Odd twist on same old Hydramatic question

I have a twist on the same old hydramatic trans question and I hope some of the experts here could tell me if I’m trying the impossible. I’ve searched this forum (and elsewhere) and found many excellent threads, but not the exact info I need.

I am looking to swap an engine into a 55 Nash Ambassador and I would like to continue using the stock transmission in the car, which is a 55 GM dual-range / 4 speed / iron case Hydramatic. Replacing the whole drive train is a much bigger problem since it uses a torque tube and the car is a unibody. Besides, an SBC / T350 / Ford 9” would just not have the same character as the funky Nash setup. So I am trying to build a list of GM motor & bellhousing combinations that should bolt up to my Hydramatic. I know the parts are going to be hard to find, but I’d like to know what would work.

Some details: My hydramatic is flat-pan, not slant like 54 and later Olds. This is a picture with bellhousing off:
http://wheeltramps.com/gallery/Hydramatic/P1010038
I do have a flywheel and all the fluid coupling parts, which I think are identical to 53 Olds. The flywheel is 14.5 inches and 145 teeth. The bellhousing I have is for Nash 6-cylinder only, so I will need a different bell.

Questions:

1. I believe my best bet for compatibility is a 53-56 Olds motor with a 53 Olds hydramatic bell. As I understand, the 54-56 Olds hydros were slant pan (rotated), so I assume the bells would not work for my flat-pan. But the motors should all bolt to the 53 bell, right? I think I would need a 53 starter because Olds changed the number of teeth in 54 (I need 145). I think the 57 and later Olds motors were externally balanced so that would require getting my hydro flywheel balanced to the crank, and I’d prefer to avoid that. Would earlier (49-52) Olds motors & bells work also?

2. Next choice is 52-55 Cadillac, which I believe used the same 4 speed dual-range hydramatic. I have never seen one so I don’t know if this is flat or slant pan. Does anyone know? Were the motors internally balanced? I am a Cadillac ignoramus.

3. I have never seen a ’53 Olds hydro bell in person. I think this photo shows one (being prepped for a B&M hydrostick): http://www.rodnkustom.com/rocketeers/hydramatic/HotRodAnnual.1961-010.jpg
Can anyone confirm this?

4. I assume that the bellhousing for a Jetaway trans (56 and later Olds) would NOT work, since the Jetaway was a completely different animal, but I don’t know for sure.

5. Of course, any original B&M Hydrostick adapter kit (combined with an Olds bellhousing) would open up more options, but these are impossible to find.

I also investigated Chevy (some light trucks up to 62 used the hydramatic), but it turns out the whole fluid coupling mechanism (and bellhousing) was smaller than the standard Olds setup and the input shaft was different too.

Thanks for reading all the way down!
D.O.N.

 

As I understand it some clutch packs and gear ratios varied but for the most part they are all inherently the same design. If you use Cad/Pont/Olds flywheel/torus assemblies you use the "big" assemblies (looks like the # of retaining bolts for the torus assembly is the same for your Nash);if you use the Chevrolet truck then"smaller" assemblies are used ( 18 blots to assemble torus assembly. I think the input and front pump is the same. I would say use the Chevrolet assembly, but the real problem there is going to be finding the correct starter; they were a one off, one purpose starter. They were mounted "upside down" in that they were rotated so the solenoid was on the bottom; the real difference was in the nose of the starter. That starter will be almost impossible to find. If I'm wrong here someone else will jump in. BUTCH.

 

you probably won't like what i have to say,but i don't think you wanna use any of the old Nash driveline parts.

it's the same hydra-matic,but internally it doesn't have enough clutch plates to hold up behind a V-8 and as far as keeping the old torque tube rearend,i don't think that would last very long either.

does the Nash hydro mount at the bellhousing?

also,does the Nash engine have a rear sump oil pan?

if so,just swap in a complete 303/hydro from an Oldsmobile.

and a beefier rearend.

 

You're right, I didn't want to hear it but I'm leaning that way anyway. The differential is probably tough enough to handle a mild V8, it is the same one used with the V8 Ambassador (Nash used Packard 320 motors in some). But if I go to an open drive shaft, I will need something else.

Thanks, a complete 303 drive train swap sounds like the best idea. The Olds hydro should bolt right in, I just have to figure out the motor mounts and rear end. My hydro does mount at the bell, but the current pan is not a rear sump. I will have to deal with moving the steering linkage a bit if I go with an Olds motor, but I knew that before. Is it possible to use a different pan with a 303? (maybe fabricated?). I'll be doing more thinking and measuring before I try to find anything.

Thanks for the input!

 

I am pretty sure the Pontiac was the only car that used the slant pan. Olds, Lincoln, Willys, Nash, Cadillac, Chevy trucks, Rolls Royce, etc., etc., etc., all used the flat pan for the duration. It is true the Nash has fewer clutch plates but that is easy to fix. Just machine the pistons the thickness of a clutch and disk and drop in another pair. Problem is they also had 3 pinion planet gear clusters whereas the big car trannys had 4 so that needs to be fixed. If you can find all the parts to upgrade you can still use the tranny, it is fine otherwise. Oh yes, and lose the tail housing and find one for an open drive line. After seein all the mods you need to make, would be worthwhile finding a good core w/ all the right stuff in the first place. Don't give up on the Hydro though, it's a great machine. There are a couple of guys selling or giving away Hydros on this board.

 

man must be the Hydro-season. never seen so many different posts on my favorite tranny

 

To set the record straight--

Pontiac used the slant-pan in '55, and also in '56 wherever they used a Dual-range Hydramatic instead of the Controlled-coupling Hydramatic. All other years of Pontiac's (with auto tranny) from '54 on back used flat pans (Single-range up through '51, and Dual-range thereafter).


Olds used the slant-pan from '54-5, and also in '56 wherever they used a Dual-range Hydramatic instead of the Controlled-coupling Hydramatic. All other years of Oldsmobile's (with auto tranny) from '53 on back used flat pans (Single-range up through '51, and Dual-range thereafter). Except for some '53 Oldsmobiles that used Buick Dynaflow's that got installed after the Hydramatic plant burned down.

All other Single-range and Dual-range Hydramatic applications used flat-pans, though a few heavy-duty versions may have had different configurations (I saw a transverse-mounted unit in the back of a mid-'50's tour bus!!)

 

I've got that Cal-Hydro that I'm not going to use if that helps ya or anyone else.

 

Have sent you a couple of PMs, wont acept anymore, came back as your box is full, you prob know it, but would like some info on Olds from you. Thanx, Dave

 

Daveydeuce, I rarely use the PM system. E-mail me direct at [email protected] instead.

 

I don't want to open another Hydro thread, so I ask here. What tranny fluid should I use in the Hydro? It's from 1948, if this matters.