1941 Pickup transmission

[nb141fd]

Currently rebuilding a 1941 3-speed pickup transmission to eventually mate up with an 8BA flathead. My question is since this trans came out of a pickup will the ratios (15 tooth drive gear, 3.114 first gear and 1.773 second) work well with a 3.78 rear in a Model A? I believe the passenger transmission for 1941 had 16 tooth drive gear, 2.82 first gear and 1.604 second gear. Now would be the time for me to switch over to the 16 tooth drive setup if it is the way to go. Primary use will be casual street driving. TIA

Tony

[Charlie ny]

16/28 with 3:78's..........15/29 too low........imho
Charlie ny

[nb141fd]

That's what I thought Charlie. Can you tell me if I convert to the 16 tooth setup do I just replace the Drive gear and second gear or is there much more to the switch? TIA

Tony

[skidmarks]

Change the Cluster and the input . Magic number is 44

[nb141fd]

Thank you skid.

[Charlie Stephens]

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Originally Posted by Charlie ny

16/28 with 3:78's..........15/29 too low........imho
Charlie ny

Charlie ny,

How would these gears work if he changed his rear end to 3.54 or 3.27? Low gear for take off and high gear for the freeway.

Charlie Stephens

[Charlie ny]

CS,
My focus is the spacing of 1st, 2nd and 3rd....IMO a slightly long 1st is very
desirable which I think is what 16/28 supplies. 15/29 makes 1st surprisingly short
in IMO. Launching Tony's 'A' with an 8ba and 3:54's will be smooth as far as I'm con-
cerned unless he's going to run too much cam. I'm not a fan of 3:27's ,too tall with a
long stroke motor. These are my opinions only and I certainly respect any other
opinions.
Charlie ny

[alanwoodieman]

I run 28 tooth cluster in my 41 3/4 ton truck with 51 merc engine and has a 9" rear axle with a 3:25 gear set. great combo most of the time, takes some getting used to on starting up on hills. I had a 3:50 in it and think I am going back to it. 29 tooth had a very short run up in second gear, too slow to merge with traffic, 28 tooth is great for that reason alone

[Juergen]

Originally Posted by alanwoodieman

I run 28 tooth cluster in my 41 3/4 ton truck with 51 merc engine and has a 9" rear axle with a 3:25 gear set. great combo most of the time, takes some getting used to on starting up on hills. I had a 3:50 in it and think I am going back to it. 29 tooth had a very short run up in second gear, too slow to merge with traffic, 28 tooth is great for that reason alone

Can you explain the short run in 2nd? I thought I worked up all the 1st and 2nd gear combinations for a 29 versus 28 tooth gear set. The 29 tooth is lower than the 28 tooth by 10 % in both first and second. So the spread is the same. Which is why a 29 tooth trans coupled with a 10 % lower rear end than a 28 tooth has the same engine characteristics while in first or second gear. In high the engine runs 10 % slower at the same highway speed.

[V8COOPMAN]

Originally Posted by Juergen

In high the engine runs 10 % slower at the same highway speed.

In high gear, there is no gear reduction of any sort. Engine speed (input shaft speed) is coupled directly to the mainshaft (output shaft). Can you explain the 10% slower you speak of at highway speed? DD

[Ross F-1]

For comparison, 48-50 8BA pickups with the light duty trans had 2.82 1st with a 3.73 axle. In 51 they changed to a 2.78 1st, with a 3.92 axle.

I have a 9" rear in mine, and have tried both 3.25 and 3.50 gears in it. The 3.25 required too much clutch work to get moving, and was a dog accelerating above 50 mph. I've been running the 3.50 gears and it is about perfect IMO. The only time I've had any problem was in stop and go traffic on the side of a steep mountain road, my clutch got mighty hot.

Are '41 pickups open drive?

[nb141fd]

OK, I've decided to go for the 16 tooth drive gear setup and the 3.78 rear end. From what I can deduce in the Van Pelt book I will need a 8M-7017 main drive gear (8.25") to replace my current 022A-7017 (8.20") drive gear. I will also need the 8M-7113 cluster gear to replace my current 022A-7113 cluster set. Is that all there is to it or do I need to replace other components? According to Van Pelt it seems that my current second gear also fits the 16 tooth setup. Thanks for any help you can offer.

Tony

[Charlie ny]

Tony,
The 16t input main gear and 28 t cluster will get you squared away. If you
are not in a big rush keep in mind when you purchase individual gears they can be
costly while complete transmissions are sometimes pretty cheap.
A trouble free rebuild involves a few seemingly insignificant details that
when overlooked will bite you.
Charlie ny

[nb141fd]

Thanks Charlie, appreciate the info. Boy are you right about prices on gear sets. I have a 1950 3-speed column shift that I was hoping to sell outright, but I just might cannibalize it for the 1941 box.

Tony

[Charlie ny]

Tony,
Be careful some gear sets will interchange....sometimes '49 and '50 Merc...
and some will not. Take a look at the 1st and rev slider gear for tooth geometry
and if the same count the teeth. Even if the same some later clusters have loose
needle bearings vs the roller skate roller bearings.
Charlie ny

[alanwoodieman]

40 up 3/4 ton and up are open drive line

[rotorwrench]

Mercs used the same gears & case from 1949 thru early 1951 (near February 1951) after that they changed to the late gears and 4-bolt Borg Warner bolt pattern.

The 15/29 gearset would work OK with the 3.54:1 rear axle in a light body model A. I'm going to try them out anyway.

[35fordtn]

I personally prefer the 29 tooth cluster in my cars, as we live in a area with steep hills and many times traffic lights right in the middle of the incline.

[scooder]

I fully agree with Charlie, Little Model AV8 with 3.78 rear, the 28 tooth set is just about perfect. I also much prefer a slightly longer first and second you get with a 28 tooth set over a 29.
Martin.

[Juergen]

Originally Posted by V8COOPMAN

In high gear, there is no gear reduction of any sort. Engine speed (input shaft speed) is coupled directly to the mainshaft (output shaft). Can you explain the 10% slower you speak of at highway speed? DD

What I wrote is that the wide ratio trans coupled with a 10% lower numerically rear end lowers engine speed by 10% in high (direct) gear (while having the same engine speed/torque in the lower gears).