[79 Phoenix]

Originally Posted by SD455DJ

I'm also in the throes of a "refurbishment" of an early (12C) GT-37 that is the opposite of yours when it comes to the option list. It's Canyon Copper with white guts and the red/white 'eyebrow' stripes. I have a thread on it that...https://forums.maxperformanceinc.com...d.php?t=790693

I'll be watching your progress with interest!

Dennis

Thanks Dennis. Beautiful GT-37! I will be following your thread as well... I'm sure I will learn a lot of much needed info.
Mine is as basic as they came. I don't think it has any options other than the GT package.. The one I had 40 years ago had the same 350 but it did have the 4 speed, tach in dash, wood grain cluster, PS, PB , vinyl seats. and trim rings When I drop the gas tank I hope to find the build sheet. I have high hopes it will be there as I am only the third owner. The car seems to have been maintained by the original owner just enough to keep it going till it came off the road in 92. It hasn't been messed with much as far as I can tell..

[Scarebird]

Originally Posted by SD455DJ

I'm also in the throes of a "refurbishment" of an early (12C) GT-37 ...
Dennis

Funny how the option sheet does not say boo about what transmission it has - I gather that if nothing is mentioned it defaults to manual 3 speed?

[unruhjonny]

correct, if the option page does not list it, then it had standard equipment.

[SD455DJ]

Originally Posted by Scarebird

Funny how the option sheet does not say boo about what transmission it has - I gather that if nothing is mentioned it defaults to manual 3 speed?

That's correct! I wish they had checked off the M-22 4-speed trans instead of the air conditioning, but it was ordered in Del Rio, TX, so pretty hot in the summers. I'm not sure if they understood they would get the M-13 3-speed if they didn't select a transmission option??? Anyway, back to the OP's thread.

Dennis

[Scarebird]

Originally Posted by SD455DJ

...I'm not sure if they understood they would get the M-13 3-speed if they didn't select a transmission option???...

The original owner may have been very wise depending on what 1st gear the 3 speed had and rear gears in back. Some of the 3 speeds had tall gearing, 3:1; coupled with say 3.08's and the torquey 455HO would make a very nice cruiser - an attribute here in the Southwest. At least it was not a column shift manual!

['ol Pinion head]

HD Muncie 3spd was only avail as one ratio transmission as the standard equip trans in GT-37's & GTO's. Nearly all non AC 71 GT-37's, I have info on from the Survey, have 3.55 gearing.
Original AC equip 455 HO stick 233's like Dennis's HO GT-37 & my HO Coupe received 3.31's. Non AC received 3.55's.

When a GT-37 was equipped with factory AC & a 350 2bbl stick or 400 4bbl, the ratio in the original 10 bolt would be 3.23.

[SD455DJ]

I believe the HD M-13 3-speed first gear ratio was 2.42, so better than the 2.20 first gear of an M-22 behind the 455HO engine.

Dennis

['ol Pinion head]

earlier comments were in connection to the HD Muncie 3spd in '71 Pontiac GT-37's & 400 GTO's, definitely a few different ratios in 3 spds of this era. The Coupe's original M22 & 3.31 XUK will see little time in the car.

[unruhjonny]

The 69-74 Muncie three speed only had two ratios:
The ‘car’ or “B” ratio: 2.42/1.58/1.00
The ‘truck’ or “A” ratio: 3.03/1.75/1.00
I believe that GM’s designation for this transmission was an SM-330 - but depending on the model year, platform or model, it could have one of several RPO’s.
I have read on occasion that some full sized cars could get the “A” ratio, but to date I have not found anything to confirm this.

My observations suggest that “B” gear set transmissions always had a front bearing retainer with an OD suited for a car bell housing, and a tail shaft for a floor shifter, while “A” gear set transmissions always had a front bearing retainer with an OD suited for a truck bell housing, and a tail shaft with no provisions for a floor shifter.

Saginaw three speeds seem to be another case all together;
I gave up on trying to understand GM’s coding for them, and what gear sets they came with;
in part because I didn’t have a baseline to compare anything against…

[79 Phoenix]

Originally Posted by 'ol Pinion head

HD Muncie 3spd was only avail as one ratio transmission as the standard equip trans in GT-37's & GTO's. Nearly all non AC 71 GT-37's, I have info on from the Survey, have 3.55 gearing.
Original AC equip 455 HO stick 233's like Dennis's HO GT-37 & my HO Coupe received 3.31's. Non AC received 3.55's.

When a GT-37 was equipped with factory AC & a 350 2bbl stick or 400 4bbl, the ratio in the original 10 bolt would be 3.23.

3.55 gears might explain why, with the GT-37 I had in the late 70's, I could get no better than 15 mpg while commuting 100's of highway miles each week. Mine was a 350 2bbl non-ac 4 speed. Low gas mileage was one of the reasons I sold it as gas was skyrocketing to upwards of $.80/ga!!!!

[79 Phoenix]

Originally Posted by unruhjonny

The 69-74 Muncie three speed only had two ratios:
The ‘car’ or “B” ratio: 2.42/1.58/1.00
The ‘truck’ or “A” ratio: 3.03/1.75/1.00
I believe that GM’s designation for this transmission was an SM-330 - but depending on the model year, platform or model, it could have one of several RPO’s.
I have read on occasion that some full sized cars could get the “A” ratio, but to date I have not found anything to confirm this.

