Rear Axle Gearing

[Paul Beard]

What is the gearing of the early "50s" Mopar rears in the cars. I know the trucks have A 4:10 are the cars the same.

[55 Fargo]

Plymouth and Dodges, had 3.73 gears in the 50s, the Chryslers had 3.54. But they could have also been ordered with 3.90 or 4.10 too. This is info that has been passed on to me recently..........Fred

[Tony_Urwin]

If you decide to go with the higher gear ratio, get the whole rear axle. The truck and car axle housings are different.

[Young Ed]

I've got a car diff in my 46 1/2 ton pickup. It swapped right in. I think anything above 1/2 tons and you'd be correct.

[Tony_Urwin]

Seems like lately I've been disseminating bad information. (Not the first time I've ever been wrong!)

I got that information from George Asche. On my last trip to George's place, he sold me a 3.73 pumpkin. I had planned to swap it into the rear axle of my truck. George insisted that I take along a DeSoto axle housing and axles because he said the truck housings were different.

I hope you are right. The brakes on my truck are great, and it would be so much easier to just swap the center section.

[Tony_Urwin]

That said, I own a 3/4 ton truck, so my axle housing may be different than yours, Ed. Do you have Hollander's information on the swap?

A tranmsission swap is my first priority, but it would make sense to do both at the same time. (Especially if I don't have to swap the axle housing.)

[Tony_Urwin]

I found it in my Hollanders (duh!) The '41-'50 1/2 ton and 3/4 ton trucks use the same axle as the 6 cylinder cars.

Thanks, Ed, that's good news!

[Young Ed]

The old hollanders are pretty lacking on truck info. Dad's got them all covering the 30s to the 70s. I think for Dodges they didnt go to the full floating axle until 1ton so you may be ok. You may have to do some exploring with this project though

[Young Ed]

Good news Tony. Now that you found that out I will tell you the only small issue I ran into. There were a couple spots on my diff housing that must have been thicker on my truck one so when I was installing the car one I ran out of threads. If I had noticed that before hand I would have made a couple more threads. Since it was already back in I ended up double washering a couple of them. So FYI may want to do a test fit and check that.

[Tony_Urwin]

I should have said they use the same differential or center section. The axle housings are different. Am I monopolizing this thread or what?

George has a bunch of larger trucks on his property, that's probably why he gave me that info.

[Guest Jerry Callahan]

I have a 1952 3/4 (B-3-C) ton "job rated" pick up with a 4 speed trans.; 1st gear being a granny gear. What do you think the rear end gear ratio is? The speedo doesn't work, but the guy I bought it from said it had a top speed of about 53 mph @ about 3600 rpm's. The gear is low; I'm thinking maybe a 456

[Tony_Urwin]

Looking in one of Don Bunn's books, it seems to say that the 1/2 ton and 3/4 ton trucks came with 4.1 or 4.78 ratios.

Should be stamped on the pumpkin if you want to get under there and degrease a little.

[Guest mjmcorbett]

I've a 1 ton '49 with 4.3 gearing. I need another one just like it. I looked at two trucks the other day, both 1 ton, one was 4.1 and the other 4.89. That was a let down and an education. I've been told that the splines are different in 1 tons than the 1/2 tons. Since it seems 4.1 is more common I may just go that route. Another thing I was told that if you change out the splines in the 1/2 to to the splines in the 1 ton that it would work. I sugest being cautious before spending much money.

Mike C.

[Phil Martin]

I tried a rearend out of a 50 ply. The splines were different from my 53 1/2 ton but I suspect the reaeend in Ply had been swapped to a later model.

[Guest Jerry Callahan]

How about the 4 speed trans. on a '52 B-3-C 3/4 ton; are the gears synchronized? I'm trying to figure out if it's the clutch or the trans. Sometimes, at a stop sign, it won't go into 1st or 2nd without grinding. It seems like it's worse when it heats up. I've got it in the shop now, but if anyone has any ideas I would appreciate hearing from you. Thanx.

[55 Fargo]

Jerry, pretty sure 1st gear is not synchronized, but I could be wrong, but 2nd should be. You may have to double clutch for a while, till you can have it diagnosed. You more than likely just take off in 2nd, anyway, grind at a stop, is your clutch fully disengaged.Fred

[Merle Coggins]

Not sure when they began using syncronized transmissions in the trucks, but there's a good chance that yours is not. Syncronization only helps with upshifts and down shifts. If you are having problems getting it into gear at a stop, you may have a clutch issue.

Also, 1st gear in the truck transmissions is a granny low and wouldn't be used normally when pulling away from a stop.

Merle

[Reg Evans]

I think 51 was the first year that a 4 speed syncro was offered. I'll have to agree that the grinding sounds like a clutch problem.

You can id a syncro trans by looking at the drain plug. If the plug is level with the ground it's a syncro. If the plug angles down it's a non syncro.

Here's a photo of that drain plug on a syncro.

[Guest Jerry Callahan]

Thanx for all of the help, guys. Like I said, it's in the shop now. I should know more this afternoon or tomorrow. I'll let you know what the verdict is when it comes in. I’m kinda thinking clutch myself. Thanx again.

[Merle Coggins]

I was just looking through my B-2 Series Shop Manual and it looks like the 3 speeds (column shift or floor shift) are syncronized, but the 4 speeds are not. Maybe that changed later on?

Merle

[Dodgeb4ya]

1 ton diff`s are the same as the chrysler BIG 145" Crown Imperial limo`s rear Pumpkin. 16 spline axles. Also on the 1/2 to 3/4 tons I think the inside differential is a "Barrel" type W/ 4 pinions for heavier truck usage. The driveshaft yokes have to be swapped between truck and car. Chrysler pumkins come in 3 mounting "gasket" sizes, 6cyl cars same as 1/2-3/4 ton trucks. 6cyl wagon and long WB cars and all 8 cyl cars up to 1950 are a little bit bigger Dia. pumpkin case to axle housing- not interchangable W/ trucks and then the BIG 145" chrysler Crown Imperial Pumpkin, even yet bigger in Dia. then the other Chrysler cars. This rear end W/16 axle splines and a adjustable ring gear thrust pad is same for the most part as the 41-55 Dodge 1 ton trucks. Although it has a thrust block inside as the truck doesn`t.

Bob

[Dodgeb4ya]

Forgot to mention, 1953 axle shafts changed to 16 spline on cars and trucks.

Bob

[Guest Jerry Callahan]

I just got some info back on my clutch/trans. problem. ('52 "job rated" b-3-c). The 4 speed trans. is not sychronized in 1st or 2nd gear, only in 3rd and 4th. The inside of the trans. looks good. My clutch was slipping because the seal on the front of the trans. was leaking. It's not back together yet, so my fingers are still crossed. I'll know for sure when I get it back on the road. Thanks for all of your help.