70 GSX 4 speed question

I have a few questions: What 4 speed do a 4 speed GSX come with? A M21? What are the gear ratio's in the correct transmission? Thanks for any info. Paul

 

Hey Paul!!

Unless I'm mistaken, the '70 GSX should have been equipped with the Muncie M21 close ratio gearbox with a 2.20 first gear. Pretty sure all Gran Sports with a 4 speed were so equipped.

Rob

 

Hey Paul - I hope you are well.

Yes - Buick used M21 Muncie transmissions.

Ratios:
M21 2.20 1.64 1.28 1.00

http://www.5speeds.com/muncie/home/new-transmissions/gear-ratios/

 

Thanks Marco. We are doing well and hope you are also. My car was a 4 speed car originally but the owner back in the 70s put in a Turbo 400. When I bought the car, I had a friend with a Super T10 and we put that in the car and it has been in the car 25 years. It started making some grinding noise so I want to restore the car to a transmission that would have been in it when new. A Muncie M21 I think would work well. I wonder if the shifter I use with that Super T10 will work with a M21. Have a great 4th! Paul

 

Thanks Rob!

 

It is not just any M21. It is a M21 with the tail shaft number plumbed for the factory TCS. You will also need the correct external speedo reduction accessory and the cable.

http://www.v8buick.com/showthread.php?280019-TCS-4-Speed-Switch&highlight=tsc+switch+4+speed

 

Thanks for the info. Paul

 

No problem Paul! Perhaps we'll see you again soon at the Tuesday Evening shindig in MC.

 

See you there!

 

What were Buick & Oldsmobile thinking? The M-22 was long since available to Chevy & Pontiac yet neither Buick nor Olds offered the M-22 transmission when it was really needed in 1970.

Oldsmobile offered the M-22 one year only in 1971. By then the compression drop already took a bite out of the torque that the standard & W-30 versions of the 455. Better late than never I guess.

Then in 1972 & 1973 ONLY the M-20 was available in an Olds even with the optional 3.73 gears (my 72 W-30 was so equipped with M-20 & 3.73 gears).

Question....Did Buick offer the M-22 transmission in any year before it was made obsolete by GM in 1974?

 

No

 

I found a guy who will build me a M21 with the proper casting numbers. Does anyone know the casting numbers for a 70 car for the case and tailshaft. Thanks for any info. Paul

 

see post #6 above re the TCS switch and the tail shaft. Dennis M will likely have those parts and maybe the speedo adaptor.