M5OD inspection

[4x4junkie]

Well I picked up a Mazda to replace the Mitsushitty in my BII, but I sortof want to get a peek inside at the gears before I start tearing the truck apart.

Any surprises I should know about before popping off the top cover? (springs flying out? shims falling inside it, etc.)?
(Normally I'd just consult my Ford service book, except they're several hundred miles away right now, and the dudes that wrote the Haynes manuals apparently think we're all too dumb to take apart a manual transmission (forget about an auto ).

I pulled the drain plug, there was a small amount of black sludge-like material around the magnet (normal), and smells of ATF (not gear oil). Maybe I shouldn't even worry about it and just slap it in? It does seem to be in good condition...

 

[offroadranger]

I was worried about popping the cover off the first time too, afraid it would be one of those thinigs like the snake inthe peanut jar lol. But its not. pop that top cover off and you will be able to see all the gears and there is nothing to put back in place if you simply remove the cover, adn it uses a reusable rubber gasket, so nothing to worry about.

 

[MAKG]

Even if it didn't have a reuseable gasket, ultra black RTV works very nicely on transmission cases.

The one "gotcha" is that, unlike a Mitsu, you remove the stick without opening any part of the gearbox. If you see lubricant, you went too far. If you were in gear at the time, you're going to have lots of fun putting it back in. It's not impossible; just hard to do correctly.

I'd never pay money for a transmission I can't see gears on. DEFINITELY take the top cover off and look for pitting, weird wear, and other problems. It would suck donkeys to get this thing in and find out it's trashed. Especially if you find out the hard way (failure).

 

[TireIron]

yea, the biggest thing is make sure it's in neutral and dont retighten the bolts too much as they are threaded into aluminum and can strip it out pretty easily.

 

[4x4junkie]

So just be sure it's in neutral before taking anything apart? (I already went ahead and pulled the stick out to put new shifter bushings in it... I've done this in the past on my Ranger already as well without issue).

Got it.

Thanks for the info

 

[rickcdewitt]

lil' hijack here but,what might it mean if i found a small thrust washer or something mangled up when i pulled the drain plug.its been a while but i think it was steel,1/16" thick,1 1/2" diameter and the thrust surface about 3/8" or so(all approximate from memory).it was torn so as not to be a circle any more and ground/balled up against the magnetic drain plug.last i remember the tranny worked but the shifter bushings are sloppy.i'll get the cover off and see but i've never messed with anything but the old 4 speed saginaw trannies.thanks!

 

[Ranger44]

Yeah the stick being in nuetral helps alot when changing the bushings. Otherwise when you remove the stick....and put everything back together you'll find it woun't shift. Your gonna have to manually shift the rails back into N by reaching there with something and depressing both buttons and sliding it back. Took me a little for me to figure that out. LOL. Mazda 5spd uses ATF.

 

[AllanD]

lil' hijack here but,what might it mean if i found a small thrust washer or something mangled up when i pulled the drain plug.its been a while but i think it was steel,1/16" thick,1 1/2" diameter and the thrust surface about 3/8" or so(all approximate from memory).it was torn so as not to be a circle any more and ground/balled up against the magnetic drain plug.last i remember the tranny worked but the shifter bushings are sloppy.i'll get the cover off and see but i've never messed with anything but the old 4 speed saginaw trannies.thanks!

It's probably a piece of the shim that sits under the plastic shifter bushing.

there are NO thin shims inside a Mazda trans except for those in the shift tower.

AD

 

[rickcdewitt]

It's probably a piece of the shim that sits under the plastic shifter bushing.

there are NO thin shims inside a Mazda trans except for those in the shift tower.

AD

hmm i think i can envision how the shifter would go sloppy and the washer wind up in the bottom of the tranny at the same time,and could be related.at least i wasen't the one who put the rebuilt tranny in.i feel better about the tranny now,it doesn't sound catastrophic.thanks

 

[4x4junkie]

Yeah, that sounds about the size of the shims that go above & below the shifter bushings. (around 1.5" OD /1.3" ID, and about 0.5mm thick).

Anyway, took the cover off, everything looked excellent inside.
Not sure what to do with the old Mitsu yet, still driving it, noise doesn't seem to have gotten any worse since I first noticed it... (probably put another 1200 miles on it too) Maybe I can nurse it along until I get back home to where all my good tools are.

Thanks again for the help guys!

 

[rickcdewitt]

sorry 'bout the thread jacking^,i bet if you stay out of 5th you'll be fine for another 10,000 miles before it finally craps out.i ran mine even though i was getting large chunks of gear and bearing on the magnet when i flushed it every 3000 miles.i went for a few 500 mile drives in it that way.also when i first bought my truck for a thousand dollars the previous owner was very elusive answering questions regarding history and maintenance.the tranny made a little noise on the test drive and it went about 50 miles(sebastopol to cloverdale) making increasing noise all the way to the freeway offramp.when i went to stop it was stuck in gear and i had to pull over on the side of the road.i pulled the tranny drain plug and what do i see?nothing!not even a drop of 90wt on the plug.so i walked to the nearest quicky mart and got some gear oil to get home on.i then had to start it in gear and shift it like a big rig into third and go the remaining 18 miles home. moral of the story? these are some pretty tough trannies even if they aren't as strong as an m5od,you should be able to drive it til you can get at your tool box.

 

[MAKG]

You really can't guess.

At some point, the transmission will stop moving the vehicle, possibly with no further warning. It MAY be a long time, or it may be 10 miles from now.

What you have to answer is, can you live with that? If it were me, I'd make sure I had my AAA Plus card, the replacement transmission, and basic hand tools. You don't really need much more than that to R/R a transmission. You can even skip the starter if you really need to (but secure the starter cable or you may destroy the battery). The transmission is the exact same length, so you don't need any major drivetrain parts aside from the transmission and its stick. You may need to leave the hump plate open.

The only special tools you need are a pair of $3 ratchet straps to lift the transmission and transfer case. If you're a big guy, you may be able to bench press it in (you know how heavy it is now). I'm not big enough for that....