One Ton Differential Gearing

[Farnuckel]

Help Please! I have a 57 Chevy 3600 (3/4 Ton). In the past, it has had a one-ton axle put under it. The gear ratio is Super slow. I have a granny low in the transmission to get me moving, so I wanted to change the gearing. Where do I go to find a ring and pinion for this 1-Ton Axle? Should I just find some other complete axle assembly with hopefully the same hub face width and torch the brackets and mounts and fab it into my truck? Sounds like a hassle either way.
Thanks

[mr48chev]

A complete axle assembly would be a whole lot simpler and probably less expensive in the long. Plus you can sell the axle you have now to recover some of the cost. If it has single rear wheels you might look into a late sixties or early 70's rear axle as they can be found with 3.70 or 3.55 gears fairly easily With those You probably want to look at GMC axles as they usually had leaf springs rather than the coil springs the Chevys of that era had. If width isn't a real issue you could even use a mid 70's axle that while a tad wider might be a lot easier to find.

[dwcsr]

I would call randys ring and pinion. www.ringpinion.com they would be able to tell you if its viable to do and if they do make something like that

[RanchTruck]

Is the axle in your truck set up like a ford 9" with the removable cast center section of the differential bolted into a welded steel housing? It's probably a Ho72 axle then. They are really rugged, but 4.56 is the most common ratio. 4.11's are the best that came factory I think. 5.13 on the low end.

I think it has a 63" WMS, so there's a lot of newer axles that will share that but you may have to move spring perches and shock mounts.

You could also go the route of an overdrive transmission.

[Farnuckel]

mr48chev: I'm leaning towards a complete axle swap. Unfortunately, the width is very important. I have a toolbox bed, like a county truck, made by McCabe Powers, quite rare. 1" wider, and my tires will hit the box, 1 or 2 narrower, and I'll hit the frame. Thanks for the suggestions on finding a suitable axle and gearing.

dwcsr: I will look into that, thank you

RanchTruck: It has a removable front And rear, if I remember correctly. The 3/4 ton has 4.57 gears. This one-ton axle has 5.23 or something according to a factory 57 owner's manual. I don't have it on me at the moment. Either way, even 4:11 gears would be an improvement, but I'd like to get under 4.00, however that works out. The U-joint connection concerns me. I need to be able to get a U-joint to hold it all together.

[studda]

Originally Posted by RanchTruck

4.11's are the best that came factory I think. 5.13 on the low end.

Lucky. My '53 has a 7.09:1 granny low first gear and a 6.17:1 final gear. It also came from the factory with an 85hp 216 in it so now it's probably even lower than that.

http://chevy.oldcarmanualproject.com...r/57tom100.htm
According to this, you are correct that the 3/4 ton had 4.57 gears. If you go back one page, it looks like the 1/2 tons were built with 3.9 gears. The previous page also has tranny gear ratios.

[ChevyBrad]

I swapped in a dana 60 with 4.11 gears in my 1 ton, but it widened my wheel mounting surface 2 inches on each side. Still happy with the results though.

[Farnuckel]

studda: Any chance you wanna buy a one-ton axle with 5.14:1

ChevyBrad: My buddy has a dana he'd give me if I need it. Maybe I can find some different rims so the offset puts the tire where I need it. Two inches each side is a lot to make up though.

[studda]

Originally Posted by Farnuckel

studda: Any chance you wanna buy a one-ton axle with 5.14:1

No thank you, I'm leaving mine all original. Besides, I don't have the money to buy much of anything right now. Gotta love Christmas. You should be able to find a buyer who is trying for an all original build.

[BlueJeep]

A cab and chassis 14 bolt is 63" wide, and is available in 3.42 and lower gearing. It's what replaced the Eaton rear axle in 1973.

[fourspeedwagon]

If you decide to go the easy way--- you just need the third member from a 67-72 3/4 or one ton. They are a drop out style and in those vintages the common ratio is 411. You should be able to do it in an afternoon and you won't have to pull he whole rearend out or worry about a new width.

[mechanixman]

The highest gearing they had for the HO72 rear end was a 5.14 to 1. Next was 4.56 to 1. If you're looking to sell your rear end, people who build rock crawlers like to buy these because they're damn near indestructible.
GM used the HO72 from 67-72 1 ton trucks. They typically had a 4.11, but there were rumors of a few 3.73 somewhere out there. (I think I might have one) And like others have said, the third member just drops right in.
If you're looking for any parts for your truck, there is a place called jack's auto ranch. It's about halfway between Madison and Milwaukee. I know that's pretty far from Exeland, but it's worth the trip. This yard has everything. Last time I was there, I saw a wood frame complete with the drivetrain and wooden spoked wheels. The cap said DB as in Dodge Brothers. Before Chrysler bought the company! I've seen 16 AD trucks, and several (I wasn't really looking) task force also.
That's where I picked up my new differential.(third member)

[ChevyBrad]

Yeah I had to pull out my rear fenders about 1/2" to clear my tires but I have 265's which came on the truck. I'm definitely going smaller soon. The 4.11 replacement from the 70" truck sounds like the best option. I was not aware of that when I did my swap.