Transmission theory 101

[cas3]

Get comfortable...I'm rebuilding the trans/transfercase in my 52 willys jeep. The 3 speed trans is pretty much the same thing as our old fords, and even shares the same "jump out of 2nd gear" symptoms we fight. My unit was in very bad shape. Not so much wore out, but lots of rust damage, it must have sat for a long time, condensation and occasional use killed it. Now, almost everything is new inside, should stay in 2nd gear. A trick I learned from the jeep guys is, once its all together put the shift tower on, click it into 2nd gear, and remove the cover to see how much the syncro sleeve is covering the cheverons on the gear. In the photo, I placed a feeler gauge in that space to help illustrate the space i'm referring to. There is no spec I'm aware of, just that they say you want to darn near touch the gear with the sleeve, and if not, the start to shim the back of the main shaft to push it forward. I get to that point, sleeve covers the chevrons, but lots of space left. In this case, input shaft is new, 2nd gear is new, bearings are new, and blocker rings are new. So, I doubt I could shim the back, or the blocker rings would start to drag too much. Well, good idea, but I figure my new parts will suffice. Next, when I go to rebuild the top cover, I see that the fork is loose on the rail. As you can see in the photo, dial indicator set up shows .030 wobble front to back, and pin is finger tight. Take it apart, and the rail shows zero wear, so I figure the fork is worn out. Luckily, Midwest Military is 25 miles away, so off I go for a new fork. First, we look thru a bin full of used forks and shafts, all loose. next we dig thru a pile of used assembly's, all loose, next he hands me an NOS top cover all wrapped in cosmolene, 50 bucks...ok, back home I go. Next, I wash it all off, and once its clean...ITS LOOSE ! Check with indicator, its got .020 wobble front to back. Now, I am no trans expert, but in the dozen or so I have rebuilt, I have never seen those forks loose on the rail. Usually takes a brass hammer to get them off. Next I go out to the barn and look at a bunch of ford towers, they are all tight, zero wobble. I can't believe willys thought that is ok, but it seems they do. Next, for an experiment, I take an extra fork and heat it red hot, dunk it in the snow bank to try and shrink it. It took 3 times, but I now have it snug on the shaft. So, before I proceed on with the NOS fork, what do you guys think? Am I making the fork weak? It seems to not even be discolored past the base, so the fork ends should still be hard I presume. I also tried using a roll pin, that did snug it up quite a bit, but not really proper use of a roll pin, and how long would it last. Any thoughts ?

[mercman from oz]

Transmission Rebuild - cas3

[Tinker]

Willys jeep has always been in my bucket list. Feeling comfy.

[Brian]

Cas, I like your novel use of quenching in a snow drift...should work a treat. I have used roll pins to locate the forks in my 35 for about the last 40 years with zero issues.

[cas3]

For Tinker, here's a pic of when I bought it last May. Spotless clean. The story is, they bought it in 1984. "Dad was a vet, and wanted an Army Jeep". Then the usual story, "Dad drove it all the time". Then, "well, it hasn't ran since last fall, but should start".
Included was a letter from the PO stating it was just painted, had a new top, and tires, again, in 1984. Well, the vinyl top looked new. No faded plastic windows, spotless clean, never spent a day in the sun. Nearly 40 years old, and I sold it for 300 bucks to a happy customer. On a Jeep, the Tie rod is in front of the axle. This one, had a big bend in it, like 3" or so, like they hit a stump, and the fresh green paint was undisturbed, so I assume it was bent the whole 40 years they owned it. Front tires bald, rears like new. "dad drove it all the time" , yeah, rite. It was very hard to get started the first day I played with it, but once I had a few miles on it came to life. The army overhauled the motor in 57, and I dont think it has seen much use since. Now, after about 2k miles last summer it shows 118-120 compression on all 4, so she's healthy. It is really a good original, never been crashed or rust repair, even has nice OD green on the bottom of the floor. Too bad they painted it, I imagine it was quite original in 1984. It is still all original under the hood, 24 volt and all its fording lines intact in case I want to go swimming. This is the devil that I broke my leg last summer changing the 1951 dated 6 ply tires on. So, in summary, they had just started to wreck it, and I plan to put it back to an Army Jeep. Got a few holes to weld up from the roll bar and vinyl top, and I will then have a very nice 1952 M38 Willys. One of the last, # 56500 out of 60k made. It'll be OD green when the snow melts. 1st pic the day I bought it, next, an old guy in bad need of a haircut with a broken leg last summer

[cas3]

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Thanks Brian, I always respect your input

[Tinker]

Fin' hippie. haha My hair is beyond my neck line now. Always had it cut short. Glad I still have it. So no judgement here or before. Hope your pops leg heals well.


Great story and great jeep. Look forward to further posts.

[cas3]

Well, usually I look a lot like a movie star, but I had just driven 30 miles in the Jeep when the paparatsi took that photo

[cas3]

For fun, I have to add, I dont think it had been run in many years. First day, I topped off all the fluids...all were very low. Short drive around the block, 4 miles, and parked it in the garage for the night. Next morning it looked like I was making pan cakes on the floor. 1/4" thick 6" puddles of brown goo on the floor. When I drained the gearboxes for the rebuild it looked like butterscotch pudding

[Tim Ayers]

I learned to drive @ 12 years old on my dad's Willys CJ2A. What a fun vehicle. Good luck on the rebuild.

[Marcus]

CAS3 ~ You may already be aware, but may I suggest you get to know Mike at Kaiser~Willys: Mike is my go~to guy for all things Jeep related. I had 8 Willys at one time, now have downsized to just a 1942, totally restored. Mike furnishes a complete catalog that includes substantial drawings and specifications and will gladly answer questions.
I agree with Brian: roll pins are quick and easy, never had a problem.
Enjoy your M38: Mike has the brackets, hard~to~find proper shovel and axe if you wish to add the pioneer tools.

[cas3]

Well I now have the only jeep on the planet with tight shift forks. It took two times of heat / and ice to shrink about .004 to get a light "hammer on" fit. Topped off with a roll pin safety wired on. Its even had oil in it for 24 hours and none is on the floor!! Well, yet anyway. Now Marcus, yes I am aware of Kaiser Willys, lots of parts there. It is amazing how much NOS stuff is still around for these old jeeps. I am fortunate to be near Midwest Military, a specialist in jeeps and WW2 Dodges. I am looking for a m38 gas tank if you have too many, this one has a new tank, but it is a cheap generic thing that holds less gas, and does not make me happy. Would prefer the real deal, thanks