Looking for a little help from the M21 Muncie guru’s. The M21 Muncie 4-speed in my ’65 C10 has a broken reverse shift stud. Is it possible to drill and tap the reverse shaft or is it a hardened part?: (1963-1965 vintage M21: Main case 3851325, Tail Housing 3846429, Side Cover 3831707) I have a spare M-21 which is a newer vintage M21 (‘68-’70). I bought it about 15 years ago, don’t know much about its history. Funny thing is it also has the side stud style shift arms, except for reverse, which has a bolt in it. Does this seem "factory correct" or is this more likely to be a modification from a previous owner ? (68-70 vintage M21: Main case 3925660, Tail Housing 3857584, Side Cover 3950306)
I'd hate to try to drill that straight free hand but that may because I've proven more than once I can't seem to drill a straight hole freehand. if you have it out it shouldn't be that hard to pull the tail shaft off and pull that piece out and take it to a machine shop where they can drill it straight and square and tap it for a stud. On that trans it would be worth spending the money to do that.
Punch davids 4 speeds in your computer. Get a new part and the gskts and seals and fix it. He is a great guy and will do what he says ( he is local to me ) . Gary
They changed from the stud type to a bolt thru type for '69. The shifter arms are different for each style try one of the muncie vendors for the new cam lever. I have had good luck with both Dave mentioned above and Manchester Muncies in Iowa.
I have fixed one of mine by drilling and using a bolt like you said,, It's not rocket science by any means.Grind the broken stud flat, drill a small pilot hole straight as you can, then step up the drill size one at a time until you get what you need,tap it use some lock tite on the bolt and your good to go.
I am being told the part is "harder than hammered owl shit".. sounds pretty hard, eh? The one that you drilled and tapped, was it hardened steel or just plain ole steel bar stock? Thanks.
Don't know how hard hammered Owl Shit is,,Not into that stuff really, but yes i am sure it is a hardened shaft,, That is why they make carbide & titanium drill bits, I used carbide on mine since i have a full set. It is not a big deal to change the fork either, It was quicker for me to drill and tap, it is still on the car and did it ten years ago.
Drilling is one thing to deal with now tapping a hole will not be an easy task. A normal tap isn't go to cut it.Source a replacement and be done with it.You will spend more time and money buying tooling than a replacement costs. T
Drilled and tapped the shaft today, drilled pretty easy, tapping was a bit unnerving, but successful nonetheless. Thanks for the help.
Good looking fix. I especially like the stud and nut. (a bolt is just asking for it!) The secure installation of a stud (with some Loctite) and the stud will be as one with the shaft.
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