The Stovebolt Site Forums The Parking Lot Big Bolts 1950 4100 axle

Can anyone tell me what axle is under a 1950 4100? Is it true you can swap out center section with a ho52 or 72? I want to keep original wheels and axle (brakes have been done) i just want to find a way to cruise at 55 mph without being almost wide open. I've posted before about a axle swap but would rather see what my option are. Thank you

Here's the info from the 1950 Truck Vehicle Info Kit. I have no idea whether an HO52 or HO72 would bolt in. I'm sure one of our big bolters will come along with more info.

The 4000 series has a MUCH heavier rear end. No, the 3/4 or 1 ton axle parts will not interchange. You will need some sort of heavy duty 5 speed transmission with overdrive on 5th.gear to get more highway speed, or install an auxiliary transmission like a Brownie or Spicer with an OD top gear. Be sure to make upgrades to the brakes and steering to make sure your vehicle safe for the rest of us who have to share the road with you!
Jerry

You will likely need to replace the entire rear axle to obtain a gear ratio that will give you your highway speeds, likely one off of a c50 or 60.

Another thing to consider is the reason the axles had such a low ratio in the first place; It was to deal with the lower power output of the motors of the era, which was why V8 engines on big bolts were such a big deal back then. You could swap out the rear axle from a motor home fairly easily, but then the anemia of the engine's acceleration will make itself apparent.

I have completed the axel swap to a higher ratio from a Motorhome. The axel I used is a Dana 80 from a 1990 GM chassis, it has a 4.88 ratio. My axle has a 10 x7.25 bolt pattern with disc brakes, these were also available with drum brakes. My top speed is about 62 Mph @ 2800 RPM.

Farmer Petry, according to the GM heritage site, a 2 speed axle was not an option for the 1-1/2 ton trucks. I was fortunate enough to find from one of our big bolt members a 2 speed pumpkin for my 2 ton axle. You could consider swapping in a complete axle from a heavier truck if you're planning on loading the truck heavy. Or, with the largest diameter drive tires you might be able to achieve your goal with the axle you have. My experience is this, my original gears were 7.20 :1, with the 2 speed pumpkin I now have 6.40/8.20 or there abouts. With 42 inch diameter drive tires my truck can hit 65mph, that is wound out against the governor at 4000 rpm.

Thank you everyone. Sounds like a axle swap might be in my future. The truck will never be loaded heavy. Thought it would be fun to run to home depot once in a while and still keep up with traffic. If I found a dana 80..10 lugs 7.25 would my stock wheels fit?

My 1958 Chevrolet 4400 had a 5 x 7.25 front and a 10 x 7.25 rear. The same wheel fits front or rear. I opted for a 19.5 wheel to be able to have more tire options.

Late 5/10 on 7.25” wheels and axles have a larger hub diameter, so modern tubeless wheels fit, older tube type wheels do not fit.

Ed

If you're gonna drive the rig, modern tubeless tires are a much better option. Cheaper to buy, any shop can work on 'em, you can get radials. Makes a big difference. Plus the smaller 10 bolt pattern is pretty common so used wheels are available at any time, vs. the two ton Chevy large diameter 10 bolt pattern, which is not common and the wheel upgrade there is more expensive. But still worth it.

Tronman,
Tubeless wheels with 10 on 7.25” bolt pattern are getting really rare around here and in adjoining states. If you can round some up, might be able to help someone out. I got some 10 on 8.75” 22.5” wheels I redrilled to 10 on 7.25” to fit my ‘55.

Ed

Here are the 19.5" steelies https://buytruckwheels.com/products/19-5x6-hub-pilot-dual-10-hole-p-300-chevrolet-or-gmc-typical

Here is the preorder for the 22.5" size https://buytruckwheels.com/products/22-5x6-75-white-steel-10x7-25 (Note - these show as currently out of stock)

So they can be had. The 19.5" are even genuine Accuride. Which is probably why they weigh 40lbs instead of 90lbs. It's a big expense for Bolters like us, but hey at least you only have to do it once, and then you got modern wheels and tires you can actually buy, forever.

The 19.5's I have are from a 1990 GM Motorhome. I paid $250.00 for the entire Motorhome. I kept the Dana 90 axle and wheels, I sold the transmission for $700.00. With the money I made I bought the new radial tires

Perfect!!