Early ford trans case: Rear thrust face. Repairable?

Mart

Mart

Well-known member
I have a 41 transmission, matching numbers for my pickup. The rear thrust face has been scored quite badly. Has anyone successfully repaired and resurfaced one of these? I have a lathe and small milling machine but am struggling to imagine how to go about even trying to repair it.

Mart.
 
These are probably things you have already discounted, being the master craftsman that you are Mart, but
Could you fill in the scored areas with a weld bead and then polish out, or could you cut out the bad section and weld in a new one from another transmission.
 
Welding castiron and getting it machineable is always tricky...we used to sprayweld heads and that gives a good colourmatch and surface that can be milled.
But that really takes an oven and any surface needs to be covered up to avoid splatter.
Machine it flat and ad a shim since you have a mill.
Drillbushing in each end and a boringbar with a cutter powered by the mill.
 
Had a customer at my old job, show me an Austin-Western gearbox case that he had a local machine do pretty much what flatheadmurre describes above.

I was impressed many times by the skills of the old-timers in small town blacksmith shops.
 
Yes, Ted, the face the rear of the cluster shaft thrusts against. Mine chewed up the thrust washer and has worn the casing quite badly. I think I might have to make a specific tool I was wondering if anyone has already done the same job.

The fact that it is deep inside the trans casing makes it a bit difficult to access.

Mart.
 
I once took old cluster gear--not on a Ford---ground a groove to hold cutter bit, advance cutter with feeler gauge at other end, kept adding .001, make a revolution, clean shavings, add another .001
 
Mart, without knowing what diameter tool and arbor you would need you might check into "reverse counterbores", they are sharpened for CCW rotation.These are typically used on a radial drill press or a counter-bore table. Hopefully there is a size that suits your application.
 
Mart said:
I have a 41 transmission, matching numbers for my pickup. The rear thrust face has been scored quite badly. Has anyone successfully repaired and resurfaced one of these? I have a lathe and small milling machine but am struggling to imagine how to go about even trying to repair it.

Mart.
Click to expand...

Fire a PM to Mac VP on this and see what he would suggest. I'm sure he has crossed this bridge before.
 
We worked with a machinist some years ago on this issue. He cut out the damaged rear thrust piece.....completely through the case. He machined a slug of steel in the same diameter of the whole that was cut into the case. The slug had the 3/4” bore drilled into its center and the oil groove to the inside. The slug was placed into the back of the case and then positioned so the inside face was placed at the same location as the original face. The slug was set into place with red locktite and three pins locking the outside diameter of the slug. When positioned correctly, the front to rear inside dimension was the same as a new case. I had perhaps 3 or 4 of these done. I’ve never heard back from any of those customers that they had any issues with the repair.

The downside to this......it cost me about $100 per case to have him do these. I could buy core cases for less back then so it wasn’t cost effective. On top of that, he told me that he didn’t want to do the work anymore.
 
Thanks for the insight Mac. That's far beyond my capabilities. I do have one more case from my dwindling supplies that I can build the gears into. I'll probably put this case on the shelf so the machining job does not hold up getting the vehicle back on the road.

Thanks for the help, all, I'll get to this one day and let you know what route I took.

Mart.
 
Mart, I asked Mac this same question some time ago and got the same answer, so when I had two cases that were wasted on the faces as you have, I just found a good case and rebuilt it. By the way those two cases went to the scrap man three days ago. Did I cringe at scrapping them? You bet I did,,,,,,but. :eek:
 
I think with a long milling cutter you could reach down and machine it ,its setting it up square would take some time Ted
 
I have used thin hardened steel thrust washers against rough cast surfaces as such and then add an original thrust surface in a trans and it held up. Pictures might help.
 
I'm not a machinist by any stretch of the imagination, but I have a hard time believing there is not some type of cost effective way to machine that inner surface and then make a shim washer the same thickness of the material that was removed.
Even if it can't be done inexpensively, if someone wants to retain the original transmission case, with the serial number that matches the frame, it may be worth the cost to them..
 
I made a fixture to fit in my milling machine to go thru the front hole and then attached a boring cutter to reface the surface and added shims to make up the difference. It can be done, just takes some thought and patience.
 
Mart,
To satisfy a cost is no object customer maybe 10 years ago I fabbed an arbor
that piloted thru both the front and rear cluster shaft bores. Using a large dia spot facer with a .750 bore attached to the arbor I was able to clean up the disastrous
rear face on a # match case. Now don't chuckle too much but to 'replace' the metal
machined off I made a proper thickness steel spacer with a small knob protruding
on one face. This knob registered into the cast in oil pocket to intentionally keep the spacer from rotating. The final step was an application of DEV CON epoxy between the case and spacer......It works........the trans in my truck has this repair as well with no issues in a few billion revs. The oil grooves in the rear thrust washer were deepened
and a groove added just to be sure. The copper/babbitt bearing material on the washer is happier running against smooth steel than iron in my estimation.
Not cheap.
Charlie ny
 
some more late night thoughts about hillbilly machine work... i would turn an arbor on the lathe, i know you have one, that fits the bore in the case, then turn one one end down and thread it to the size of a valve grinding stone, and use the back side of the stone to cut, and make a brass bushing to get back to the case size on the stone end. drive it with a drill. you are just trying to make it square with the case, and then shim back to the desired endplay for the shaft. piece o cake
 
You must log in or register to reply here.
Back
Top