M5OD work thread - WTB parts? | Ford Explorer Forums - Serious Explorations

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M5OD work thread - WTB parts?

Nick26

Explorer Addict
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City, State
Cumberland, RI
Year, Model & Trim Level
98' 5.0 XLT
M5OD rebuild thread!

So I'm driving to work yesterday on the highway with it in 5th and then all of a sudden I hear this crunch and metal on metal grinding noise. Then the engine started revving (cruise control), 5th gear had turned into neutral. I pulled over right away and luckily the other gears all still worked so I could limp home. I guess 50K miles on 32 inch tires without regearing the stock 3.73 gears must have put some extra stress on the trans. Not to mention most of those miles were on the highway in 5th Gear.

I think I am going to rebuild this trans, seeing as I can get away with driving my mustang for another month or so hopefully but another option I was thinking was to perhaps install a M5R1-HD which I thought was heavier duty? Does anybody know if this would work? Is the bellhousing the same?

Suprisingly, I didn't find all that much info on here as far as rebuilding it... Spdrcer34's thread had potential but he never finished it. And figures therangerstation.com, which has a pretty good tech library, just recently got hacked and its not up right now.

It has 120K on it, so what would you guys think the condition of the synchros would be? definitely replace/possibly/or could they be fine? With 120K on it and the fact that I have it all apart to fix fifth gear I figured I should probably go through the trouble of rebuilding it all, but then again I don't know. Is that even a lot of miles for a tranny or do they typically only need a rebuild after like 250K?

If I went the rebuild route would this kit contain everything I need (aside from whatever is broken)?
http://cgi.ebay.com/ebaymotors/Rebu...008QQitemZ180044173286QQrdZ1QQsspagenameZWDVW
Can anybody recommend a good cheap place to get a rebuild kit? How about were to buy the replacement parts I'm going to need?

Any one know if this trans changed after 97? Some sites like this state that their rebuild kits are only good for 91-97 explorers: http://www.drivetrain.com/mazdaM5R1.html


As I go through the tear down and assembly of this I'll be sure to take and post lots of pictures on here. I'll post any thing thats specifically useful off the ford cd I have as well. Now I'm off to construct a gear puller....:(
 



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Check WWW.Eppys.Com for those specialty tools. He could probably get it even if it's not on his website.

cool thanks, i looked at the site briefly but I'll look again when I know what tools i need.

other than that, started pulling the tranny...
 












In case anyone is wondering a BW 1354 manual with fluid weighs exactly 68lbs and a M5OD with no fluid weighs exactly 91lbs. I managed to get both of them out by myself and did not touch the Y-pipe.

Started tearing things down...
 

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Suprisingly there is no metal chunks in here at all. The magnet on teh plug was full of grindings though. I guess it's not going to be as obvious as I thought to figure out where 5th gear went.
 

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I see that everything looks pretty much straight forward. It is basically a bunch of gears, and bearings. There is nothing electronic, and no valve body with small parts to get lost, and clogged. Did you make a list of specialty tools like bearing, and gear pullers? I saw some snap rings in the above picture.
 






I see that everything looks pretty much straight forward. It is basically a bunch of gears, and bearings. There is nothing electronic, and no valve body with small parts to get lost, and clogged. Did you make a list of specialty tools like bearing, and gear pullers? I saw some snap rings in the above picture.

I didn't end up really needing any specialty tools after all... I just followed the directions here: http://www.therangerstation.com/tech_library/MazdaTransDissasembly.htm

As a work stand to set the trans on the floor (or ground)
I use a 4-foot length of 2x12 with a 3/4 hole bored into the middle of it.

The hole is for the input shaft which protrudes slightly from the bellhousing

with the trans standing on it's bellhousing with the tail shaft housing removed and using either a mototool or a "cape chisel" remove the "staked" portions of the two nuts on the tail shaft and countershaft.

Now lock the trans in two gears at the same time (With the top cover off push both the 1-2 and 3-4 synchro collars "down")

Using the two LONG bellhousing bolts at the
10 O'clock and 3 O'clock positions to prevent the tranny from rotating use a pipe wrench to remove the main shaft nut.

If you don't have a pipe wrench use a large chisel against the flats of the nut to drive it off (the nut is not re-usable anyway)

Repeat procedure for countershaft nut though for that you may actually have the 30mm socket you'll need.

Now, flip the trans bellhousing up (a garbage pail half filled with paper makes a nice work stand) remove the front bearing retainer.

Remove trans from garbage pail and put it back on the wood block.

Using a pry bar to apply upwards force on the rear bearing strike the end of the output shaft with a brass or lead hammer.
Rotate shaft between blows until you get the bearing off.

