Okay kids: question.....
Recently bought a used 1981 f100. Dumped about $350 into making her run. Did fine for about a month....so, here's the dilemma ;
1) previous owner dropped a 1987 5-speed into her. It appears to be the Mitsubishi. From the start, the grounds were all disconnected, jerry-rigged and daisy chained and to be honest, i have NO idea how the heck it even started, and, after the first 3 days owning it, it chewed up and spit out the starter & selenoid. Easy fix, done & done.
2) previous owner mentions that reverse must be held manually in place, or it would jump half way outa gear. My first clue as to what kinda mechanic coaxed her into running in the first place. Clutch was gripping in the last 2 inches or so from the top, so, in my limited wisdom, i chose to ignore the possible short comings these guys had in their abilities. Shame on me.
3) now, I've been reading your threads here about switching to the hydraulic clutches with the M5R2, moving the cross member support, slave/master cylinders, gear ratios, etc. So, questions start now- my clutch is blown. Happened all the sudden, miles from nowhere...while bleeding the line with another Ford nut, Good Sam who just happened to stop n help me that fatefull night, I noticed the hydraulic line was just sort of wobbling round where it connects to the transmission. Gotta be a fix for that, right?
4) Some air gurgled out during the bleed process, it was refilled, pressure restored to the pedal (which sat on the floor by the time i pulled over), but still, no grip. Clutch is most likely blown, I'm fixin to replace and repair these farmer repairs and mods, and SELL IT, but I don't want the reputation of a lemon salesman, so i am wanting to do this right. Suggestions?

 

That 5sp is the Mazda M5OD light duty tranny.

Best thing is check to see of the clutch was soaked in fluid causing it to slip. With a clutch pedal on the floor, that fluid has to go somewhere and with a internal slave cylinder, the clutch usually gets the bath. If not, then it's clutch replacement time.


Bleeding these hydro clutches are not easy or fun. Took me a few hours to bleed out my clutch on my 84 F250 when the external slave went.

 

Cut your losses and sell it for parts.

 

Can't. I just can't.

 

Thank you. Looking at it, the tail end (ds) appears to be more conical than the m50d, how are you sure of that?
Also, the means of connecting the hydraulic line? Just kinda wobbling round. Slips in n out of trans 1/4-1/2".
Is it possible to visually see the clutch well enough thru the inspection port, or do i HAVE to take it out to see if its soaked?

 

Oops its a M5R2 not M5OD(used in the rangers).

The hose plugs into the slave cylinder attachment point is a few inches inside the bellhousing so the hose will wiggle outside the bellhousing.

If its soaked if fluid, you could try using brake clean and wash it off, but last time that happened to me, I had to take and replace the clutch. It was ruined by the fluid. That was after washing the clutch plate AFTER removing it from the truck and reinstalling it.....

 

FWIW, all manual 5 speed overdrives in Fords (or at least Ford trucks) are M5ODs. That isn't a specific trans name, it just means Manual 5 speed OverDrive.

I've seen the Mazda version (which I'm pretty sure was used on Rangers and definitely in half tons) called a lot of different things: M5OD, M5OD-R2, M5R2, "the Mazda trans". I'm not sure what the official name is, but pretty much any of those mean the same trans here.

The ZF5 is also an M5OD by the way, I think officially something like M5OD-HD, but no one ever calls it that, it always gets called by the name of the manufacturer, ZF.

 

If it's a Ford M5** 5-speed, it was made by Mazda (which Ford owned for a while) and not Mitsubishi, that's a minor point but may help you in your homework.

If it was mine, and I had all the confidence in the PO that you have in yours, I would just remove the thing (it's not really difficult but is a fair amount of work) as it's obvious that something isn't right and there could be multiple problems involved (God knows what other kinds of backassward mechanical adaptations were made besides what you've already found).

