Wanted: Muncie M20 and accessories

[ykf7b0]

I am looking to buy an Muncie M20 with bellhousing for a small block Chevy, the shifter mechanism, and a shifter for a bench seat.

[BamaNomad]

I have several '403' bell housings, if you're close enough to North Alabama to come look thru them...?

[ykf7b0]

Thanks Bama! If I don't come up with something I will give you a holler. I'm about 100 miles from Florence.

[ykf7b0]

I am looking to buy an Muncie M20 with bellhousing for a small block Chevy, the shifter mechanism, and a shifter for a bench seat.

After further study, I think the M21 would be a better choice because I have 3.70 rear gearing. Sorry

[markm]

BW Super T10 have a wider variety of gear ratios so don't over look them.

[Rick_L]

M21 is never a good choice for anything but road racing.

[ykf7b0]

M21 is never a good choice for anything but road racing.

Explain please. The only information I have is that with a low rear gear (3.70) the M21 is a better choice than the M20 but the author of that post could be mistaken I suppose.

[BamaNomad]

Bo: What Rick was stating is true. The M21 is a 'close ratio' transmission which is designed for situations where there is no demand for a wide range of vehicle speeds, ie. racing where the engine speed and the vehicle speed tends to be in a small range at the TOP of the curve. The 3.70:1 ratio rear you have is just into the range where a close ratio trans might be the right choice IF you plan to do 'spirited street driving'.. ie. racing from light to light, etc. For a Cruiser planned to operate at several driving situations, it's not the best choice.

For street driving, you are stop/go and slow speeds along with higher speeds on the highway, and having a transmission with a wider range of ratios is beneficial. In the modern case, multiple speeds (5 or 6 speeds or even more with auto trans) provides a very wide range of ratios which allows the engine to operate efficiently at any/all vehicle speeds. If I planned to operate with a 3.70:1 rear ratio for a 'cruiser' street machine, then I'd want to go to an OD transmission... even the factory 3 spd OD unit would be better than a standard 4-speed in many of those situations IMO.

I have a '69 Z28 with 3.73 rear and a wide ratio Muncie, and it is barely able to accelerate from a stop without revving up to near 3000 rpm. The M20 Wide ratio first gear is 2:56:1, whereas the M21 close ratio trans has a 2.20:1 ratio first gear. Both have 1:1 final drive ratios.

[55 Rescue Dog]

When I first got my 2900lb Camaro on the road with a M21 in it, I too didn't really like the 2.20 first gear for off the line acceleration. Having a light flywheel didn't help, and I am running a 4.47 gear in the quick-change rear. The tranny had to come back out for another issue, but when it was getting gone through again, I had the gears changed to the wide-ration gear set, and it is so much better for street driving.
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[ykf7b0]

Thank you both for setting me straight on this! I know a five or six speed would be a much better choice but it will cost me more than double. I’m thinking I can go with an M20 and later when I’m able I can change the rear gear ratio.