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Hello; Can someone tell me if it is possible to have ordered a M20 wide ratio 4 speed trans in a 1963 FI coupe with a 3:36 Posi rear. I have been told that M20's were used in all 250 and 300 HP 1963 corvettes and the M21 CLOSE ratio was used in all 340 and 360 HP cars. On the other hand I have been told that if you had a 3:08 or a 3:36 rear the Wide ratio trans was used and if the rear was a 3:70 or a 4:11 or a 4:56 ratio the Close ratio trans was used? If you can help, please do and Happy Holidays! andy
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Re: 1963 muncie transmission
The optional four-speed transmission was coded M-20 in 1963. There was no M-21 for that model year. (The WR/CR were not broken out to M-20/M-21 until 1966.)
The order could not specify WR or CR by any means. It was based on the engine choice.
All base 250 HP and 300 HP M-20 orders received the WR verison with a 3.36 open axle. Positration was an option. A 3.08 could also be ordered in either open or Positraction form.
All 340/360 HP engines ordered with M20 (a three speed was standard) got the CR version. The user could not override this and specify a WR. The standard axle with these engines and M-20 was 3.70 open, and Positraction was optional.
Five optional axle ratios for 340/360 HP engines from 3.08 to 4.56 were optional in Positraction form only. The optional 3.08 open axle RPO G-91, $2.20, was only available with M-20 and the 250/300 HP engines.
Duke -
Re: 1963 muncie transmission
The optional four-speed transmission was coded M-20 in 1963. There was no M-21 for that model year. (The WR/CR were not broken out to M-20/M-21 until 1966.)
The order could not specify WR or CR by any means. It was based on the engine choice.
All base 250 HP and 300 HP M-20 orders received the WR verison with a 3.36 open axle. Positration was an option. A 3.08 could also be ordered in either open or Positraction form.
All 340/360 HP engines ordered with M20 (a three speed was standard) got the CR version. The user could not override this and specify a WR. The standard axle with these engines and M-20 was 3.70 open, and Positraction was optional.
Five optional axle ratios for 340/360 HP engines from 3.08 to 4.56 were optional in Positraction form only. The optional 3.08 open axle RPO G-91, $2.20, was only available with M-20 and the 250/300 HP engines.
DukeComment
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Re: 1963 muncie transmission
According to the option sheet (MF Dobbins, '63-67 Corvette Fact Book), high vs. low ratio 4-speed transmissions were separated by engine configuration.
250/300 HP gave you a 2.54 1st gear ratio with your choice of 3.08 (std) or 3.36 (optional) rear end ratios.
340/360 HP equipped engines gave you a 2.20 1st gear ratio with your choice of of the full compliment of rear end ratios (3.08, 3.36, 3.55, 3.70, 4.11 or 4.56) with the 3.70 being standard.
I think any other configuration was 'possible' but required COPO authorization.Comment
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Re: 1963 muncie transmission
According to the option sheet (MF Dobbins, '63-67 Corvette Fact Book), high vs. low ratio 4-speed transmissions were separated by engine configuration.
250/300 HP gave you a 2.54 1st gear ratio with your choice of 3.08 (std) or 3.36 (optional) rear end ratios.
340/360 HP equipped engines gave you a 2.20 1st gear ratio with your choice of of the full compliment of rear end ratios (3.08, 3.36, 3.55, 3.70, 4.11 or 4.56) with the 3.70 being standard.
I think any other configuration was 'possible' but required COPO authorization.Comment
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Correction...
The low HP standard rear end was a 3.36 ratio with the 3.08 ratio being the option. Sorry about that. I made a transposition error when reciting the MF Dobbin power train option table...Comment
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Correction...
The low HP standard rear end was a 3.36 ratio with the 3.08 ratio being the option. Sorry about that. I made a transposition error when reciting the MF Dobbin power train option table...Comment
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.... and ? (2.56:1 on Muncie wide; 2.54 on BW) *NM*
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.... and ? (2.56:1 on Muncie wide; 2.54 on BW) *NM*
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