Synchro going on 4th gear in my Muncie due to 4:11�s

[Jim D.]

[Joe L.]

[Richard G.]

[Gary R.]

[Joe L.]

Joe
when did the iron plate go away? I have used them several times I really liked the fit and the added strength

Gary-------


I only found out about this recently and I think it was discontinued fairly recently but I'm not sure. They claim that the current aluminum plate is an "improved" version. I don't know why the ductile iron plate was discontinued. I liked it, too. It added strength for only a slight difference in overall transmission weight. I built my M-22 with all NOS parts except for the fact I used the ductile iron plate (even though I have NOS examples of the original plate).

[Gary R.]

[Ronald L.]

[Steven B.]

[Joe L.]

Joe = what year M-22 did you build?

Ronald------


It's basically a 1969-70 but differs very little from a 1966-68.

[Gary C.]

[Gary C.]

[Joe L.]

[Gary C.]

[Joe L.]

I now know what parts I require and I'll try GM. Autogear.

Cluster R27-22-19-17T:M21
Maindrive L26-S36T M21 10 Spline
Shift Fork
Idler Gear Rear L18-s27T
Now that wont be too expensive, especially with shipping to Australia!

Gary------


I'm still not so sure that you need to replace all these parts. The cluster gear looks OK to me. Even if there's a little wear on the teeth I think it will work OK for as long as you're going to need it to do so. Certainly, any wear on this gear would have nothing to do with a shifting problem.

The input gear does have some wear on the synchro teeth but I've seen a LOT worse.

The reverse idler gear does have significant wear on the teeth. However, as I mentioned, this is not a constant mesh gear and there's often wear where the teeth clash. Once again, although worn I think it will last as long as you are going to need it to do so. Most folks don't really spend that much time in reverse.

As far as a source for the parts, forget GM. All the Muncie parts are long-since GM-discontinued. One of the last available parts was the shifter forks and even these have been gone a long while now. You could look for NOS. Here are the part numbers:

cluster gear------originally GM #3864858, later GM #3905465, last available as GM #357236

reverse idler gear (front)-----originally GM #3831764, last available as GM #356231

input gear-----originally GM #3831766, later GM #3925690 last available as GM #357242

shifter forks----3831717

As far as NOS goes, you'll be extremely lucky to even find the last available GM part numbers. The supply of OEM Muncie gears pretty much dried up years ago before there were aftermarket replacements and when folks with Mucies needed replacement gears. Most, if not all, of the aftermarket replacements are manufactured by Masiero S.A., the Italian manufacturer that's one of the largest manufacturers of gears in the world.

[Gary C.]