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 ?