My observations suggest that “B” gear set transmissions always had a front bearing retainer with an OD suited for a car bell housing, and a tail shaft for a floor shifter, while “A” gear set transmissions always had a front bearing retainer with an OD suited for a truck bell housing, and a tail shaft with no provisions for a floor shifter.

Saginaw three speeds seem to be another case all together;
I gave up on trying to understand GM’s coding for them, and what gear sets they came with;
in part because I didn’t have a baseline to compare anything against…

Good to know. Thanks!

[79 Phoenix]

Originally Posted by unruhjonny

correct, if the option page does not list it, then it had standard equipment.

When I get that far, I wonder if I could switch from current 3 speed to a 4 speed without affecting the originality and value of the car?

[unruhjonny]

if done properly, I doubt it would affect the value.

From the few first hand accounts I received from people who ran the Muncie three speed, they all suggested that it seemed to be gear perfectly, so I hope you're not looking for a dramatic increase in performance.

Everyone I have spoken to about this transmission cites it's bullet proof durability - and the only reason cited for swapping in a four speed, was for the "cool" factor.
(The guy who I got my '70 Muncie three speed, was quite clear in his assessment of making his car slower - his was a 350-2bbl Lemans of some sort.)

If you do go this route, you can swap over your chrome stick from the three speed shifter into an (OEM/correct) four speed shifter, and all you will be left to contend with is the reverse linkage.

Also, if you do go this route, there may be some people on this board who would be interested in getting that three speed transmission.

[79 Phoenix]

Originally Posted by unruhjonny

if done properly, I doubt it would affect the value.

From the few first hand accounts I received from people who ran the Muncie three speed, they all suggested that it seemed to be gear perfectly, so I hope you're not looking for a dramatic increase in performance.

Everyone I have spoken to about this transmission cites it's bullet proof durability - and the only reason cited for swapping in a four speed, was for the "cool" factor.
(The guy who I got my '70 Muncie three speed, was quite clear in his assessment of making his car slower - his was a 350-2bbl Lemans of some sort.)

If you do go this route, you can swap over your chrome stick from the three speed shifter into an (OEM/correct) four speed shifter, and all you will be left to contend with is the reverse linkage.

Also, if you do go this route, there may be some people on this board who would be interested in getting that three speed transmission.

Hmmm... Thanks. That's good food for thought. I appreciate your input!

[SD455DJ]

Originally Posted by 79 Phoenix

When I get that far, I wonder if I could switch from current 3 speed to a 4 speed without affecting the originality and value of the car?

I changed to a B-W ST-10 4-speed with the 2.64 1st gear since my M-13 was worn out. It's in my thread somewhere...but I don't believe changing over to a 4-speed, especially an M-20 Muncie, would reduce the value at all. Just keep your original M-13. I just had to get the correct levers/rods to work with the trans which I got from Crash Enterprises. I reused the original shifter handle & 3-spd pattern ball, so you would never know there was a change. The original back-drive all worked too.

Dennis

[79 Phoenix]

Originally Posted by SD455DJ

I changed to a B-W ST-10 4-speed with the 2.64 1st gear since my M-13 was worn out. It's in my thread somewhere...but I don't believe changing over to a 4-speed, especially an M-20 Muncie, would reduce the value at all. Just keep your original M-13. I just had to get the correct levers/rods to work with the trans which I got from Crash Enterprises. I reused the original shifter handle & 3-spd pattern ball, so you would never know there was a change. The original back-drive all worked too.

Dennis

Good info. Thanks!

[Baron Von Zeppelin]

Originally Posted by 79 Phoenix

When I drop the gas tank I hope to find the build sheet...

Hope you have good luck on that.
Which plant was it built at ?
If it was Atlanta , they usually had one taped on the inside of a door panel

You might have a handful of minor options.
Carpet
Radio ? do you have an in-glass antenna in the windshield ?
SoftRay windshield ?
Recess wipers ?
super lucky would be a saf-t-track rear axle

These other guys will know for sure but seems like they all came with Rally2 wheels

[SD455DJ]

Originally Posted by Baron Von Zeppelin

Hope you have good luck on that.
Which plant was it built at ?
If it was Atlanta , they usually had one taped on the inside of a door panel

You might have a handful of minor options.
Carpet
Radio ? do you have an in-glass antenna in the windshield ?
SoftRay windshield ?
Recess wipers ?
super lucky would be a saf-t-track rear axle

These other guys will know for sure but seems like they all came with Rally2 wheels

Yep, Rally II wheels without the trim rings came with the GT-37 package.

Dennis

[79 Phoenix]

Originally Posted by Baron Von Zeppelin

Hope you have good luck on that.
Which plant was it built at ?
If it was Atlanta , they usually had one taped on the inside of a door panel

You might have a handful of minor options.
Carpet
Radio ? do you have an in-glass antenna in the windshield ?
SoftRay windshield ?
Recess wipers ?
super lucky would be a saf-t-track rear axle

These other guys will know for sure but seems like they all came with Rally2 wheels

Yes it has carpet, AM radio--antenna must be in windshield which is tinted. Wipers are recessed... That would be neat if it's posi.

[79 Phoenix]

Originally Posted by SD455DJ

Yep, Rally II wheels without the trim rings came with the GT-37 package.

Dennis

Yes I like them without the trim rings... The one I had years ago had them but now I prefer w/o.