# Is it M6 or M12



## diverdan (Apr 27, 2005)

Why does everyone with a manual transmission refer to it as an M6? Mine came with an M12 (according to the plate under the hood and the build sheet in the trunk). I know that M6s came in C-5 Coupes and Verts while M12s came in the Z06. I know the M12 had lower gearing and (I think) was beefer is some ways, so I would think having an M12 is a good thing.
Am I missing something?


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## FoMoGo (Apr 22, 2005)

M6 = Manual 6 speed.
A4 = Automatic 4 speed.


Jim


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## diverdan (Apr 27, 2005)

FoMoGo said:


> M6 = Manual 6 speed.
> A4 = Automatic 4 speed.
> 
> 
> Jim


I'm familiar with that part.  
I was referring to the 2 different types of manual transmissions: the M6 and the M12.


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## FoMoGo (Apr 22, 2005)

diverdan said:


> I'm familiar with that part.
> I was referring to the 2 different types of manual transmissions: the M6 and the M12.


I know... but on every forum I am a member of... M6 and M12 as "names" never comes up... just the referance to the manual/auto.


Jim


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## GNX231 (Dec 12, 2004)

the vette trans while a 6 speed could never be used in any other car as it is in the rear of the vette so i think all the gto have only one trans they use unlike the vet. and zo6


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## x3ro (Jan 13, 2005)

diverdan said:


> I'm familiar with that part.
> I was referring to the 2 different types of manual transmissions: the M6 and the M12.


M12 is the code for the GTO and Zo6 manual tranny,

MN6 is the code for the C5 and fbody manual tranny..

most people say M6 just like a lot say M5 for a 5 speed manual, and A4 for a 4 speed auto

arty:


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## Subdriver (Dec 28, 2004)

x3ro said:


> M12 is the code for the GTO and Zo6 manual tranny,
> 
> MN6 is the code for the C5 and fbody manual tranny..
> 
> ...


 :agree (different gearing between M12 and MN6) :cheers


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## fergyflyer (Apr 18, 2005)

diverdan said:


> I'm familiar with that part.
> I was referring to the 2 different types of manual transmissions: the M6 and the M12.


Mn6 and m12 are two different transmissions.My 05 is an m12. Same tranny that is in the z06. They are two different versions of the Tremec T-56. The m12 has shorter 1-3 gears an equal 1to1 4th and shorter 5th and 6th. 

gear mn6 m12
1st 2.66 2.97
2nd 1.78 2.07
3rd 1.30 1.43
4th 1.00 1.00
5th .74 .84
6th .50 .57

A common misconception is that the Corvette 6 speed is a transaxle. The automatic is a transaxle, but the 6 speed is a seperate unit mounted in front of a differential. Our GTO's share the transmission and rear differential of the Corvette, with our cars having different half shafts. Our cars have the transmission mounted directly behind the engine, the Corvette has it mounted in the back. 
The T-56 Tremec was used by Ford for the supercharged Cobra, and is used by Dodge for the Viper and SRT-10 trucks. GM used it in the F-Bodies, and now uses it in the Corvette, GTO and CTS-V. 
It is basically unbreakable with less than 750 hp.
I just checked my 05 and it is an m12. The lower gears were probably selected to offset the weight.


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## diverdan (Apr 27, 2005)

From the responses, I'm gathering that everyone is just using M6 as a generic term and that all manual GTOs have M12s.

Thanks for the responses


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## Duck916 (Nov 12, 2004)

fergyflyer said:


> Mn6 and m12 are two different transmissions.My 05 is an m12. Same tranny that is in the z06. They are two different versions of the Tremec T-56. The m12 has shorter 1-3 gears an equal 1to1 4th and shorter 5th and 6th.
> 
> gear mn6 m12
> 1st 2.66 2.97
> ...


Actually, even the automatic in the Corvette is a conventional transmission, not a transaxle. It just has a different tailhousing, but it's still a plain old tranny.


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## HRJ (Mar 29, 2005)

Also, you might note that on the order build sheets.....MN6 is used to describe the trannys on the M6 GTO's even though it is actually a M12. GM says that MN6 is the "merchandising nomeclature"..........go figure.


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