54 hydramatic in a 55.1

[55.1stSuburban]

Hey, guys. Was hoping to get some help in swapping a 54 hydramatic pickup transmission into a 55 first series Suburban. Is this doable?

 

[Bill Hanlon]

Depends on how many of the hydramatic parts you have from the 54.

Does the H-M work well in the 54? They are EXPEN$IVE to fix and finding someone with the proper tools and knowledge has only been getting harder to do since the 1960s. Don't settle for anyone that still has all his teeth.

Do you have a complete 54 truck with Hydra-Matic? If so, the only thing you'd have to fight would be the second frame crossmember, which varies from stick to Hydra-Matic. I don't have 55.1 parts manuals, but you would be about 90% right assuming a 54 crossmember would fit a 55.1 frame.

Some 54s had a torque tube. None of the 55s did. Is your 54 hydramatic torque tube all the way from the tranny to the rear end?

... plus a lot of things I've left out.

 

[55.1stSuburban]

Depends on how many of the hydramatic parts you have from the 54.

Does the H-M work well in the 54? They are EXPEN$IVE to fix and finding someone with the proper tools and knowledge has only been getting harder to do since the 1960s. Don't settle for anyone that still has all his teeth.

Do you have a complete 54 truck with Hydra-Matic? If so, the only thing you'd have to fight would be the second frame crossmember, which varies from stick to Hydra-Matic. I don't have 55.1 parts manuals, but you would be about 90% right assuming a 54 crossmember would fit a 55.1 frame.

Some 54s had a torque tube. None of the 55s did. Is your 54 hydramatic torque tube all the way from the tranny to the rear end?

... plus a lot of things I've left out.

I have a working 1954 hydramatic with all of the parts.

So not all 54 trucks were closed torque tube?
Not all 1954 1/2 tons had same type torque tube?

I have to find a 2nd crossmember to hold the tranny in place?

thank you,

 

[Bill Hanlon]

Do "all of the parts" include things made from UnObtainium like ...

... throttle linkage all the way from the pedal to the carb and then back down to the tranny?
... shift linkage all the way from the shift knob to the tranny including the neutral safety switch?
... a steering column for the HM?

I have the serial number break in '54 for GMC 1/2 ton trucks for closed driveshaft to open, but I don't have the same for Chevy trucks.

What is the reason for wanting to change to the HM? If it is just to get an automatic tranny it might be easier and cheaper to change to a TH350, TH400 or 700R4 (overdrive) tranny.

 

[55.1stSuburban]

Yes, have all the parts from a functional 54.

I want to stay “period correct”, so upgrading to a more modern tranny is not an option.

So i need to remove 2nd crossmember too huh?

The Chevys didn’t break until 55.

 

[Bill Hanlon]

So i need to remove 2nd crossmember too huh?

I believe so. I am basing this on 39-54 GMC Master Parts Book which has a separate part number listed for "Frame Cross Member - Second" specific to Hydra-Matic equipped trucks. Same listing says "see 8.0110 for end". 8.0110 Engine Support Bracket lists Hydra-Matic specific left and right brackets riveted to the frame. Maybe Chevy did it differently, but I wouldn't bet my life on it.

 

[coilover]

Lots of machining to convert a torque tube trans to accept an open drive shaft. Would be easier to put the entire 54 tube set up onto the 55.1 but it would not be a bolt in. If the spring length and front I-bolt and rear shackle brackets are at the same spot on both frames it would ease the install a bunch. The 55.1 springs have the spring center bolt center 1.5" forward of the 54 since the torque tube spring mounts are the "rocker type". All in all a real can of worms that is exactly backward of the normal tube to open shaft install. A huge step backward in available gearing by using the torque tube. IIRC the auto rear gear was more cruise friendly than the 3.90 manual trans gear. The 54 Hydramatic starter is pure gold in ANY condition. I bid $900 on auction site on one that finally went for $1200. Here is a 54 235 and Hydramatic the Volkswagon resto shop did that set outside till it finally seized up and was sent to the scrap yard. Everything in and on the engine was brand new as was the trans. All for the lack of a starter. I offered it for free on this site but no takers.

 

[coilover]

Forget all the above. My brain slips into neutral sometimes and forgets past lessons. GM did all the work for you---just get a 3/4T set up which is torque tube at the front and open in the rear.

 

[55.1stSuburban]

Forget all the above. My brain slips into neutral sometimes and forgets past lessons. GM did all the work for you---just get a 3/4T set up which is torque tube at the front and open in the rear.

i have the electric starter switch for the dash. Yes, very hard to find.

Can you elaborate on the 3/4T setup? What did it come on? Thanks in advance

 

[55.1stSuburban]

Also/again, there’s a guy named Gene that makes these:

 

[Bill Hanlon]

just get a 3/4T set up which is torque tube at the front and open in the rear.