Do some homework on the gearshift popping out in reverse (I've heard of this before) this is likely to be inside the transmission itself and not related to the clutch mis-installation. Rebuild kits look to be available on eBay for about $150 (don't trust eBay sellers to know what they're talking about!) if you want to go there but you're really going to want a factory service manual and/or some sort of video on transmission rebuilding as this isn't something you "just do."

You might determine the thing is just toooooo hacked together & worn out to be worth any more money or effort, in which case I'm once again gonna suggest parting it out (I know you say you can't, to which I reply with: Can't? Or won't?).

 

Being it is an 1981 it would not have had that clutch setup or trany.
Maybe you could go back to stock setup on the clutch and run the SROD trany?
Just my .02
Dave ----

 

Thanks one and all regarding my old farm-mechanics truck.
I am looking into the reverse situation, no sense in repeating the monkey wrench job already performed.
Thanks again to Eddiec, and everyone putting in their $0.02, every piece to the puzzle helps. Turns out, they did move the cross member support to accomodate the trans, put in a floor pan, and that's why shift clearance was fine. Everything I've read outside my questions on other similar posts, goes into cutting the firewall to "fit" the master cylinder, but i see no such modifications there either.
As for bleeding the system, bench bleeding it off the rig seems to be the ticket, so, trying that while it's apart. Any other insights are surely welcome.
As for parting it out, it's not financially an option. That's all I'll say about that.

 

You're right, this was modified with newer trans, pre-purchase. Also, it's come this far, and can be done, so i want to see it thru as is. What a PIA it's going to be is largely dependant on doing my homework.

 

I hear you on fixing what you have.


My son had all kind of issues with the internal slave in his Jeep YJ, kind of turned me off to them.


As for the trany jumping out of gear may try looking into a rebuild kit and info on how to do it. I rebuilt a Ford WC T, was not that hard, that way and it does go into every gear but have yet to drive it.
Dave ----

 

Okay, a quick update on the trans, remember this is a unit from 1987 or so I'm told, installed on my 1981 I6,f100. So, the floor pan in the cab is aftermarket and fitted pretty well to the hump in the floor. Unbolted, removed gear shift arm and the ring, pulled the lid, and what i saw was a beautiful set of gears without blemish, forks with absolutely no wear, and no visual clue as to why the reverse gear has to be held in, in order to go in reverse or it just pops out of gear, so any ideas on this would be wonderful.
The tranny fluid was pretty, pink and hardly ANY dirt, no metal shavings, and none of the abuses you'd usually associate with hard use.
I'm beginning to think that indeed the clutch got soaked, and MY understanding is that once it's doused in hydraulic fluid, there's no cleaning it sufficiently enough to make it work properly. That's just my thinking, the units not out as of yet and only seeing will make me a believer. I just don't wana end up pulling it, to find out that it's a bubble in the line, or some other nonsense, easy fixes from the bench, barring one scenario.....the slave cylinder; I'm wondering, what year did the Japanese manufacturers of the 5 speed 2 rear wheel drive begin installing the slave that wraps around the shaft?
I know there's a few questions still unanswered, but slowly, thanks to all you guys' leads and ideas, the pieces of the puzzle are falling together. Again, many thanks.

 

OK my thinking on this.


The clutch only lets power go from the motor to the trany and would have nothing to do with it jumping out of gear.
Fluid on the disc could make it slip and/or chatter same as if it was oil.


On the forward gears IIRC the synchronizer is what helps get it into gear and hold it there.
Thing is reverse dose not have a synchro to help get it in gear or hold it there.
I would look at the reverse gear shift fork assy. as I think it could be bent and not letting it go fully into reverse and why it pops out.
Even more so when the trany heats up as it is now not going in as far as it was when cold.


Maybe if the input shaft bearing being bad but I would think you would see it in other gears also?
Just my .02
Dave ----

 

The YJ AX5/AX15 internal slaves are a pain, and the pre 89 peugot sourced BA10-5 is a notorious turd all around.

I wouldn't apply that level of pain to all internal slaves.