Deconstructing Tranny

Since it's now too warm to get any meaningful body work done, I figured I would do what I threatened and tear down the transmission. The Haynes manual is really quite descriptive as far as tear down and assembly in this case (usually, it's described as "assembly is the reverse of removal").

I've worked on every part of the Midget to date, except for the transmission. I can't say that any more!

First, I had to clean my workbench.

Then, I put a transmission on it.

Next, I removed the remote control housing.

After that, the side cover. There are a couple of selector plungers that came out with a little help from my air gun.

Next up was the clutch release fork and the front cover. The front cover had never been removed, I suspect. It was tough.

The reverse gear locating pin came next, followed by the selector forks and rods.

 

The manual says to measure the end float on the laygear (the one that doesn't have selectors and transmits power from the main shaft to the input shaft). This is cleverly done by moving the reverse gear out of the way and measuring the gap between the laygear and the back of the box. Mine measured out to 0.008", when it should be a max of 0.003".  So new thrust washers are needed. I'll have to figure out the right one, but they come in a range of sizes.

EDIT: After measuring with my vernier caliper, it looks like I'll need a .130" washer.

EDIT 2: After measuring the new front thrust washer, I need a .128 washer to bring the endfloat to 0.001" as recommended by many.  Fortunately, I bought one.  It will be close and I may have to do a little work to get things right.  I can always use the old front thrust washer--it's pretty good--but I'd rather replace it.

The most difficult part came next--removing the main shaft (or "third motion shaft"). It has a bearing and a whole bunch of gears on it held in place by a plate that press fits into the case. That was fun. Eventually I ended up clamping a grip wrench to the shaft and tapping on it to extract the plate. But it came out with no damage.

Last was the removal of the reverse gear, the laygear and the input shaft (first motion shaft). The last was easy--remove a retaining clip and lightly tap the shaft into the case, then remove the assembly.

I ended up with a completely stripped gearbox.  Result!

It looks like the main shaft bearing is ok, but I will replace it anyhow. The input shaft bearing is trashed. The roller bearing between the main and input shafts is pretty bad, too. However, everything else looks amazingly good. No debris or flakes in what was left of the fluid or coating the inside of the case. The gears look decent. The box worked well other than that vibration, so I think it will be better than ever when I'm done.

I ordered a rebuild kit from VB that has just about everything I need. I will have to order thrust washers from Moss, though, since it seems VB doesn't carry them.  What the heck. It's just another $250, right?  That pretty much taps me out.  Good thing I got a little birthday money to cover the gap.

Next time, I tear down the main shaft assembly. That should be fun. I'm a little nervous because if I get that wrong it's a real pain to set right, given I would have to remove the engine and gearbox to work on it. But it's just a machine. A working one, even. So I should be able to figure it out.