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HELP HAS ANYONE HAVE INFO ON GETTING MORE SPEED FOR THE 3/4 TON PU 49 LATE MODEL

Old 49er,

Welcome to Stovebolters! If you are trying to keep it more like original you have a couple of things you can do. If the old 16" wheels have been replaced with 15" you can pick up a little speed by putting the correct wheels and tires back on. This makes it set higher and I guess it does't look as "cool" by today's standards.

Another improvement would be a rearend swap. You can stay "original" if you can find a '54 rearend. Your '49 has a 4:11 and the '54 has a 3:90 but still has the enclosed driveshaft.

Another option is new gears (Patrick's etc.) which is expensive and should be done by a pro.

Remember, the old AD's weren't exactly built for high speeds. Make sure your brakes are in very good working order and your doors won't "bump" open. I put seatbelts in my '52.

Good luck!

Jim

THANKS JIM TIRES ARE 16" IM JUST TRYING TO GET AROUND 65 MPH IM PUSHING AROUND 50 NOW WITH A 235 DO YOU FILL THE 3:90 REAR END WILL PUT ME IN THAT BALL PARK

You presently have a 4.57 or optionally a 5.14 rearend ratio in a 3/4 ton.

The kook has a good writeup on a swap that will get you a little more speed.

If you can presently do 50mph with a 4.57 (which sounds about right) you will be able to do 55mph with a 4.11 running the same engine revs or if you buy a 3.90 kit (I believe sold by Randy's Ring and Pinion) you will be able to do 58 mph.

Patrick's gears are for the 1/2 ton. Randy's Ring & Pinion no longer has the 3.90 gears. About the only way to go is with the pumpkin swap described by Kook.

Anyone out there have a 67-72 rear end I could put in my 1950 truck? I haven't found one locally yet.

If your truck still has the torque tube rear end, the swap is more difficult. This is cuz you've got to mount the newer R/E to the suspension, find/cut down a driveshaft and convert the tranny to use an open driveshaft. Lots of info here on the swap.

chip

Here are some possibilities.
1. Put an ad in the swap meet on this board.
2. Go to the 67-72 parts board . Put an ad there or search for Teeitup, he lives in Meredin (north of Topeka). He parts out trucks, I had him look for one for me. Took a few months, but I got one.
3. Contact Tom Myers, Miami, OK 918-542-3871. He might have some pumpkins.

What is a torque tube rear end? I assume the truck to be an all original 1950 3/4 ton.

MK-

Welcome to the Stovebolt. Good question.

If the truck is indeed an original '50 3/4 ton, the driveshaft is enclosed between the transmission to the rear end U joint within a steel tube/pipe known as a torque tube. Later models (after '55 I believe, but certainly by '57) had a single steel drive shaft. Others may correct the details here, but the '50 vintage truck had a unique driveshaft set up. It will be straightforward to upgrade to a steel shaft if you are swapping out the rear end.

Does this help?

I'll look again but I don't recall seeing anything but a ordinary drive shaft.

MK-

The torque tube may look a driveshaft to you, but it is a shaft within a tube. Look at the U joint ends to see if the shaft is enclosed. Alternatively, someone ha already made the swap and you have a standard driveshaft. That would be good news in this upgrade.

OK, I just looked it over. Please pardon my ignorance on these old trucks. I'm new to this vintage.

The shaft is in two pieces. In the middle, there is a mounting to the frame. I assume some sort of carrier bearing or something (leaking by the way). The front half of the drive shaft from the tranny to the bearing is enclosed because I see no u-joints. From the bearing to the differential, I see a regular drive shaft with u-joints.

Can you tell me what this is? Is this original?

The last time that I talked to Randy's Ring and Pinion, I was told that they still have a 4.10 gear set but not the 3.90 set. I don't know if it was good information or not. Anyway, these gears only fit into the more modern 67 to 72 assembly, not the 1950 assembly. The more modern assembly is a boltin.

All of the books I have (1951) state that the torque tube drive train is only on the 3100 series 1/2 ton trucks. I have a '51 3604 Chevy Pick up with a 4 speed and 4.57 ratio full floating rear axle. Other than a '57 235 engine and newer rims the truck is original. I installed a set of 7.50 16 bias ply tires on rims from a 95 chevy 3/4 ton truck. I can cruise at 65, and the 8 ply tires hold 60 psi, I keep 45 psi in the tires and it makes for a fair ride and easy steering.e

Well, where does that leave me for an upgrade in rear end gear ratio? Can I swap out with a 67-72 c20 pickup? Do I need to find new ring and pinions?

