I am about ready to start ( once again) working on an old project, my 1955 Chevy 210. It has a 1969 350 truck engine with what we used to call a 3/4 race cam and it HAD a 4 speed Hurst hooked to a 4 speed munci tranny. However some years back some one helped them selves to the tranny and the shifter. I am now looking for a 4 speed munci or a suggestion for a replacement. (PLEASE DO NOT SUGGEST AN AUTOMATIC) That would be worse then 3.2 beer and a new wedding ring
I know that the T5 5-speeds are popular and somewhat more available then a Muncie 4-speed. I'd bite the bullet and get another M21 and either get a rebuilt one or go through it yourself, spring for a new quality shifter and be done with it forever. Bob
I would stick with the muncie and hurst both are easy to find. Be sure to get the later muncie with the 1 inch cluster shaft. If you want new try the Richmond in either 4 or 5 speed.
The M20 was the smaller cluster gear shaft, 3/4" I think. The M22 was the "rock-crusher", so named because of the straighter cut on the gears and the resultant noise they made, although most would call it music!
Oh , stone crusher I get it , Ive been looking at this thread all day trying to figure out what the hell he was trying to say.
the borg warner t-10's were the same thing too. available up to '81 in the z28 camaro. shouldnt be too hard to find one of them.
A cheaper alternative to the Muncie or any other 4 speed is a Muncie 3 speed from a 1/2 ton pickup. You can find them for $75-$150 and they're quite strong.
I found my Borg Warner Super T-10 on ebay for $400. It came out of a Camaro, had the 2:88 first gear ratio I wanted and was in good shape. You can still buy the tranny new from Richmond I think, and the Super T-10 offers better 1st gear ratios IMO for Drag Racing if thats your thing.
The lower the first gear, the less torque the tranny will take before it explodes. M-21 (2.20 first) is a close ratio, m-20 is a wide ratio (2:52 first) rock crusher had gears cut straighter. I believe rocks were all 2.20:1 from GM. There a tons of aftermarket parts for these.
I thought it was the other way around.M20's had 2.56 low and M21's and M22's had 2.20 low.I could be wrong and most of the time i am ,but i thought the M20 was a small block trans and the lower first gear was to make up for the lack of low end torque versus a Big Block ...
A super T-10 or a muncie. I saw a recent post with a M-21 for $575.........I think. There's a guy around town here that gets over a $1000 out a rebuilds M-20 and 21s, $1400 for a M-22.
ALL Muncie 4 speeds were upgraded to the larger countergear shaft about mid 1968, but unless you plan on high RPM clutch drops with sticky tires it's probably a moot point. About the same time they started using bolts to mount the shift arms to the side case instead of studs and nuts. Not a foolproof ID, but fairly reliable when an original transmission is in a car. Of greater importance on a transmission with high mileage or abuse is the fact that the countergear shaft bore is unbushed and the countergear shaft causes the aluminum case to egg out over time misaligning the counter gear. Wide ratio (M20) Muncies are usually listed as having a 2.52 or 2.56 low gear and need to be used with a 3.31, 3.42, or 3.55 rear gear (as usually supplied by the factory) for optimum street operation. Close ratio (M21 or M22) Muncies have a 2.20 low gear originally designed to be used in road racing Corvettes. As a result they could commonly found with 3.31, 3.55, 3.73, 4.11, or 4.56 rear end ratios, although most street cars would carry 3.73 and 4.11 ratios. Drag racers found out early on that using a VERY steep rear end gear ratio (at least 4.11, but not unusual with 4.56, 4.88, or 5.13 if the engine would rev high enough at the finish line) with the transmission ratios closer together resulted in lower elapsed times. If you need or want more detailed info, a good place to start is the HAMB search button, as there have been many Muncie threads posted.
I have put togther a bunch of Muncies. I currently have about 14 cores which I build on request- The M20 is a wide ratio box, the M21 a close ratio box. The M22 does indeed have straighter cut gears hence the term rock crusher. '65 and pre 65 cases have a 7/8 inch counter shaft, post 65 a 1 inch counter shaft. Casting numbers ending in "325" are the 7/8 shaft, cases ending in "010", "660" "661" are the 1 inch counter shafts- the casting numbers translate as follows: 010- 1966-67 660-1968-69 661 - 1970-73 There are 10 spline course input shafts through about 1970 and then fine spline inputs after. The last 1970-73 cases have two drain plugs though I am told there are two plugs on the early cases used for the M22s. BTW all the gears are the same except for the input shaft and cluster gear-these are matched to designation of M20, 21 or 22 and these give you your overall gearing. This is from memory but should be generally accurate. For a 1969 case with new bearings, gaskets, syncros, washers, hand cleaned case, new hardware etc- I typically would ask for about $950. I do them locally on request. Chevy by the Numbers will translate casting numbers, and the web sources will give you an idea as to gearing ratios.
I have a variety of them here and they're great transmissions. I have one with a great 1st gear that works nicely in heavy cars. Bob
more Muncie info: Year 1963-1965 Type: M20 Ratio: 2.56 / 1.91 / 1.48 / 1.00 Year 1966-1974 Type: M20 Ratio: 2.52 / 1.88 / 1.46 / 1.00 Year 1963-1974 Type: M21 Ratio: 2.20 / 1.64 / 1.28 / 1.00 Year 1967-1974 Type: M22 Ratio: 2.20 / 1.64 / 1.28 / 1.00 M20-M21 have a 30* gear angle M-22 has a 20* gear angle input shaft tooth & spline count by years Year 1963-1965 Type: M20 -- Rings: None -- Spline: 10 Tooth Count: 24 Year 1966-1970 Type: M20 -- Rings: Two -- Spline: 10 Tooth Count: 21 Year 1970-1974 Type: M20 -- Rings: Two -- Spline: 26 Tooth Count: 21 Year 1963-1970 Type: M21 -- Rings: One -- Spline: 10 Tooth Count: 26 Year 1970-1974 Type: M21 -- Rings: One -- Spline: 26 Tooth Count: 26 Year 1967-1970 Type: M22 -- Rings: None -- Spline: 10 Tooth Count: 26 Year 1969-1974 Type: M22 -- Rings: None -- Spline: 26 Tooth Count: 26 serial & vin numbers serial numbers begin with the letter "P" for Muncie plant serial numbers 1963 to 1966 included only the month and day. P0101 would indicate January 1st. 1967 to 1968 the number got a year designation & a letter designation for the month such as P8A01, meaning January 1st 1968. 1969 to 1974 Muncies got a ratio designation at the end of the serial number. An example would be P4D23B. This equates to April 23, 1974, M21 ratio. month code January Letter: A February Letter: B March Letter: C April Letter: D May Letter: E June Letter: H July Letter: K August Letter: M September Letter: P October Letter: R November Letter: S December Letter: T ratio codes for 1969-1974 Letter: A M20 Ratio Letter: B M21 Ratio Letter: C M22 Ratio case casting numbers, related to production years & ratiosCast:3831704 Year:1963 Only Ratio:M20 2.56 1st ,M21 2.20 1st Cast:3851325 Year:1964-1965 Ratio:M20 2.56 1st ,M21 2.20 1st Cast:3885010 Year:1965-1967 Ratio:M20 2.52 1st ,M21&M22 2.20 1st Cast:3925660 Year:1968-1970 Ratio:M20 2.52 1st ,M21&M22 2.20 1st Cast:3925661 Year:1970-1974 Ratio:M20 2.52 1st ,M21&M22 2.20 1st
A buddy of mine is trying to sell a m-22 rock crusher (dated '71) he just had it freshened up. Pm me if you interested and i'll pass on his contact number. Paul
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