The Stovebolt Site Forums The Shop Area General Truck Talk 3 Speed Transmissions?

I have been looking at a lot of 38-47 first series trucks lately and noticed something interesting. I have not seen any that actually have the three speed snycromesh that is supposed to be standard for the 1/2 and 3/4 tons according to all the literature.

How is that every truck I look at has the 'original' four speed if the 3 was standard and th4 was the option? Just to qualify this, mine has the 'original' 4 speed as well.

According to some old timers I knew who drove these trucks when new, I was told that none of the trucks they drove had 4 speeds and that mine couldn't possibly be original.

Is is possible that the 4 speed was more popular and therefore ended up in more trucks than the standard?

Any thoughts on this?

i have a three speed

have seen both 3 and 4 speeds. some 3 speeds were still column shifts some had been changed to floor shifts

My '41 half ton is a 3 speed also. Previous owner said that it pops out of gear though. One more thing to fix or replace.

John

Tim - Your post and peek at your website made me reread my 1939 shop manual. Since it shows the gear shift on the column in the diagram, I didn't realize until now that this was the new option for the 39 passenger car only, and the standard was still on the floor.

Is your three speed snycronized? While I like having the low first gear, 7.23 to 1 is really a very limited gear option with today's roads and double clutching in a driver truck makes life very interesting at times.

It leaves me wondering though why all the trucks advertised come with the 4 speeds. Of course I guess I shouldn't wonder too much. There is a 40 on Ebay listed as a 1939 and after I told the seller the listing was incorrect they replied that "You must really enjoy these old trucks" without fixing the listing. Go figure.

What year did the trucks go to column shift on the three speeds? I thought the truck 1947 three speeds still had the floor shift, even though column shift was used on the 1940 Chevy cars.

The 4 speed didn't get synchros until 1947 AD series, so if those trucks don't have the little reverse lockout lever they aint the original transmission.

The trucks I have seen from this era had both three speed and four speed transmissions. Most of these trucks were work trucks, and so many of them that here in the Colorado mountains worked here on ranches or in the mines or what ever had a four speed. I have seen some that were delivery trucks for local merchants that were three speeds. Both the three speed and the four speed had the stick on the floor, and the four speeds had the little lockout lever on the stick.
These trucks were work trucks. We had passanger cars for travel and recreation. The role of the truck has completely changed today.
Jim

i have one with a 3 speed they are very small mayby not as beefy as a 4 and mayby dont hold up time tells mayby most are gone

That brings up another question. What year did the lockout for reverse on the four speed appear? I've heard it refered to as sling-shot reverse as well.

On the floor shift for the three, am I correct in thinking that the shift pattern was the standard H, with reverse where fourth would be? Also, does the three speed require that you bang your knuckles on the dash when shifting into first?

Mine has the lockout lever, but is definitely not snycronized as my (only occasional .... ) grinding of gears attests to.

The shift pattern for the three speed on the floor is the same an the three on the tree. Reverse is straight up toward toward the dash where first is on a four speed then first is straight down where second is,then second and third are like third and fourth on a four speed.
Jim

My guess would be that in the '30's and '40's, people were buying trucks to use them as.. well.. trucks.

A truck back then wasn't a status symbol, and people didn't buy a truck to 'look cool' or because they were trendy.. they bought a truck because they needed a truck to do truck type stuff.

So while the three speed might have been the 'standard' configuration, more often than not, your typical truck buyer of the day was going for that 4 speed 'option'.

In fact, it's pure marketing genius that can still be found in new vehicle sales today.

You advertise the vehicle as 'standard' or 'base model' at a low price to get the customers in the door, then tell them.. oh yea.. by the way.. if you want silly things like HEAT you're going to have to pony up for the 'heat' option.

Ohh.. planning on using it as a real truck? Well for a couple bucks more you can get the 4 speed option!

That kind of thing.

Same goes for the '47 thru '53 trucks.. the '5 window' was supposed to be an 'option' but I see way more of those on the road than I do three windows.

It was just a popular option.

Up here and in Alberta (where I have personal experience) 1/2-ton trucks were bought as personal transport/light duty trucks by farmers with the 3-speed, while heavier trucks were spec'ed with the 4-speed routinely - even though the 3/4-tonners were available with the 3-speed - because you ordered the heavier truck for "real" work. The wife took the 1/2-ton to town for parts or groceries while the men did the real work. Okay, girls, I'll pull my tongue out of my cheek now so you can plant one on me if you like. Hell, this is how we used to think, and you know it. We were conditioned. But we're free from that now. Aren't we?

I have 2 1939 1/2 tons with the orginal running gear in them. One has the 4 speed and one has the 3 speed. The 4 speed was used as a highway truck the best that I can findout. The 3 speed was a ranch truck. One would assume that what ever was available was what was used.

I find the 3 speeds have a little better 'highway' speed.. the 4 speeds are geared really low, with 1st geared so low, it's next to useless unless your pulling stumps or a tractor out of a ditch.

The "highway" speed would be the same with either as that is determined by the differential ratio and was the same for either. The ratios of the second and third speed of the fourspeed was close to the first and second of the threespeed, with high gear of both at 1:1. The threespeed was friendlier due to synchros on the top two gears.

Straight out of my 39 Shop Manual

3 Speed

First 2.94 to 1
Second 1.68 to 1
Third 1 to 1
Reverse 2.94 to 1

4 Speed

First 7.23 to 1
Second 3.48 to 1
Third 1.71 to 1
Fourth 1 to 1
Reverse 7.15 to 1

I've used first only twice seriously. Once to pull a stump. It required one 'pop' of the clutch. The second time I hauled a load of bricks out the basement level of a commercial building site up a 25% sand ramp.

Looking at these numbers it does look like the 3 speed is a little more street friendly with its slightly different 2 and 3 ratios. Never realized until now how much difference there was in the reverse as well.

Ive got a 3 speed in my 50 1/2 ton

I had a 46 before my 50, and that had a 4 speed in it

In 1948, Chevrolet trucks went to a redesigned three-speed transmission with a column shift and shift-linkage attached to case side. In 1948, the parking brake changed to being activated by a pedal through the left side of the floorboard. Before 1948, the parking brake was activated by a lever next to the floor-shifter.