1963 Hydra-Matic interchange

[Guest imported_Pertti K]

Are 1963 Oldsmobile and Cadillac Hydra-Matic transmissions interchangeable or two totally different transmissions. There's an opportunity for me to buy a rebuilt Cadillac transmission, but I need to be sure if it fits my '63 Starfire.

Thanks again!

Pertti

[rocketraider]

Not as a direct bolt-in. Cadillac was still using the 4-speed Controlled Coupling HydraMatic 1961-64.

Here's the breakdown on HydraMatic usage:

1961-64 ALL Oldsmobiles, and Pontiac Catalina and Grand Prix used the Roto Hydramatic 375 "Slim Jim"

1961-64 Pontiac Star Chief, Bonneville and ALL Cadillacs used the Controlled Coupling (Cad) or Super (Pontiac) HydraMatic.

Here's a thread from RealOldsPower that addresses adapting a HydraMatic to a SlimJim car. It's actually discussing use of an old B&M HydroStick racing HydraMatic, but I think you'd have to do the same things to adapt the Caddy transmission. BlownOlds is on here sometimes too, you might try contacting him.

http://www.realoldspower.com/phpBB2/viewtopic.php?t=17913&highlight=

394 transmission swap

[Guest imported_Pertti K]

OK, thanks! I want to keep my Starfire as original as possible, so swap is no option. I'll just have to rebuild the slim jim if necessary.

[RShepherd]

Not all 1964 Cadillacs used the four-speed Controlled-Coupling Hydramatics. The Fleetwood 75's and the 62 series did, but the de Villes and Fleetwood 60's used the new-for-'64 Turbo-Hydramatic. It's easy to tell which transmission is in a '64 Cadillac: Park,Neutral,Two Drives, Low, Reverse is Hydramatic;Park Reverse Neutral Drive (only one in '64)and Low is Turbo-Hydramatic.

[rocketraider]

Good point and correction! I knew the commercial chassis and 62 had it, and was thinking the rest did too. Forgot the THM was a new-for 64 introduction for Cadillac and Buick. <img src="http://forums.aaca.org/images/graemlins/blush.gif" alt="" /> Had also forgot about the PRNDL selector on the earliest THMs, and I've seen a bunch of Rivieras with that.

[Pontiac59]

The Slim-Jim is notorious for failures, while the 4-speed dual coupling is a pretty stout unit. Unless your car is a for-points-show-only vehicle, I'd make the switch. I'd rather change something that 95% of people will never see and of those few who do most won't know the difference anyways, than get stuck somewhere or have to rebuild the same trans 15 times.

Dual Couplings used 1960 and prior, with which I am familiar, use a different short bellhousing to bolt up to their respective Pontiac, Olds and Cad engines. I'm not familiar with Olds engine bolt patterns enough to know if a 1959-1960 adapter would bolt to a newer block to use the D-C Hydro.

The 4-speed trans will also improve gas milage -

[dlh61olds]

Here is a place you can get some really good info.

http://www.transmissionadapters.com/early_olds.htm

Let us know what you decide to do .

I have a car with the ( slim jim ) I thot about converting to a stick.

I found out I had to move the power brake assembly to under the

drivers feet to make room for the clutch lever assembly.

Look at the whole picture before deciding. You might have to build

new transmission mounts ETC. to accomodate a different unit. And

then, there is the actual shift mechanism to consider.

Thanx, Dave

[Pontiac59]

I know that in the Pontiacs the one thing that stops it from being a direct bolt-in conversion is the floorpan. The Slim-Jim is smaller, and the trans tunnel is also smaller. It seems likely that would be the case in the Olds as well, meaning that a donor vehicle trans hump would have to be cut out and welded or bolted in.

That sounds like a lot of work, but on the bright side the welds will also not be that visible, they don't have to be finished to the 10th degree. Plus, that's usually the last part of the floor to rust out, so it should be an easy part to come up with.

[Oldsfan]

Well, I'm gonna turn thing into a Pontiac thread...

Not all Pontiacs used the Slim Jims. Bonnevilles (& Star Chiefs?) used the old dual range. They had to fit under the floor. You mean they had two different floor pans in those Pontiacs?

And what did Cadillac do with their transmissions? Did they use a separate bellhousing like Pontiac did? It's too bad that you can directly bolt a THM to the back of a Pontiac, or a Cadillac, but not an Olds...

Paul

[rocketraider]

Entirely possible since Star Chief/Bonneville were physically longer cars than Catalina/GP.

We must remember that Olds often did things "their way" back then.

I just realised that while a THM cannot be bolted to a Rocket block, it is entirely possible to mate a Slim Jim or 4-speed HydraMatic to a 65-later Olds engine by using a Pontiac bellhousing. <img src="http://forums.aaca.org/images/graemlins/shocked.gif" alt="" /> <img src="http://forums.aaca.org/images/graemlins/crazy.gif" alt="" />

[Oldsfan]

Never thought about the Bonnevilles being longer. But this leaves me with many other questions that I am not going to raise here because it is, after all, an Oldsmobile forum. <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

Paul

[Pontiac59]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Well, I'm gonna turn thing into a Pontiac thread...

Not all Pontiacs used the Slim Jims. Bonnevilles (& Star Chiefs?) used the old dual range. They had to fit under the floor. You mean they had two different floor pans in those Pontiacs?

And what did Cadillac do with their transmissions? Did they use a separate bellhousing like Pontiac did? It's too bad that you can directly bolt a THM to the back of a Pontiac, or a Cadillac, but not an Olds...

Paul </div></div>

Yes, two different floorpans. Quarters and deck also different, the added length in those years was in the rear, not the front.

You can bolt a THM to a Pontiac, but until late 64 most do not have holes in the block to mount a starter, they bolted front to back to the bellhousing. Someone is (was?) making an adapter to allow you to run the later trans in these cars.