About the three speed transmission

[Paul P.]

Hello:

I'm in the process of researching an article for my vintage Corvette club, the subject being transmissions.

I have some questions on the three speed manual, first seen in 1955, last seen in 1969.

I've attached a couple of photos I took of a three speed manual transmission demo that I found at an overpriced automobile memorabilia store. I recall that there is an industry name for these, not sure what it is. It is labeled as a "'57 Chevy 3 Speed". My first question: is this the same as found in the Corvette?

Another thread has the later three speeds featuring synchro first gear, true?

One 1958 three speed owner said it really wasn't a good sports car transmission, besides not offering a fourth gear. He claimed it originated as a truck transmission and the linkage did not offer good sports car shifting characteristics. Any opinions? Have not driven one myself.

I put a quickie spread sheet together (available at http://corvettestory.com/temp/Three_...ual_Notes.xlsx) covering the quantities from 1957 to 1969. It is derived from the Corvette Black Book data. Basically I totaled up all the other transmission quantities and subtracted them from the production quantities to get three speed manual numbers. It shows 252 for 1969 and 919 for 1963 for example. I did this as I've never seen a three speed manual C2 or C3 and was curious.

Any comments on the spreadsheet or the process are welcome.

~paul

[Keith W.]

Re: Aout the three speed transmission

Paul
I have a 66 with 3 speed - non ordered radio - base engine

[Jim L.]

Re: Aout the three speed transmission

Paul,

The pictured transmission is, indeed, for a '57 passenger car. It is a wide radio box with 2.94 low gear. Corvette 3 speeds would have had a 2.2 low gear and a boss on the tail shaft for shifter mounting. 1st gear is not synchronized.

Jim

[Todd H.]

Re: Aout the three speed transmission

Paul,

The original owner of my '57 told me that the 3 speed in our car was so bad that he simply threw it away when he replaced it with a 4 speed immediately after buying the car in 1957. He said there was no way that anyone would buy it, and why hang on to a worthless transmission? He wanted 4th gear, but the lack of the first gear synchro was just as bad as no 4th to him.

Of course, he wasn't looking for a grocery getter. He wanted to go racing.

[Paul P.]

Re: Aout the three speed transmission

Jim:

Cool.

For the purposes of my article, it looks like I would be accurate saying that the "transmission shown in the photo is from a 1957 passenger Chevrolet which is similar to the three speed transmission installed on the Corvette".

>> Corvette 3 speeds would have had a 2.2 low gear and a boss on the tail shaft for shifter mounting.
Interesting. I assume the lack of a boss on the tail shaft is due to the standard passenger car having a steering column mounted shifter?

~paul

[Paul P.]

Re: Aout the three speed transmission

Todd:

>> he simply threw it away
>> why hang on to a worthless transmission?

I love hearing those stories. Times and circumstances sure have changed!

~paul

[Gary C.]

Re: Aout the three speed transmission

Paul,

FYI - early Restorer Magazines there were several good articles written on 3 speed transmissions by Paul Hendrickson.

Gary
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[Jim L.]

Re: Aout the three speed transmission

Jim:

Cool.

For the purposes of my article, it looks like I would be accurate saying that the "transmission shown in the photo is from a 1957 passenger Chevrolet which is similar to the three speed transmission installed on the Corvette".

That would be accurate.

>> Corvette 3 speeds would have had a 2.2 low gear and a boss on the tail shaft for shifter mounting.
Interesting. I assume the lack of a boss on the tail shaft is due to the standard passenger car having a steering column mounted shifter?

~paul

True. There was no need for the shifter mount bosses in passenger applications.

Oh, and another difference in the tail shaft housings was the presence of a transmission mount boss in Corvette applications. Not needed in passenger applications since the transmission hung out in space, being supported by the four bell housing attachment bolts.

And as long as I'm doing a brain dump of what little I know about 3 speed transmissions: Beginning in '57, the side cover incorporated a mechanical interlock which prevented being able to select two gears simultaneously (like 3rd and reverse, for example). In your picture, you can see this interlock. It was not present on '55 and '56 side covers.

Jim

[Gary C.]

Re: Aout the three speed transmission

Jim,

Also, in March '57 the shift gift was enlarged on 3 speeds. IIRC the shift gate was the same as a 4 speed.

Gary
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[Gene M.]

Re: Aout the three speed transmission

Last year of non synchro was 65. It had mounting for the shifter. The synchro version had to mount shifter to frame mount only. The tranny changed entirely in 66 to full synchro. Still cast iron case into 67. I don’t know after that.

[Jim L.]

Re: Aout the three speed transmission

Jim,

Also, in March '57 the shift gift was enlarged on 3 speeds. IIRC the shift gate was the same as a 4 speed.

Gary
....

Not sure I'm following you, Gary. Are you saying that shift lever travel for 3 speeds increased?

[Gary C.]

Re: Aout the three speed transmission

Jim,

Top of the shifter housing where the shifter handle goes through.


Gary
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[Gary C.]

Re: Aout the three speed transmission

Screenshots of the different shifters from the 1957 AIM. After the 4 speed was introduced in April '57, the 3 speeds used the same bracket with the large shifter opening.

[Jim L.]

Re: Aout the three speed transmission

Thanks, Gary! That clears it up perfectly.

Learn somethin' new every day.....

[Gary C.]

Re: Aout the three speed transmission

Jim,

Somewhere in the C2's the tailshaft design was changed, but that's above my wheelhouse.

There's some other tailshaft changes in 56-7, but I'd have to dig out my archived cliffnotes.

Gary
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