At this point it's all 12mm socket work and simply disassembling things in sequence, but will generally get you into whatever parts you have screwed up.
 






Here you can see a close up of the staked nut on the output shaft.
First I used a dremel tool with a grinding bit and ground out as much of the dent as I could without damaging the shaft.

Then I made a narrow chisel tool out of a an old precision screw driver I had and slid it down the groove to pry up the remaining metal.

Then to get this nut off I notched it and just used a screw driver and a hammer to spin it off. This nut is only good for one use so its ok to notch it and all. Otherwise you could use a pipe wrench but I didn't have one.

I did the same precedure then for the smaller nut on the second shaft. This one I was able to get a crescent wrench around, it looked like it was 31 mm though if you wanted to buy a socket.

Then lastly to get the bearing off I used a prybar and a rubber mallet. Just be sure to rotate the shaft 180 degrees after every few wacks.
 

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OK, so here's the million dollar question: What broke? Nothing looks all that bad, and typically a grinding noise in 5th would leave some more clear evidence. Any excessive wear in the teeth? Any slop in the shafts?

I vaguely remember seeing something on the Omega Engineering web site about parts for an M5OD... might be worth looking into. IIRC, their parts addressed some of the weak points of the M5OD.

-Joe
 






haha good question... After playing with all the collars and shifting it in and out by hand I verfiied that the shafts do spin freely when it should be in 5th gear so its not a problem with the shift forks it seems. I am thinking that the dog teeth gear for 5th which slides into the collar broke some how. But again, there is no broken pieces inside, unless they all washed out with the fluid(I should check). I haven't gotten to that point yet, I plan on breaking it down more tonight.

Thanks for the tip on omega, I still haven't figured out where I am going to get the replacement parts other than maybe driving to the local cottman or aamoco and asking if they will order them for me. Although a search for M5OD on there site didn't turn anything up, do I have the right company? http://www.omega.com/
 






Nope... I can never remember the dang site either... have to search..... Omega Machine.... Sorry, I always screw it up.

www.omegamachine.com

From the last line of the Cases section,
Mazda M50D Repair front case bores. Main drive gear or counter shaft area.

Looks to be all they have available.... I thought there was more for that trans, but I guess not.

-Joe
 












are you going to trya nd rebuild using the same parts or rebuild a HD version, im considering a M5od swap and this info would be great.
 






looks like you still have the rubber plugs in the shift rail end holes. they dry out and leak, making the top of the trans look wet like yours, and starving the trans for fluid. there is an upgrade to put metal freeze plugs there to fix the problem.
http://www.explorer4x4.com/tips.htm#tranny

FYI. I just swapped the 5 speed in my explorer last weekend. it was very noisy and difficult to shift(common problem). I got a rebuilt trans for 800 after shipping both ways from www.smartpartsauto.com New luk clutch and flywheel and it works awesome. total down time - one week.

-joshua:exp:
 






are you going to trya nd rebuild using the same parts or rebuild a HD version, im considering a M5od swap and this info would be great.

At this point I'm going to rebuild it using the same parts. I looked into the HD a little bit and found out that it has a different size input shaft and therefore practically every thing in the box would need to be upgraded. So i don't want to spend that kind of money, considering I'd need a new clutch as well(which Is pretty new because I just installed it like 30K miles ago). If the entire tranny was trashed then i'd probably look into just swapping in an HD with a new clutch, but so far its not so bad.
 






looks like you still have the rubber plugs in the shift rail end holes. they dry out and leak, making the top of the trans look wet like yours, and starving the trans for fluid. there is an upgrade to put metal freeze plugs there to fix the problem.
http://www.explorer4x4.com/tips.htm#tranny
Yeah I know about those but being in the north east they are far from drying out. I'll probably replace them anyway just for piece of mind. I've never lost any fluid though.

FYI. I just swapped the 5 speed in my explorer last weekend. it was very noisy and difficult to shift(common problem). I got a rebuilt trans for 800 after shipping both ways from www.smartpartsauto.com New luk clutch and flywheel and it works awesome. total down time - one week.
Thanks, but I've already come this far so I might as well rebuild it, but in the event it doesn't work out I'll look into that. I'm reading a lot that people put gear fluid in the tranny and that causes it to be difficult to shift and noisy, could that have been your problem with the other one?
 






ok so i found the problem... if you look real close in this picture there is a crack that goes all the way around the gear, separating the dog teeth and the actually gear.
 

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Here are some pictures of a couple syncros. I was wondering if any of you tranny experts wouldn't mine taking a look at them and telling me if they should be replaced? To be honest it shifted in and out of gear fine before this happened.(again look at my site for higher quality pics).
 

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