Based upon what I said in my previous post, do I have an torque tube or is this considered an open drive shaft?

Any help is appreciated.

Mike - From your description you have the stock 3/4 ton driveline. Front portion of the driveshaft is enclosed, rear portion is open. To upgrade your gears, you need the pumpkin (center section) from a 64-72 with a ten bolt full-floating differential with 4.10 gears. The swap is fairly easy, but it does take two people, due to the weight of the pumpkin and the location. Follow the instructions from Kook, and you'll be okay. The most difficult part is locating a differential.

Do you have a factory service manual? If not, you should get one from one of the vendors, cost is about $30. It will be the best tool that you can buy, has instructions on how to repair almost anything on these trucks.

Thank you. I do have a manual and it has been helpful. Do you know if there are other ratios produced such as a 3.90 where I could purchase the ring and pinion and have them put in? Do you think it'll make that much difference? If not, I would much rather get a used 4.11 since it will be easier.

Can anyone tell me how to identify the ratio of the rear end?

Yes,
"Jack up one tire if you have an open diff, or both tires if you have a working posi or locking differential. Rotate the tire one full revolution for posis and lockers and 2 full revolutions for open diffs. Carefully count the number of full
revolutions the driveshaft makes. This is your gear ratio. In other words, if the drive shaft turns 3 & 3/4 turns, you probably have a 3.73 gear ratio. Turning the tire for twice the number of full revolutions and dividing the drive shaft
revolutions by two will give you a more accurate
reading."
(quoted from West Coast Differentials)

I'm considering the possibility of swapping the original torque tube rear end in my '51 3100 for another torque tube rear end from a passanger car from the same era with better gearing. Does anybody have any suggestions of which years/models I should look for?

Michael,

I have a '53 3/4 ton- originally 4.57:1 rear end. I put in a "pumpkin" from a '72 Chevy 3/4 ton van with 4.10:1 gearing. It took about half an hour with a good helper. Make sure your donor pumpkin is the higher gear ratio by counting the revs. Mine was marked but I turned it anyway before installing just to make sure. Find a junk yard that does 60's-70's Chevy trucks. I paid $250 for mine- well worth it. I can easily do 65 mph with my '54 235 and stock 4-speed. Good luck.
Tyler

No portion of a stock 3/4 or 1-ton driveline is enclosed on a '47.2-'55.1 truck, at least on any I've ever seen.

$250??? I paid about $60 at the local pick-n-pull for my 4.10 open pumpkin.

Michael, there are a few ways to indentify the gear ratios. One way is described above. If you pull the rear diff cover, on the end of the pinion shaft you will see a series of numbers. The ones you car about will have a hyphen "-" between them which describe the number if pinion and ring gear teeth. These are what determine the ratio. For example, you might see "GM-7-32". This indicates 7 pinion teeth & 32 ring teeth for a ratio of 32/7 or 4.57. It's a good idea to count teeth on each just to be sure. I'm just in the process of finishing my swap-I'm painting the diff cover and looking forward to seeing the difference in the high end speed. The swap is very easy if you have a rolling floor jack to carry the new gears-I didn't even have to jack up the truck. Make sure that your pinion seal is in good shape. For $13.00, now's the time to replace it.

I had a '47.2 3/4-ton a year ago. It had an enclosed driveline the first few feet back from the transmsission, and was open from the end of the tube to the differential.

I've just acquired a '52/'53 1-ton and need to look under it soon.

I did the 457 to 411 swap on the 51 chevy 3/4 ton
I was told that 67 to 72 suburban with automatic and big block 400 some came with a 373 rear end I found one but guy would not part with it they are very hard to find. good luck

This is only gor 3/4 tons though right? is it possible to take the tube/driveshaft off of a 3/4 ton, shorten it and put it in a half ton? I also aquired a 52 3/4 ton this weekend and have yet to check what it has. Thanks.

Oldsub, I know my '52 and '54 1-tons have exposed u-joints at the back of the transmission.