150. That sure beats a $700 replacement trans, especially considering there's nothing wrong with mine except for the broken shaft.

I've never dug into a transmission before, so I'm a bit hesitant to just jump in until I know what's involved.

You need to figure out why it broke. Mainshafts don't just snap because they feel like it. Overtorquing the transmission will break the input shaft, not the mainshaft.

I seriously doubt this is the only problem.

You should be able to find a transmission for FAR less than $700. You can buy a whole wrecked truck for well under that.

MAKG said:

You need to figure out why it broke. Mainshafts don't just snap because they feel like it. Overtorquing the transmission will break the input shaft, not the mainshaft.

I seriously doubt this is the only problem.

You should be able to find a transmission for FAR less than $700. You can buy a whole wrecked truck for well under that.

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Well, it broke because of a downshift from 2nd to 1st at about 3000rpm through mud and at full throttle.

I also had my doubts that this was the only problem, but everything turns fine by hand and there were absolutely no shavings at all in the atf that I drained from it. Not saying that there isn't something else wrong, just that what I've found so far has lead me to believe that. I think that what I really need to do is pull off the top cover.

I've been looking for a trans for almost 5 months now. The truck has been down for other reasons, so I've been able to take my time to find a deal. About the best I've seen is $500. Trust me, it's not because I haven't bothered to look.

So again, what's involved in replacing the mainshaft?

What you really need to do is DISASSEMBLE the transmission and look at every part under a bright light.

That's what you have to do to change a mainshaft, and it's also the ONLY way you can determine that the rest of the transmission is actually good.

MAKG said:

What you really need to do is DISASSEMBLE the transmission and look at every part under a bright light.

That's what you have to do to change a mainshaft, and it's also the ONLY way you can determine that the rest of the transmission is actually good.

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I think thats what he's asking HOW to do...

I haven't taken apart the M5OD myself, but from what I've seen, the transmission does have to pretty much be entirely disassembled to get the output shaft out.

I have yet to see a manual transmission for which that isn't true.

AllanD used to have a field-disassembly guide for one of these in the tech library. Is it still there? Aside from that, the factory shop manual or just trial and error are the best ways. DO NOT mix up the shims and spacers or you will not be able to reassemble it correctly.

4x4junkie said:

I think thats what he's asking HOW to do...

I haven't taken apart the M5OD myself, but from what I've seen, the transmission does have to pretty much be entirely disassembled to get the output shaft out.

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Yes it needs to be almost completely torn down.

It's not that hard to do. They are pretty simple. Don't feel like your the first to break a tailshaft. I broke one due to an improperly fastened T-case. The reason I do all my own work now.

Get yourself a piece of plywood and set it next to the trans. As you disassemble it place each piece in a line as it came out. Then when you put it all back together, you know how it goes in.

You'll have atleast 4 lines of parts going. So plan the room.

The hardest part is removing the large nut on the back of the tailshaft and removing the rear bearing. I made a wrench for the nut and just used a prybar and a chisel to remove the rear bearing. Taking my time as to not damage it.

One day when I get around to converting the 2wd M5 to a 4x4 M5 there will be a teardown article on the net.

I was able to get a output shaft locally for about $100.

MAKG said:

DO NOT mix up the shims and spacers or you will not be able to reassemble it correctly.

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There are none. If there are spacers they are thick enough and on diferent dia shafts to not get them mixed up.

BTW Be carefull as there are a couple of steel balls that may fall when removing the gears. Don't loose them.

That's why I say take your time.

If you got any questions I'll be happy to answer them. I have a 4x4 trans torn down in my garage right now. Allan will also be able to help.

CopyKat said:

There are none. If there are spacers they are thick enough and on diferent dia shafts to not get them mixed up.

BTW Be carefull as there are a couple of steel balls that may fall when removing the gears. Don't loose them.

That's why I say take your time.

If you got any questions I'll be happy to answer them. I have a 4x4 trans torn down in my garage right now. Allan will also be able to help.

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Cool, thanks for the help Joel. What was the name of the place that you got the output shaft from? I'm thinking it would be alot cheaper to get one shipped from Manitoba rather than the states.

MAKG - Yes, I just found the disassembly guide. Not sure how I missed it the first time. It's a little short, but it will be a great start.


Only one more thing I'd like to know - is this mainshaft 93-94 specific?

brendank69 said:

Only one more thing I'd like to know - is this mainshaft 93-94 specific?

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No

But it's guaranteed to be a M5OD for that year. IIRC the FM146 was still used here and there untill the 93's came out. Then it was M5OD across the board.

The FM146/FM132 was used ONLY on 2.9 engines from 1988-92, everything else was already using the Mazda trans.

After '92 the 2.9 was discontinued.

Yeah, there are a grand total of TWO selective fit spacers in a mazda trans
the 3-1/2" diameter one for the input bearing and the 2" diamter one for the countershaft, no skinny shims.

And that "field assembly guide" was all I wrote about it in one spot because that gets you past the worst part of disassembly.

A few notes I should make...
1)NEVER mess with the big "torx nut" that is the adjustable pivot
point for the 5th-Rev shift bellcrank.
2)don't disassemble the reverse idler gear from it's shaft, simply unbolt the shaft from the side of the case (the 17mm bolt head on the passenger side of the trans)
3)Don't remove the 5th reverse fork from the guide shaft it rides on.
Remove the bolt that retains the shaft in the case and it slips right out.

AD

AllanD said:

The FM146/FM132 was used ONLY on 2.9 engines from 1988-92, everything else was already using the Mazda trans.

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That wasn't always true. I've seen a couple 90-91's that have had the Mazda behind the 2.9L

What I was getting at with my statements was because of the overlap in years the parts books will have 2 listings for 2 different output shafts. If you don't know what trans you have you have a 50/50 chance of getting the wrong one. But in 93 they were all Mazda's so you shouldn't have a problem.

AllanD said:

3)Don't remove the 5th reverse fork from the guide shaft it rides on.
Remove the bolt that retains the shaft in the case and it slips right out.

AD

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I'll have to remember that. The ball bearing and spring are a PITA to get back on and have the sycro stay put on the shift collar.