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I'm going to look at a used Muncie later today, from the one picture I've seen it has an M20 input shaft.
I want a wide ratio trans for my car, so I'll be sure it has the correct gear ratio to go with that input shaft.
While searching here this morning I've discovered that the case can stretch.
Other than checking counter shaft end play I can't think of a good way to determine if this trans has a stretched case.
How likely is that to be a problem, and what other problem areas should I try to check when I'm looking at this trans?
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
the hole around the idler shaft can wobble out or stretch as you say. it will leak around that shaft and the only way to get it fixed is have the case reamed and shimmed. If you go to the gear box videos on you tube you will lean a lot. Paul fixes those. THe early cases use a 7/8 inch shaft and the later ones use a 1 inch shaft. If you have and M21 you can convert it to a M20 by changing the input shaft and the idler gear. Checking inventory, unfortunately most gears are sold out.
Thanks.
When I read of case stretch I originally thought length wise, as the bevel in the gears forced the shafts to each end of the case.
Height wise makes more sense, as the gears force themselves apart.
Be sure to pull the side cover and look at the engagement teeth and gears for broken teeth or pitting. There's a lot of Muncies out there but the last one installed new in a vette was 1974 so you have to look close or you may get junk. Ask if it's ever been apart, look close at the cluster gear bore in the case for any oil stains. There were different slip yokes used most of the early ones were 1310, your driveshaft should be 1330. A super T10 may work better for a street car, better first gear in 1st.
And it wasn't a Muncie, it's a Saginaw. I was basing my ID on one pic on Craigslist, it had a fresh coat of silver paint over cast iron.
The gears looked good and the synchros looked great, it has the 3.11 first gear, a Hurst shifter and a bell housing so I bought it.
The 3.11 first will work great with my 3.08 diff, so I won't have to re-gear that.
I had priced a 5 speed swap kit a few months ago but have since gotten cold feet about spending that much money on this car.
I'll do a cheep 4 speed swap, and if I like it spend more money on a better trans later.
I'd like to know if I can use a factory length driveshaft with this Saginaw in my car.
I've found two sources that state they are the same length, I'd rather verify with a tape measure for myself.
One of the sources also stated that my TH350 output yoke will fit the trans I picked up. I'll check that for myself when I get the car up in the air.
Used Muncie Transmission
