VCCA Home Forums TECHNICAL - GENERAL Trucks and Vans 1955 Suburban Auto Transmission

A poster on the AACA forum is looking for everything he needs to convert his 1955 Suburban chassis short bus from a manual gear box to an automatic. An ankle injury is forcing the issue. He has been told he might be best to find a parts truck with everything he needs to convert. He wants to keep the 6 cylinder intact. They believe he needs a Dual Range HydraMatic.

Any suggestions on this conversion and where he might find the parts needed?

Thanks

Dave

This would be a rare conversion.
Finding a parts vehicle sure wold be advised.
There were actually three diferent versions of the trans. The 1/2 ton, 3/4 1 ton, and 1 1/2 ton all used different intermeadite gear ratios.
For normal driving it would go thru all four gears. For city/hills there gears 1st, 2nd, and 3rd. In the 3rd position woudl start in 2nd shift to 3rd and if floored would drop down to 1st.
It was not considered a Dual Range although it was close.

On a 1/2 ton the drive shaft is the same. for a 3/4 or 1 ton the front drive shaft is different.

A cooler is used on 3/4 and 1 tons.

Like Gene said, not an easy conversion. I did it for my 54 and had the advantage of buying a rolling chassis. The frame was different as it incorporated heavier crossmembers under transmission that un-bolted to remove transmission from under the truck. Brake lines were routed differently to clear transmission for same reason. There was a different transmission cover and hole in cab to give access to "bellhousing bolts". There is all different linkage, shifter, neutral start switch and detent assembly, an electric starter, electric choke, drive shaft length...Not only that, GMC and Chevrolet linkages and shifters are completely different so you have to find a parts truck from correct family. 55 2nd series would be different from my experience but I was sharing "what I know". It is not an impossible swap but there are more differences than you might expect.

Gene and Greg, Thanks for the info.

Anyone know where he might find one of these parts trucks?

Dave

A Hydramatic shift lever and interior fittings connected to a Powerglide transmission might be a more practical solution. His foot pedal for starting will need to be changed to a switch activated starter. There will be other alterations but still maybe simpler than finding and swapping out all the stuff for the Hydramatic. Good luck to him.

Mike

I agree

Thanks guys, I will pass this link on to him.

Dave

Thanks all.

I'm the rocket scientist undertaking this project. There is no big hurry, as the bus is just now beginning its arduous journey through the first stages of body prep and overall rehabbing. I assume that I may have to put it back together with the manual transmission until I locate the other unit.

But if anyone knows someone with a pile of old Chevy 1.5 ton trucks sitting around .... it is the 4100/4102 series. 1955, second series.

I'm hoping in time to turn up the right donor, and not create a new song for Johnny Cash by making it into a Frankenstein.

The Chevrolet hydra-matic/powerglide shifter will bolt on to a 3 speed on the column steering column. There was an ad on 67-72 chevy trucks site listing "most of" a powerglide column for sale. https://67-72chevytrucks.com/vboard/showthread.php?t=802629

Marty,
Chevy trucks, from your era, with Hydramatic transmissions are extremely rare. This applies to all sizes but especially when you depart from the 1/2 and 3/4 ton models.
I suspect that a number of trucks, originally equipped with the automatic transmission, were converted to 4 speed manuals transmission at the first sign of trouble with the automatic. Parts for this conversion would have been readily available and affordable during the working lives of the trucks.
You have not told us what engine you are using. A "modern" automatic transmission mated to your engine will be hidden from public view and give the convenience you desire. To make the authentic conversion, a complete parts truck will be a MUST.
Good luck with your project. Keep us informed on your progress.
There are some YOUTUBE guys who rescue old Chevy and GMC trucks in the Northwest. Classic Truck rescue and Elderly Iron, I think. They might be able to help.

Mike