Factory C3 manual transmissions
#1
Factory C3 manual transmissions
Does anyone know what manual transmissions were offered from the factory for the later C3s? I am looking at a manual conversion kit offered from a Corvette salvage yard, but I am not sure what I may be getting. Thanks.
#2
Melting Slicks
My 76 has the borge warner T10, I know it's not a later C3 but I think that the earlier ones had the muncie so maybe GM stuck with the BW t10, in any case I would think either one would work for you. I have to wonder why if you are going to manual you just don't go with a 5 or 6 speed.
#3
I believe up to 73 was the Muncie, after 73 it was Borg-Warner. Don't know much about the BW, but Muncies have both case numbers and tail shaft numbers that you need to make a car period correct. I know the 73 has a fine 26 spline input shaft, earlier ones have a 10 spline.
#4
Le Mans Master
later C3's have the Borg Warner Super T10...
I'm putting one in my '73, the '73 would come with a Muncie stock, but the Super T10 will bolt right in.
I'm putting one in my '73, the '73 would come with a Muncie stock, but the Super T10 will bolt right in.
#5
Safety Car
PT
Looks like you've got an 81 and as others state the Borg Warner was used, for the most part in late model C3s. The link below is to an article that describes in greater detail B/W and also the Saginaws (Muncies) used during the later years. The article also references casting numbers and you should be able to sync up these references to any B/W four-speed. And you do want to stick with the B/W...avoid the later year Muncies that are a cast iron case...parts difficult to get.
Good luck and hope this helps.
Four speeds
Looks like you've got an 81 and as others state the Borg Warner was used, for the most part in late model C3s. The link below is to an article that describes in greater detail B/W and also the Saginaws (Muncies) used during the later years. The article also references casting numbers and you should be able to sync up these references to any B/W four-speed. And you do want to stick with the B/W...avoid the later year Muncies that are a cast iron case...parts difficult to get.
Good luck and hope this helps.
Four speeds
#6
Muncies with around 2.6 (wide ratio) or 2.2 close ratio) were offered up to 73. The BW T10 was offered after that, typically with a 2.6 1st. Around 1980, the corvettes got a 3.08-2.73 rear end ratio, probably for gas milage/emmisions. Those cars got a T10 with a 2.88 1st gear to work better with the lower numeric rear end.
If you've got an 81 with a relatively stock engine, try to find a 2.88 1st gear T10 to get good acceleration out of the hole.
The super T10s are still offered by Richmond Gear, but later T10s (1" countershaft) are pretty strong transmissions and all parts are still available.
Here's a directory with info on identifying the T10.
http://www.pontiacpower.org/BW.htm
If you've got an 81 with a relatively stock engine, try to find a 2.88 1st gear T10 to get good acceleration out of the hole.
The super T10s are still offered by Richmond Gear, but later T10s (1" countershaft) are pretty strong transmissions and all parts are still available.
Here's a directory with info on identifying the T10.
http://www.pontiacpower.org/BW.htm
#8
#9
Drifting
1980 specs
BW Super T10
(MM4) 4-Speed Manual
Gear Ratios
1st 2.88
2nd 1.91
3rd 1.33
4th 1.00
Reverse NA
Axle Ratio 307:1
I sold my stock 4 speed setup out of my 80' and installed a T56 6speed, converted to a hydraulic clutch, and replaced the rear with 370 gears. Good luck with your conversion.
BW Super T10
(MM4) 4-Speed Manual
Gear Ratios
1st 2.88
2nd 1.91
3rd 1.33
4th 1.00
Reverse NA
Axle Ratio 307:1
I sold my stock 4 speed setup out of my 80' and installed a T56 6speed, converted to a hydraulic clutch, and replaced the rear with 370 gears. Good luck with your conversion.
#10
OK, OK...73 or 74 seems to be the changeover.
But the T10 and Muncie design for around those years was almost an identical design (with the exception of the side cover interlock mechanism). If that's the year of the OP year, either will work. I'm actually running a combo of Muncie and Hurst shifter parts on a T10 now.
There are some other year to year differences like the th350 vs th400 style output yoke, but nothing that would prohibit using one over the other.
I think the rear end ratio and engine should be the deciding factor on what trans to use.
But the T10 and Muncie design for around those years was almost an identical design (with the exception of the side cover interlock mechanism). If that's the year of the OP year, either will work. I'm actually running a combo of Muncie and Hurst shifter parts on a T10 now.
