[unruhjonny]

Another thread that has recently been active has caused me to go down a rabbit trail. To be quite frank, with the ongoing lockdowns which started as "2 week to break the curve", and no end in sight, I don't think chasing a rabbit trail is such a bad thing - it provides refuge for the mind to be occupied outside of politics.

What I would like to do, is try to make a list of three speed manual transmissions with a means of identifying them, and right now I seem to be stumped on two things:

1) the GM code for the 1966-1987 Saginaw three speed;
I believe that GM called it a SM326, but I found reference to it also being called an SM342;
Maybe GM used both, and one code indicated a departure in one way or another from the other code.
I am sitting here questioning if the '342' is a non-GM designation, as companies such as Hurst (which is an easy example in this case) has given different transmissions a three digit number code - as seen here:
https://documents.holley.com/techlibrary_manual.pdf
It appears as though the Hurst designation is '343', while Borg-Warner has designated it as a '301'.

2) The various Borg-Warner (in house) manufactured three speeds are also confusing me.
I am seeing at least a half dozen different ones, but various sites seem to suggest it was the T-16, or the T-85, or the T-86, or maybe the T-89 from which the T-10 four speed was derived;
I believe based on my research, that the T-85 was the transmission that the T-10 was derived from, and that the T-16 & T-86 are wholly different from the T-85, while the T-89 was a derivative of the T-85.
I do not know if one or more of these codes is for the same transmission.
As another point of example, this is a nice article that I found on the T-85/T-89:
https://www.hemmings.com/stories/art...-transmissions

Ideally I'd like make a list that gives the GM code name (EG: SM318 vs SM330 vs SM465) or manufacturers real name instead of simply calling it a "Saginaw" or "Muncie" or a "Borg-Warner".

I'd also like to list pertinent info such as side cover bolt number, is the first gear is synchronized, if it was classed as a light duty versus heavy duty gear box, or if there is something distinct which might be why it is considered a different transmission (EG: T-85 vs T-89).

I have a working document, but being that I lack the knowledge which only comes over time that some of you seem so generous in sharing, I am guessing that someone, or some of you, can help me compile this information.

My current list starts with the Muncie sourced SM318/SM319 which I believe started being manufactured for passenger vehicles in 1940 and was made through to 1969.
I don't see the need to list EVERY three speed known to man, but would rather touch on all three speeds that could be found in 1960's and newer GM vehicles, with some other period transmissions from the same time to spice it up.

[unruhjonny]

I figured that today was a good day to bump this thread – seeing as is was one year ago that I created this thread(!)

Can anyone help me make sense of the different three speeds that GM used, along with their transmission designations?
(EG: SM318 vs SM330 vs SM465)

I essentially want to create a “cheat sheet” of sorts for identifying the different GM three speeds.

The reason that I want to do this is that discussion of three speeds is virtually non-existent these days, and this information is being lost to time.

Some fun facts that I have learned over the past while are:

When my car was new (1970) three speeds were so common, that manufacturers often didn’t put shift patters on three speed shifter handles;

Have you noticed those red arrowhead crests on older GTO shifter handles?



Those are all three speed knobs!

Only once you get into the 1970's was there a shift (pun intended) to put the shift pattern on three speed knobs.


And those “HURST” shifter T-handles without a shift pattern(?)



Those were actually made that way, to be used as three speed shifter handles - they have since been accepted as universal, but that wasn't the original intent (from what I have learned).

Anyway, that's it...

Just giving this thread a bump incase someone sees it, and can contribute in any way.

Thanks for looking

[chuckies76ta]

A bit of info. https://www.pontiacsafari.com/L1Gara...ions/index.htm

[unruhjonny]

oh!!

Nice!

Thank you VERY much!

I recognize your user ID - aren't you from Edmonton?

[rwfisher]

The Hurst name only grip was available from hurst thru the aftermarket for many different thread patterns in the 70’s. I ran 1 on 3 different vehicles, 1954 F-100, 1979 Mercury Zephyr Z-7, and a 1978 Firebird Formula. Pretty easy to get off the shelf, I still have the one from the Formula…. Later years they also could be had with a line lock switch, still no shift pattern. My 69’ T/A came with the Dearborn 3 speed so I also have that same Pontiac arrowhead walnut knob you show for that….. I often wondered if the drag strip times with a 3-speed and good gearing looked better than a 4 speed?? Probably not or everybody would have ran them!!

Originally Posted by unruhjonny

I figured that today was a good day to bump this thread – seeing as is was one year ago that I created this thread(!)

Can anyone help me make sense of the different three speeds that GM used, along with their transmission designations?
(EG: SM318 vs SM330 vs SM465)

I essentially want to create a “cheat sheet” of sorts for identifying the different GM three speeds.

The reason that I want to do this is that discussion of three speeds is virtually non-existent these days, and this information is being lost to time.

Some fun facts that I have learned over the past while are:

When my car was new (1970) three speeds were so common, that manufacturers often didn’t put shift patters on three speed shifter handles;

Have you noticed those red arrowhead crests on older GTO shifter handles?



Those are all three speed knobs!

Only once you get into the 1970's was there a shift (pun intended) to put the shift pattern on three speed knobs.


And those “HURST” shifter T-handles without a shift pattern(?)



Those were actually made that way, to be used as three speed shifter handles - they have since been accepted as universal, but that wasn't the original intent (from what I have learned).

Anyway, that's it...

Just giving this thread a bump incase someone sees it, and can contribute in any way.

Thanks for looking

[unruhjonny]

Originally Posted by rwfisher

... I often wondered if the drag strip times with a 3-speed and good gearing looked better than a 4 speed?? ...

I have read that they WERE generally faster, BUT, they lacked the "cool" factor of the four speed.

[unruhjonny]

I am looking into this again;
It really seems as though this three speed information is being lost to time.

I came across what might be an article which may help me out, but it looks like I cannot sign up to be a paid member of this ecklers site.
The article is entitled:
Corvette Saginaw 3-Speed Transmissions

(this picture is at the top of the article)

Unless I am mistaken this picture is only adding to the confusion because it looks like a long tail housing Muncie 318 is being called a Saginaw here...

I think I have some of this straight, but really would like to clear up the Saginaw transmission RPOs against what they were;
I found some information which suggested that GM used a different RPO for different gear sets on Saginaws, but I think this may be mistaken - as the Muncie 3spd appears to have an SM330 designation, regaurdless of application or gear set.

Please correct me if you know that anything I have written is wrong.

[Skip Fix]

I know one of my street racing buddies from the 70s had a Pontiac motor and a stick in a 65 Chevelle, then a 69 GTO and finally a 65 GTO. He felt the 3 speed was faster and he had some fast cars.

[1968GTO421]

I don't know much about GM 3 speeds, but Chrysler had two three speeds during the '70's. I/ve had both in cars/trucks. One was the A250 which was no-synchro on 1st gear and the A-230 which was all synchro on forward gears. A230 worked great on a Duster I had with a modified 318.

FWIW I found this list on Wikipedia:

Saginaw M26/27 transmission — 3 and 4-speed longitudinal light duty (less than 300 hp) wide ratio manual transmission made by GM at their Saginaw, Michigan factory

Muncie M62/M64 — 3-speed longitudinal transmission made by GM

Borg-Warner R-10 overdrive - 3-speed manual transmission with electric overdrive used 1937-1964

Borg-Warner R-11 overdrive - 3-speed manual transmission with electric overdrive Ford used them up until 1975 in trucks.

The entire list of all trannys is here: (I culled out the 3speeds) https://en.wikipedia.org/wiki/List_of_GM_transmissions
FWIW