'93 Ranger M5OD Locked Up- Ideas?

[Woodtroll]

Folks,

I just had to go pick up my father about 3 hrs. away from home; his '93 2WD 2.3L 5-spd. Ranger seems to have the transmission locked up. He said the shifts between 4th and 5th were getting hard (this was at highway speed, 55-70 mph), and then a little later the truck started to shudder. He put it in neutral and coasted onto the shoulder, stopped, put it back in gear, but when he let out the clutch the truck moved just a little, shuddered, and the engine died. He restarted it, put it in reverse, and it moved just a little, shuddered and died, and now the transmission seems locked up pretty tight. The truck coasts fine with the transmission in neutral.

We've got it in my garage, and are going to drop the transmission out tomorrow night. Do any of you have any ideas as to what we may be looking for?

Thanks a lot,
Regan

 

[4x4junkie]

Sounds like he ran it out of fluid, in which case (I hate to say) you'll be looking for a new transmission.

A common spot for leakage on the M5OD stickshift is the shift rail plugs on the end of the top cover plate (shifter housing). Be sure to replace these if you happen to get a used (non-rebuilt) replacement transmission.

 

[Woodtroll]

Thanks, 4x4Junkie, that was my thought too after doing some reading here, but there is no apparent fluid leak. I have not had a chance to check the fluid level yet, though, so it may be low. We put a new clutch in this truck about 50,000 miles ago, and checked the fluid then and once since, but I did not know then that I should replace the shift rail plugs.

I sure appreciate your help!

 

[AllanD]

I'm willing to bet if you try to get the truck moving in 4th gear it might actually go

That will confirm the diagnosis that the input gear welded itself to the output shaft.

Classic pocket bearing meltdown.

AD

 

[schmoo]

i would guess an input or counter shaft bearing.
the pocket bearing wouldn't let it roll in neutral.

 

[thewhitepowerranger]

same exact thing happend to me on my 94' i still got the tranny layin in the garage.....would a rebuild kit from autozone come with everything to bring the hog back to life?

 

[schmoo]

maybe. only way to tell is take it apart.

 

[Woodtroll]

Okay, folks, you sure called this one right. Even though there were no obvious major leaks, and the casing was mostly dry, this transmission had ran almost dry, apparently through the shifter plugs, just as you said. The input shaft bearing is scrap, and the first two synchronizer rings (just behind the input shaft drive gear) appear to be galled together. This may not be the correct term for one or both of these parts, but I know they are part of one of the synchronizer assemblies. The first gear has two pairs of flats ground on it, adjacent to each other, and interrupting the teeth on the gear- these almost appear to be flats groound for a large wrench/ spanner to grip (?). The next one just behind it is bronze, and these two are stuck together (will not slip enough on each other to allow the teeth to align). The needle bearing between the input shaft and mainshaft seems to be okay, just by feel.

I found the exploded diagram on this site, and a one-page disassembly description that tells how to take the ouput housing off, and then the output shaft nut, but then it pretty much says, "and then take everything else apart". Can anyone point me to more specific instructions as to disassembling this transmission, enough to get the input shaft and first (forward) synchronizer cluster apart?

Also, can you tell enough by my description to give me the correct names for the gears described, in case they have to be replaced? The exploded diagram lists part names and numbers, but is not very clear aboout exactly which pieces on the diagram relate to the actual parts in the transmission.

I have worked on big truck transmissions, and old Ford toploader 4-speeds, but these things are a little different, so any help you might provide would be very much appreciated!

Y'all take care,
Regan

 

[AllanD]

Once you have the rear end of the transmission apart and BOTH front and read bearing retainers off you just kind s "bounce" the trans on each end and the bearing races and countershaft bearings fall out

Those "flats" on the input gear are for disassembly clearance

Because once both countershaft bearings are out of the trans the cluster gear sits low enough that you can slip the input gear off the output shaft and slip it out through the over sized front bearing bore. (that's why the cup for the front bearing is so thick
to fill in that big hole)

After that you tip the front of the mainshaft up and slip it out the top of the case

On your trans the input bearing is almost certainly NOT the cause, it may infact be burned "blue" but that is invariably a "Symptom" rather than a cause.
the "Cause" is either the little needle bearing inside the input gear that supports
the input gear OR the "float" bearing that 3rd gear rides on when it isn't engaged fails first (the real root cause oil starvation)

(you'll likely find that 3rd gear has welded itself to the float bearing journal on the mainshaft)

In a mazda trans the oil functions more as "coolant" than it does as lubricant, and a lack of that coolant and the trans WILL fail.
And you only start with 2-3/4 quarts.

I'm the mazda trans "guru" but I've seen five or six "Dead" transmissions
that literally had to be cut apart (either taking a torch to the mainshaft
or a sawsall to the case)


AD

 

[Woodtroll]

AllanD,

Thanks very much for your help- it is truly appreciated. I have to work a 24-shift at the firehouse beginning in the morning, but I'll print this off for my father and let him tinker with it tomorrow. I'll let you know what happens.

Thanks again, sir!
Regan

 

[Woodtroll]

THANKS!! and an update...

AllanD and everyone else who helped me out on this thread- a heartfelt "THANKS!" for your input, suggestions, and guidance. Without this resource, we would have been stuck spending $450+ on an "unkown" used transmission.

Disassembly of the internals revealed a trashed input shaft bearing with related damage- seals, plastic oil slinger ring, etc. The needle bearing and thrust bearing and bearing surfaces between the input shaft and mainshaft were undamaged. The input shaft bearing inner race was indeed welded onto input shaft, but Dad had access to a lathe with a grinder, and was able to remove the race and resurface the shaft back down to specs (he just retired as a shop foreman, after years as a master machinist- those skills and resources come in handy sometimes!). At least we didn't have to Sawzall this one apart...

The 4th gear synchronizer that was stuck to the input shaft gear, he said he polished up until it moved freely. I asked, "Isn't that supposed to be a friction slip fit to engage the gear?". He got this "Uh, Oh!" look on his face, but by then we had the transmission almost in, so we just decided to try it and see. Well, now it scrapes going into fourth, so this evening we just finished pulling it back out, so he can replace the synchronizer ring. The removal went much faster this time!

I'm counting this as a true success story- y'all were a great help, and I wanted to let you know how much I appreciate it! Take care, folks, and thanks again!

Regan