Rebuilding the Mazda M50D-R1

[Bill G]

Start with basics:
1992 2WD 2.3 with the Mazda M50D-R1 transmission

One or more of the bearings are making noise. I have taken it upon myself to replace the bearings and anything else damaged.

I have taken the transmission out and have partially taken it apart. I have read Allan D's field stripping guide but have questions about removing the staked portions of the nuts for the tail shaft and the counter shaft. What is the easiest way to remove the staked portion? It looks like if I were carefull I could just drill that section out. What has everyone used to remove that portion? Once it is removed how much torque is required to remove the large nut? Does it come off pretty easy, or am I going to have to find three grown men hold it down and use a 6 foot cheater bar?

 

[MAKG]

A die grinder (or a drill) will take care of it. IF you can get a screwdriver underneath it, you can pry out the "stake" rather easily.

Or if you have replacement nuts, you can just force them off. The threads on the shafts are hardened, so you won't do anything to them. But the nut is going to tear.

I believe the nut is spec'd to 100 ft-lbs or so. You will need something to keep the transmission from rotating. I've been known to put the case in my press (very lightly). That triples the transmission's weight....

If it gives you trouble, CUT the nut off with a dremel and cutoff wheel.

 

[90B24wd]

That's what I did when I stripped my trans. It was easier for me to drill out the staked
part of the nut before removing it. Becareful you don't ruin the threads.

 

[AllanD]

I don't bother.

Loosening the nut "irons" the crimp out of the nut.

The staking collar on the nut is MUCH softer than the shaft.

I just buzz the nuts off with a 1/2" impact gun.

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[Bill G]

Finally finished the teardown this afternoon. I found that the front countershaft bearing has failed. The plastic scoop ring on the input shaft is nothing more then a melted pile of goo now. I can't even tell what it used to look like.

Can I use some emery cloth to clean the bearing material off the counter shaft or should I start looking for another shaft?

All the other bearings spin well but look like they took some heat. I guess I will replace them all being I have the transmission torn down all the way.

Is there anything else I should be on the look out for?

Also does anyone have a good place to get parts? I have looked on Ebay along with Autozone and CSK.

 

[blind029]

Well as far as parts go, here's a couple web sites, i have been researching for my rebuild as well:
www.drivetrain.com
www.mackstrans.com
www.eatmyshifts.com

the last one i think only has a rebuild kit, but you should be able to get parts from the other two

As far as other things to look for it sounds like heat was your culprit, make sure you don't have the rubber seals on the back of the top cover. You can look at my thread to see the damage from those leaking. I'm sure you've heard about it, but just be sure cause i'm having loads of fun from that problem...
If your comfortable with the way the gears mesh and transmission operates you don't need to worry about the shims in the front cover, but i can give you those specs if you want to look into that as well.
Torque for the output shaft is 160-200 ft lbs, countershaft: 94-144 ft lbs

 

[MAKG]

ALL the bearings show heat damage?

If that's really true, recycle your transmission and get another. It's ruined. That's a sign of oil starvation.

As for whether you can reuse your countershaft, look CAREFULLY for any signs of pitting, cracking, discoloration, etc. Depending on just how much heat it saw, it may have lost its hardness. Pitting in particular indicates parts of it were melting.

 

[Bill G]

I bought a complete rebuild kit from southwestgear.com for $276.00 to my front door. You can buy direct from them or they have a lot of parts listed on Ebay. I got all the bearings, seals, input shaft, countershaft, syncros, nuts, and shifter bushings. The only things I'm reusing are the mainshaft, gears and hubs. I recomend them for parts as I ordered on Sunday night and they were at my door on Tuesday afternoon. They have or can get any part you will need.
Junkyard transmissions are near $500.00 here and I haven't been able to find anyone parting a 2.3 Ranger with 5 speed. Lots of automatics though.

 

[rboyer]

You should have asked around on here! I myself have a couple of 2.3 transmissions laying around at the moment. And I do believe that AllanD keeps them laying around for doorstops until he needs them to use as "organ donations" for transmissions that are more worthy of having the parts in them.

 

[Bill G]

You should have asked around on here! I myself have a couple of 2.3 transmissions laying around at the moment. And I do believe that AllanD keeps them laying around for doorstops until he needs them to use as "organ donations" for transmissions that are more worthy of having the parts in them.

I would have paid half as much in shipping to get a trans to rural Arizona as what I have in new parts.

 

[rboyer]

Yes but for $99 more than you spent in parts you could have a good trans shipped right to your door.

 

[Bill G]

Does any one know what the end play should be on first gear? I'm not sure if I seated the center bearing completely. I have about .006 of play in the gear set and the bearing doesn't seem to want move down anymore.