I've seen this several places in the GM Parts wiki. For example, in the 1972 Cutlass/442/Vista Cruiser Assembly Manual on page 204 is drawing "Chart- Engine Conversion" - on that page is a chart titled "to convert S. M. engines to C60, the following is required"

I have a list of "Chassis Abbreviations" from Olds Parts and Accessories Catalog Jan 1972, but it does not show "S. M."

What does "S. M." mean?

 

It means manual transmission

 

What 66SportCoupe said. The term GM used for their manual transmissions over a certain period was "Synchro-Mesh" and that's what S.M. referred to.

Randy C.

 

To add what I believe is a bit history...........
Manual transmissions have been around forever. You had to come to a stop or come almost a complete stop to engage first gear.....or perhaps some fancy "double clutching" and gear grinding. Somewhere in the 60's I believe, engineers figured out a way to make 3 speed (maybe 4 speed) manual transmissions engage first gear while in motion. No fancy footwork was needed, just shift into first at any appropriate speed. This became a "sales" feature in new car literature. After that, all manual transmissions were referred to as "SM". Oldsmobile refers to them as SMT (Synchro Mesh Transmission).

 

That's what the synchronization rings, aka- blocking rings, do. They mate to a cone on the gear and provide a braking effect to match the speeds better.

 

Thanks to all who responded. I'm old enough to remember those non-synchronized manual transmissions.

 

Me too. And modern manual trans are synchronized in reverse, which I still marvel at each time I shift while moving.

 

Me three, remember doing autocross on a tight course. Grinding as I down shifted to first every time. Tedd

 

To expand on this, the reason why the 1971-72 350 engines specifically called out differences when converting manual trans engines to A/C (C60) had to do with how the Transmission Controlled Spark system was plumbed. The non-A/C 350 motors did not get the thermal vacuum switch in the vac advance plumbing those years, just the solenoid valve. A/C cars tended to run hotter, so it was necessary to change out the TCS solenoid valve for the integrated solenoid valve and thermal vacuum switch that also switched to full manifold vacuum for advance if the car started to overheat. If you carefully review those conversion lists of parts removed and installed, you'll see this.

 

Oh. I thought it stood for Sado-Masochism.

 

I knew SOMEBODY was going to bring that up.

 

Ha, I was waiting for that! You know what they say about great minds.

 

🤣🤣😂

 

so on the Cutlass "S" - what does the "S" on the Fender and other places stand for ?

 

Do you really want to know?

 

Very interesting, meant sincerely.

 

There's always that one guy, lol.

I would think Sport.

 

I too am old. I remember how trying to down shift a three on the tree was not happening. I went from that to a Peterbilt and never using the clutch to change gears.

 

It is also referred to as SMT.



Definitely agree. In '70 you could not get the W-31 package or even a four speed transmission (SMT) in the Cutlass. This held true up into the '90s on the Calais and Quad 442 models. The base Calais offered 5 speed SMT, but not with the Quad Four. Only the Calais S offered the W-40/41 with a manual transmission.