# Can someone help me ID this Transmission



## tonyskala (Feb 7, 2015)

I am having a really hard time figuring out what this transmission is. 

It come off a 64 Bonneville. 

I think it is a Hydra-Matic 315 transmission. But Someone told me it is a GM Roto Hydramatic transmission.

I know I know, The bell housing is smashed. The guy I got it from could not separate it. So he smashed it with a hammer. He still did not separate it. I got it like this. 

Anyway if anyone knows what it is I would appreciate it. He told me it was a heavy duty transmission and people liked them for ls2 conversions because they handled torque real well. But 3 of the 4 things he told me were a lie so I duno


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## tonyskala (Feb 7, 2015)

Oh the tag on it is not legible. and there are no cast numbers on it that I can see.


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## PontiacJim (Dec 29, 2012)

tonyskala said:


> I am having a really hard time figuring out what this transmission is.
> 
> It come off a 64 Bonneville.
> 
> ...


Yep, looks like the older 1964 and under Hydramatic. Has the 2-piece torque converter/ring gear. They were the common trans in GM cars. My first car, '56 Pontiac, had the Dual-Range Hydramatic and these were 4-speeds with a 1:1 4th gear. Made the cars very fast even though smaller cubic inch engines (316CI for the '56 Pontiac). Very heavy as they were cast iron. Pulled mine out to install a factory 3-speed/column shift from a donor car. It was fun but the trans was weak and started to give problems and then the clutch linkage finally gave up one day. So back in went the Hydramatic. Then it developed a leak/crack in the torque converter shell and a trans shop welded it up for me and I was good to go.

The Hydramatic was a popular trans with drag racers and B&M was one of the name brands who built them them for the drags. I had one, but never got to use it.

Check out this website as you can click on the transmission types and then take a look at the exploded parts as well. The Hydramatic, Jetaway 315, and the Roto-Hydramatic (known as the "Slim Jim"). The "Slim Jim" from all accounts I have heard was junk and did not hold up well to hi-horsepower or abuse. The pan is kinda odd looking and is different from yours, so it does not appear to be the Roto-Hydramatic. Click on this link: Early GM Transmissions


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## tonyskala (Feb 7, 2015)

That was extremely helpful. A million thanks.


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## HAMMERPETE (6 mo ago)

tonyskala said:


> Oh the tag on it is not legible. and there are no cast numbers on it that I can see.


THE TRANS IS A JETAWAY MODEL 315 USED IN AMC,CADS, HUDSON,OLDS & PONTIACS THE ROTO 5 & 10 ARE ALUM. TRANS WITH NO CONVERTERS


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## O52 (Jan 27, 2019)

Rotos were used in the short wheelbase B bodies like the Catalina, 2+2, Grand Prix. Four speed Hydromatics were in the long wheelbase Bonneville and Star Chiefs. Unfortunately the floor over the trans was also smaller in the Catalinas prohibiting installation of the Hydros and T400s without some modification. By 65 all the B bodies used the T400

The Roto in the 64 Catalina I once owned never gave me any trouble at all. I still kick myself for selling the car.


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## PontiacJim (Dec 29, 2012)

HAMMERPETE said:


> THE TRANS IS A JETAWAY MODEL 315 USED IN AMC,CADS, HUDSON,OLDS & PONTIACS THE ROTO 5 & 10 ARE ALUM. TRANS WITH NO CONVERTERS


The converter bolts to the flywheel section - it is 2 pieces. You can see the bolts along the outer edge where the bell is busted? That was what I based it on and my experience with my '56 dual range hydramatic. Not expert, but that does not look like an 8" fluid coupling integral with the transmission, but again, no expert on these older tansmissions and it simply could be the photos supplied.

I did find this:

*Roto Hydramatic* (sometimes spelled Roto Hydra-Matic or Roto-Hydramatic) was an automatic transmission built by General Motors and used on some Oldsmobile, Pontiac and Holden models from 1961–1965. It was based on the earlier, four-speed Hydramatic, but was more compact, providing only three forward speeds plus a small 8" fluid coupling with a stator inside of the fluid coupling (a type of torque converter, only integral with the transmission rather than being an independent unit).


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## tonyskala (Feb 7, 2015)

So I actually sold this transmission a while back to someone in New Zealand. He was so happy I had it. I guess he was having a tough time finding parts


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