The Stovebolt Site Forums The Shop Area Engine Shop 1947 1-Ton Panel: Overdrive or Rear End better?

Hi,

I just bought a 1947 1-Ton Panel with a School Bus Conversion from 1953. It is a really great truck, but a little slow (45-50 mph). It has a 4 gear tranny with granny gear (which leaves 3 useful gears). According to a website, it should have a 5.14 rear end.

I saw there are overdrives as well as ring and pinion sets available. Which option is more useful? Which one can I install myself? I would like to reach 65 mph, so I do not get rear ended on the Interstate.

What should I do to the brakes to work with the new speed? Currently they pull in a different direction each day, but work well.

Thanks,

Andy

I'd go with a set of 4:11 gears from a late 60s truck. Overdrive trans would be pretty pricy plus you'de need a really heavy duty unit in that bus. You could ad a power brake unit to your existing brakes for better stopping. Keep it simple and don't try to set any speed records with that big truck.

Any replacement transmission will cost a fair amount. It would likely be cheaper to go with a replacement gearset from Patricks.

My 1 ton panel had the 5:14 rear when I got it. I swapped out the pumpkin for one with a 4.10 and swapped in aT-5 from a Camaro with the proper clutch swap, too. I have put 17,000 miles on this set up with no problems so far. I have hauled some pretty heavy loads of blacksmithing equipment on some 5-800 mile trips. It is powered by a 261 engine and to be honest I almost never go over 60mph and don't do jack rabbit starts. Search the forums on the brake thing but I do recommend a dual master cylinder. Don

Also, mine's a 53 and I guess the pumpkin was a 4.11. Anyway, it works. D.

Also on the 47, belive your trans to bellhousing pattern is the last of the old small type. You would need to swap to the next series version bell or use an adaptor to go with a modern trans.

The ring and pinion from Patrick's is for half-ton rears and won't work in your truck. I like the pumpkin swap from a late 60's early 70's 3/4-ton best for your situation, but they are not always easy to find. (Search this site for details on which ones fit.)

JiMerit is correct, that the '47 has the earlier bellhousing and transmission. To swap to a later trans you'll also need a later, through '53 bellhousing.

I don't recall when the 1-ton changed from huck to bendix brakes. You might look to update the brakes just a few years to have bendix type brakes. If you aren't pulling a trailer and keep the speed reasonable you would probably be okay.

Otherwise I've seen two approaches to putting disk brakes on a 1-ton truck. The hard way is to swap the complete IFS from a 3/4-ton or 1-ton Chevy pickup '72 - '87. The other hard way is to make your own caliper brackets and put rotors on your existing hubs.

If you update the brakes I'll want to know how you approach it and what you learn. I'm thinking about putting disks on a 1-ton and want to know all I can about how others have done it.

I've got a 3/4 ton with the 4 speed tranny and 4.56 gears. I can go 65 mph as a maximum cruise, but I'm spinning the engine at around 3200 rpm. I can hit 70 for short bursts, but it's still barely adequate to keep up with traffic.

Therefore, I have looked into Gear Vendors and found that they do sell an OD unit for the SM-420. You're looking at around 2 grand, but it could give you a true 8 speed transmission, with a supergranny gear, a granny gear, and a 0.78 overdrive in 4th over.

The other option is to adapt a rear end from a later truck. But for a Stovebolt that has limited rpm ability, more gears would be just what the doctor ordered.

By the way, the brakes are strong, but not being power brakes, you have to stand on them pretty hard in a situation, but they do respond. I've even towed with the stock brakes, and towing a car on a flat bed trailer, the brakes will do the job, but you have to plan ahead.

I've done that too.

The last time I swore I'd never do it again and that's when I bought the K3500. Unfortunately other drivers weren't always cooperating with my plan and nearly soiled my drawers.

I like brakes.

As an FYI to you bigger bolt owners - like 3/4 and 1 tonners, you can now get those 3.90 pinions from Jim Carters!!! Shop soon and get that discount before dec 15th. I saw the new item while perrusing the catalogue. I was lucky and found a gear set that I could just plug in.

Also, go get yourself the tallest tires you can find. That helps as well.

Once my 72 is did, I am adding a brownie to mine and I'll try to document what it took to do so.

Installing a 410 pumpkin from a 67 to 72 GM truck and using tires as tall as the originals will yield about 2460 RPM at 60 mph. It took me three years to find one of the pumpkins. Now I have a 457 sitting around that I picked up just in case I couldn't find a 410.

You know, I wouldn't hesitate to re-gear my rear end if I could also put some kind of posi or maybe a Detroit Locker in it too, so that it's not 1-wheel drive. Does anyone know if there is something made for our rear ends to get them 2WD?

As far as the tires, when I bought my truck, I had a set of what looked like really tall and skinny school bus tires. When I went to the tire store, I was told that I had a size that was no longer made and that split rims are extremely dangerous. So I bought a set of modern truck wheels and a brand new set of 235/75R-16 tires. The modern tires handle infinitely better, but they are a few inches shorter than my originals.

I know that hurt my top end, but it helps acceleration, and my stovebolt could use all the help it can get.

To get the 3.90 gears, you need a '63-'72 pumpkin, anyway. Might as well just get a 4.10 and save $500. The 3.90s are a waste of money for the minimal improvement, IMO. If they were 3.55 or 3.70 gears, it might be a bit different.

Looking through the new paper version of the Jim Carter catalog, I did see the 410 gear set but not the 390. Also, I couldn't find the bearing and shim kit. Maybe those parts are too common for them to carry.