VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 36 Differential help

A long time member told me he had a spare 3.55/1 gear set from Patricks he would sell me for my 36 Town Sedan. He unfortunately passed away before we could complete the transaction. Now his daughter and some other club members are finishing cleaning out the garage. They found one set that has that ratio but no tags identifying it. It does have a part number stamped in it. Does someone have an old catalog from Patricks that might list part numbers? In the photo she sent I can see some of part number and it ends with 8620 and has 11/39 stamped after it. The daughter says something about a pick up. If I remember correct the 36 car is the same as the 36 to 39 pickup.Am I remembering correctly? Thanks - Art

The truck is the same as a 1936 MASTER

Are you sure it was for this model? I am not aware that that a 3.55 ratio was ever made for this year.

I agree that Chevy never offered a 3.55 gear set in that time period.

There are some 3.55 gear sets available on the aftermarket. Most of the ones that I see for sale are for 1940 and newer. I also know that a lot of people have adapted early 50's Powerglide rear axle gear sets to earlier cars and trucks.

What the person actually has is hard to say.

A vendor, possibly Patricks, did once have 3.55 gears listed for 1/2 ton back to 1940 and back to 37 with "driveline modification". It can't really be. See my post here for details: https://vccachat.org/ubbthreads.php/topics/401496/re-1937-chevy-truck-rear-end.html#Post401496

I am fairly certain the gear set you want (3.55) does not exist and never existed. I would love to be proven wrong though. Let us know what you figure out.

Interchangeable rings and pinions for 36 Master are:

Later 35-36 Master
Later 35-36 Pontiac
Later 35-39 Chevy 1/2 ton.

Existing gear ratios, low to high:

4.89 Pontiac "Mountain" gears. Maybe a rare Chevy option (?), one bearing different.
4.55 Pontiac default 8 cyl.
4.44 Pontiac default 6 cyl.
4.11 Chevrolet default, Pontiac "Plains" gears
3.82 Chevrolet "Fuel Economy" gears (rare)
3.32 Larry Jackson, aftermarket, modern era, very few sets made.

I think that list is complete, but if anyone knows of others, please post.

If it does turn out to be a gear set that is a sought after ratio, it might be worth seeing if multiple people would pay to get it reproduced - both car or truck. You could end up with yours for free and help a bunch of guys out...

Going back 15-20 years ago I thought there were 3.55 produced for both cars and trucks of varying years. Recall something about needing a 50's torque tube/axle for a starting platform for the ring/pinion and then transplanting into the older vehicle. There is a document floating around that Ray from California put together when he put a 3.55 in his 1936 truck. Sounds like recently he may have lost his home in the fires in the late summer unfortunately.

Ray's method is in my opinion the easiest way by far to get 3.55 in a 1936. Ray's detailed instructions are elsewhere on this site. His handle is brino.

In short, you start with a 1937 CAR (not truck) axle housing, axles, and brakes. The 1937 up CAR axle is a hypoid design slightly smaller than the 36 1/2ton or Master.

You relocate the "keys" on the axle that allow it to turn in it's mountings, further in for the narrower 1936 spring spacing. This gets the 1937 housing (and axles and brakes) mounted in the 1936.

Then you use gears and a differential housing from an early 50s Powerglide CAR. You use the 37 CAR torque tube and carrier, cutting and rewelding it to get the 1936 length.

Then you shorten the 1937 CAR driveshaft, removing the splined socket at the back where the pinion attaches, and weld in the splined socket from the Powerglide car, because the Powerglide 3.55 pinion has a different number of splines compared to 1937.

There are other ways, but they are probably quite a bit more work and expense.

As far as I know yes this is one of those sets from 15 to 20 years ago that Patricks had manufactured by another vendor. Wally put one in his beautiful 36 3 window coupe, and had bought a second set for another project. I think he decided he would never get to the other project and sold it some time back. At the NW Mini Meet in Albany OR 2018 he told me he still had the other gear set and would sell it to me for our 36 Town Sedan. He was going to look for it in his garage but time ran out. I think it would improve the driveability of the 36. I'll tell you those 2 36s side by side were a pretty sight. I will see if his daughter can send me the rest of the part number on the pinion shaft. Art

She found the installation brochure for it. It is a truck gear set from Patricks. He put the other gear set into a 40 to 54 Chev/GMC truck rear end and installed that into his car. I told her I would still like to buy it, so I guess I am looking for a 40 to 54 truck rear end again.
Art

I don't know for sure (someone here probably does), but I think by 1940 the track width of the truck had increased quite a bit. That would leave you needing to narrow the 1940 truck axle housing and axles. If so it would probably be a lot less trouble to do the trick with the 37 car axle housing, and use car gears. Best of luck whichever way you go.