There are some other year to year differences like the th350 vs th400 style output yoke, but nothing that would prohibit using one over the other.
I think the rear end ratio and engine should be the deciding factor on what trans to use.
#12
Race Director
You have to have the correct number of input splines 10 or 26 otherwise it won't work. Other than that the C3 specific Super T10's had a lower first gear than the Muncies usually a 2.88. This is not written in stone
#13
Thanks to all. I have not made any decisions yet, and just trying to get all the info I can. I have considered the 5 speed option., and have been reading all the posts and articles I can fine. I believe the overdrive would be great for cruising. I am not concerned with keeping the car stock, I am building a toy to replace my dirt track car.
#14
If you have a 2.73 or 3.08 rear, you'll be restricted in the OD ratios. Most are in the 0.6 something range for OD. That would put your cruising rpm very low for a small block. The Richmond 6 speed is offered with a 0.76 OD that would work with a 3.08 but might be a bit much for 2.73/ The TKO is also available in a 0.8 OD but has a fairly high 1st gear.
Just a quick calculation. A TKO with 0.64OD on a 2.73 rear will put you under 1600rpm at 70mph. That might work for a 6.0 LS2 but would be useless for a big cam small block.
Also check the available rear end raios for your year. Early iron case diffs have a huge range of ring/pinions. Later aluminum case diffs can be limited in availability. The cost to change a C3 rear is also relatively expensive.
Just a quick calculation. A TKO with 0.64OD on a 2.73 rear will put you under 1600rpm at 70mph. That might work for a 6.0 LS2 but would be useless for a big cam small block.
Also check the available rear end raios for your year. Early iron case diffs have a huge range of ring/pinions. Later aluminum case diffs can be limited in availability. The cost to change a C3 rear is also relatively expensive.
Last edited by Garys 68; 11-19-2012 at 12:03 PM.
#16
Race Director
Muncies were used through 1974. Borg-Warner Super T-10's were used from 75-81, though some 78-79 Corvettes got Saginaw 4 speeds (mainly with L-48's).
Both close ratio and wide ratio versions of the Muncie and 75-79 Borg-Warner's were offered. The Saginaw's were all wide ratios, as were the 80-81 Super T-10's.
Federal emission 81 automatic cars, all came with a 2:87 rear axle ratio. California Emission automatics came with a 2:72 axle, but were available with the 2:87 as a "Performance" option. Both Federal and California emission 81 4 speed cars, only came with a 2:72 rear.
I agree with Garys 68, that because of the low numerical rear end, you'll really want to find a trans with a shorter first gear, such as the 2:88.
The M-20 dose not indicate that the trans is a Muncie. M-20 was just Chevrolet's ordering code (RPO), for a 4 speed wide ratio transmission. It did not indicate the manufacturer of the trans.
Chevrolet continued to use the M-20 and M-21 RPO, through 1978, even though they were all either Borg-Warner and Saginaw transmissions.
To Chevrolet, M-20 was a wide ratio 4 speed trans, M-21 was a close ratio 4 speed, and M-22 was a heavy-duty 4 speed. This goes all the way back to 1963, when Chevrolet first started using the letter/numeral RPO ordering codes. 63's built prior to May 1963, had Borg-Warner T-10's, while Muncies were used starting in early May. Both transmissions carried RPO M-20.
Both close ratio and wide ratio versions of the Muncie and 75-79 Borg-Warner's were offered. The Saginaw's were all wide ratios, as were the 80-81 Super T-10's.
Federal emission 81 automatic cars, all came with a 2:87 rear axle ratio. California Emission automatics came with a 2:72 axle, but were available with the 2:87 as a "Performance" option. Both Federal and California emission 81 4 speed cars, only came with a 2:72 rear.
I agree with Garys 68, that because of the low numerical rear end, you'll really want to find a trans with a shorter first gear, such as the 2:88.
Chevrolet continued to use the M-20 and M-21 RPO, through 1978, even though they were all either Borg-Warner and Saginaw transmissions.
To Chevrolet, M-20 was a wide ratio 4 speed trans, M-21 was a close ratio 4 speed, and M-22 was a heavy-duty 4 speed. This goes all the way back to 1963, when Chevrolet first started using the letter/numeral RPO ordering codes. 63's built prior to May 1963, had Borg-Warner T-10's, while Muncies were used starting in early May. Both transmissions carried RPO M-20.