LT-1 equipped with M-20

[lazybee99]

Anyone have any idea of the numbers of 70 LT-1s equipped with the M-20 instead of the M-21

 

[Gus]

M-20

According to the corvette Black book, NO LT-1s were built with a M-20 transmission...
by the way WHAT is a M-20....for some reason I am thinking that the M-20 was a automatic?

Is this correct?

M-22's were on some LT-1s, mainly the ZR-1 packages, but I have "heard" they could be ordered on the big blocks and even some regular LT-1's

I have seen some Holley carbs, which were designated to LT-1's with automatics,
but I have never seen one on a legit LT-1 that had an automatic.

hope this helps a little.
Larry (gus)
webmaster for
www.lt-1registry.com

 

[lazybee99]

black book wrong

The M-20 was the wide ratio 4 speed, M-20 was the close ratio. My LT-1 is equipped with the M-20. This is verified by the original transmission that is in the car (VIN stamped, and more important, by the tank sticker listing a M-20)

I am just trying to determine how rare this combo was (LT-1 and M-20)

 

[Gus]

M-20

Hi again,

Duh, I KNEW that, had a brain lapse.

Actually the Black book is correct,
you (meaning I) just have to look deeper into it to find the info that you are looking for.

THe M-20 is a wide ratio manual transmission,
it came standard on the base corvette with the 350/300 horse engine.

The black book does not say how many were made with the LT-1's,
but I would assume that it would be fairly rare since I think that the M-21 was standard for the LT-1, but I need to check on that as well. If it was standard on the LT-1's then the vast majority opted for the M-21 when ordering the LT-1's.......interesting.

You would be the FIRST M-20 I have heard about,
please take the time to come register your LT-1 at the registry.

thanks for the heads up
Larry (gus)

 

[72LT1Steve]

Lazybee99;

The 70-72 LT-1 came standard with the M-20 wide ratio 4-speed, with the M-21 4-speed being a no cost option if the dealer or ordering customer wanted it over the the M-20 wide ratio. Then it would be used at no charge. However the selection did effect the rear-end ratio selection in '70 (as well as other years).

LT-1 w/M-20: Std ratio: 3.55 Econ. ratio: 3.36 Perf. ratio: 3.70

LT-1 w/M-21: Std ratio: 3.70 Econ. ratio: 3.55 Perf. ratio: 4.11

Unfortunately I have never seen any production figures for what was produced. It does seem though more M-21's were chosen over M-20's

(Mine: M-21 w/ 3.70 rear)

Hope this helps in some way.

Steve
'72 LT-1 Convertible

 

[Fitz]

LT-1 Production Numbers

lazybee:

Don't wish to argue, but...I gotta side with gus.
Rowley's Corvette maintains an archive for production numbers for model years 1953 through 1972 at http://rowleycorvette.com/vettestats.html
they don't match up all of the possible options configurations but do show total production for the LT-1 option.
records show 1970 code CTV indicated 350..370 hp Perf. Pkg, LT1 Engine, with M22 4-Speed
1970 code CTV production -LT1 350ci, 370hp Engine 1,287
1971 the code changed to CGY . 350..330 HP Perf. Pkge, LT1 Engine, M22 4-Spd. (Note reduction in HP)
1971 production LT1 350ci, 330hp Engine 1,949

1972 saw another code change: CKZ . 350 .255 HP Perf. Pkge, LT1 Eng, M22 4-Spd (with another drop in HP)
1972 production LT1 350ci, 255hp Engine 1,741
Can't tell if any LT1 cars were delivered with anything other than M22 4 speed. This indicates no. Isn't history wonderful?
Fitz

 

[lazybee99]

m-20

Well at the very least it seems as though there is conflicting info. When I first read my tank sticker I thought I was reading it wrong where it stated "03M20AA" So I again went under the car and verified the stamped "A" on the tranny.

I am sure there are others out there but guess there is no way to say how many.

 

[lazybee99]

addition

On a side not, my car also came with the 3:55 rear end.

 

[jbua]

M20 Trans

The M20's were standard and the M21's a no cost option.

the M22 Rock Crusher was available and seems to be only on the ZR-1 in 1970 based on several publications.

 

[rainman]

LT-1 trans

I have a 71 LT-1 that I have owned for about a year. I do not have the tank sticker, protecto plate, etc. The car is fairly orginal with all numbers that I can verify correct. I'm having a problem determining if I have the M20 or 21 transmission. The car's vin is on the transmission as well as the correct Muncie date code, but the date code does not carry the A, B, or C for the M20, 21, or 22. Also the car has a 3.70 rear. I am interested if anyone has an explaination for the lack of the lettered sufix.

 

[gdh]

Thanks Fitz, I see that there were only 20 of the ZR-1's produced. I have a vert. just wondering how many of those 20 were convertibles.

 

[72LT1Steve]

Re: LT-1 trans

I have a 71 LT-1 that I have owned for about a year. I do not have the tank sticker, protecto plate, etc. The car is fairly orginal with all numbers that I can verify correct.

I'm having a problem determining if I have the M20 or 21 transmission.

The car's vin is on the transmission as well as the correct Muncie date code, but the date code does not carry the A, B, or C for the M20, 21, or 22. Also the car has a 3.70 rear. I am interested if anyone has an explaination for the lack of the lettered sufix.

Rainman: I checked through my various resorce materials and couldn't come up with a answer to the M20 or M21 question. I did locate the following axle ratios from standard through performance, but I don't know if it helps at all:

Standard Economy Performance

M-20: 3.70 3.55 4.11

M-21 3.55 3.36 3.70


I have an M-21 w/3.70 rear in my car. At a 60 to 70 MPH cruising speed, my tach is around 3200 RPM.
Sorry I didn't have more (

Steve

 

[Robert N]

I believe that the 1970 LT-1 came with the M21 as standard, the ZR-1 (25 produced in 1970) came with the M22 standard. The close ratio options were matched to the engine for performance as the M20 was designed for economy.