Muncie M20 Paperweight

[robertsjm711]

Tore down my 1965 M20 this last weekend to find parts not where I left them when I put it together last winter. It was jumping out of third and had a squeeky sound. The sound I wasn't so concerned about but should have...

Spun the counter-shaft thrust bearing and it has a crack from the reverse hole to the main hole. I think I can rebuild it for ~$6-700 unless I can find one used (and not in the same condition)

Anyone have any first hand experience and the outcome? Maybe recommended parts to replace (other than case & mid-plate for obvious reasons)?

[YoungPup1977]

Look around on the internet you should be able to find a “325” casting which has the 7/8 main shaft. Muncie is one of the easiest trans to rebuild and several people build them and have cases available

I have several Muncie transmissions already built but no cases to sell.
Good luck !

[Tom]

Muncie supercase.
My M20 case is worn out and allowed too much shaft play, killing the new rebuild in like 3000 miles. The only real choice is the supercase. https://www.5speeds.com/case.html

[Indian113]

I found a main case - casting #325 on facebook marketplace in Sioux Falls SD.

[YoungPup1977]

Originally Posted by Tom

Muncie supercase.
My M20 case is worn out and allowed too much shaft play, killing the new rebuild in like 3000 miles. The only real choice is the supercase. https://www.5speeds.com/case.html

Supercase is good stuff but I don’t agree with being the only option. Did you rebuild yours and overlooked the end play. End play issues can be fixed plus it’s different from the case being worn out and cracked.

[robertsjm711]

Yes, I overlooked the end play and it is now cracked. It leaked out the counter shaft pin, so it needs replaced.

[Tom]

Originally Posted by YoungPup1977

Supercase is good stuff but I don’t agree with being the only option. Did you rebuild yours and overlooked the end play. End play issues can be fixed plus it’s different from the case being worn out and cracked.

A shop rebuilt mine and overlooked it yes. The large hole in the front of the case is worn out. The previous case had the same problem. They found a new used case for me and rebuilt it. They obviously suck lol.

[YoungPup1977]

I fix Muncie cases all the time, cracked, worn input bearing areas, reverse idler gear area.... aluminum can be worked. When you have a original Muncie 4 speed in a 69 Camaro its hard to just toss the case that is stamped with the original VIN on the trans case.
I do understand here in this forum most do not care about original numbers and/or numbers matching scenarios. toss it and get another approach works for you. take it to Joe's down the street to Cob job a T10/saginaw in replacing the Muncie