3/4 ton (like my '52 GMC 152) has an enclosed driveshaft at the front that went less than half way towards the rear axle. At the half way point it has an exposed U-joint connecting to an open driveshaft that feeds another open U-joint connected to the input of the differential. Also at the half way point is a hanger attached to a frame cross member (probably have to fab that) holding up the shaft where it comes out of the enclosed tube.

 

[vwnate1]

I think you're on to a *very* good thing ~ many years back a buddy of mine chanced upon a nearly all original 1958 Chevy Task Force Panel truck with 235 and Hydromatic Drive .

It easily went freeway speeds of 65 MPH without over taxing / over speeding the engine .

You don't post where you're at but IMO your best way to proceed is find a Hot Rodder who has an original project truck and buy the entire chassis including steering column , it matters not if it runs as long as the tranny is still assembled to the chassis as that's where you'll get stuck : looking for little unobtanium fiddly bits .

In the 1990's before they gave up Memory Lane auto wrecking in Sun Valley, Ca. had two Hydromatic equipped 1/2 ton pickups that were bare shells apart from the 235 & tranny , driveshaft and rear end .

Rigs like this still exist and the cheapest way is to buy a complete chassis, pitch a bitch about no cylinder head on the 235 but grab it if you can find one .

These are seriously overbuilt transmissions, used in tanks in WWII and many thousands of light and medium duty trucks afterwards .

 

[55.1stSuburban]

3/4 ton (like my '52 GMC 152) has an enclosed driveshaft at the front that went less than half way towards the rear axle. At the half way point it has an exposed U-joint connecting to an open driveshaft that feeds another open U-joint connected to the input of the differential. Also at the half way point is a hanger attached to a frame cross member (probably have to fab that) holding up the shaft where it comes out of the enclosed tube.

View attachment 25643

ah, so to be clear, your saying find a Drive-Line from a 3/4 ton truck?

 

[55.1stSuburban]

Lots of machining to convert a torque tube trans to accept an open drive shaft. Would be easier to put the entire 54 tube set up onto the 55.1 but it would not be a bolt in. If the spring length and front I-bolt and rear shackle brackets are at the same spot on both frames it would ease the install a bunch. The 55.1 springs have the spring center bolt center 1.5" forward of the 54 since the torque tube spring mounts are the "rocker type". All in all a real can of worms that is exactly backward of the normal tube to open shaft install. A huge step backward in available gearing by using the torque tube. IIRC the auto rear gear was more cruise friendly than the 3.90 manual trans gear. The 54 Hydramatic starter is pure gold in ANY condition. I bid $900 on auction site on one that finally went for $1200. Here is a 54 235 and Hydramatic the Volkswagon resto shop did that set outside till it finally seized up and was sent to the scrap yard. Everything in and on the engine was brand new as was the trans. All for the lack of a starter. I offered it for free on this site but no takers.

View attachment 25639

I would’ve kept the thing. Now way I could see that go to scrap..

 

[vwnate1]

Agreed but there's the problem : you cannot save everything .

Evan has a large pile of takeout drivelines but no one wants them .

I keep telling those few who are looking to head straight to the Hot Rodders who routinely remove good running drivelines and have a hard time getting rid of them .

 

[coilover]

Our scrap pile now even has several sbc V8's. The circle track guys snap up the 350's but the 305's, 307's, and even a 265 are sitting out in the weather. EVERYTHING is going the LS route now. We pulled a nearly new 350 out of a woman's 1950 Ford pickup and replaced it with an LS and a sweet running 350 out of a 52 3100 that was replaced by a 435hp LS. Sign of the times.

 

[vwnate1]

The really sad thing is : those who actually DRIVE their oldies prefer the older & smaller V8 engines as they use FAR less fuel and last longer and are cheaper to maintain .

In the 1960's everyone wanted Chrysler hemi's, the resulting gas sucking monsters were all scrapped in the 1970's when no one could afford to fuel them....

As a Farmer/Mechanic I prefer simplicity and reliability above all else so I'm an inline 6 cylinder lover but all those Chevrolet small block V8's are in fact great engines, able to produce good horsepower and torque whilst giving long life and decent fuel economy at the same time .

265's were very robust as they were designed for heavy duty truck use and so didn't breathe as well as they might .

Easy as pie to put on bigger valve cylinder heads and balance to make super smooth torque masters, same as every 350CID V8 Chevy ever made ~ the vast array of different cylinder heads means it's dead easy to build up an engine for your specific needs .

Swapping in the correct crankshaft turns your old 350CID into a street ready 383 stroker, all using dirt cheap factory parts .

I'm a big fan of fuel injection these days and it's easily available to convert almost any reasonably modern V8 from carbys to fuel injection that always starts instantly hot or cold , idles smooth as silk and had no flat spots .

LS1 is nice and all but I thought the idea was to DRIVE AND ENJOY your old truck .