The Stovebolt Site Forums The Shop Area Driveline Drive train upgrade

I have a 1950 Chevy 3100 with a 235 followed by a manual 4-speed tranny that has a torque tube driveshaft going out back to a set of 4.11's. As you can imagine, 50-55 is about the limit on the highway without blowing something to smithereens. Can anyone tell me if I can change the torque tube driveshaft and the rear end to one from say a 55-57 Chevy truck or car? I'd like to have the open driveshaft and a rear diff that has something in the neighborhood of 3.25 gears to get a better cruising speed on the highway. I go to some car shows with the truck, but can't go far and don't want to put it on a trailer! Any advice will be greatly appreciated as I would like to keep it looking stock, just something with lower rpm's at 65-75.

I purchased a 53 3100 that came with a 2nd generation 235 installed with a T5 5 speed and a 12 bolt rearend. I'm not sure what the gear ratio is at the rear, but I cruised at 65-70 on the freeway. Looking at the installation it looks to be pretty straight forward.

Good luck with with your truck.

jim

Jim

Welcome to Stovebolt! When you have a chance you can do a search on this forum and there are many options that you can read about.

Here is a link to a tech tip that I wrote a few months ago that will keep your existing driveline and change the gears to 3:55. This will allow you to cruise the highways all day long.

3:55 Tech Tip

This option will cost about $850 with the rebuild kit and you will have a better-than-new setup ready to go.

This is the setup that I have in my '51 with the stock SM420 transmission.

I have a 12 bolt 3.08 to 1 rearend with a 3 speed transmission (1 to 1 3rd gear ratio) and can do 70 mph all day long. The only drawback is it is wimpy in first gear. No free lunch, as they say. I would rather have a 3.73 to 1 rearend with a T-5. Now that is free lunch.
Carl

Thanks for the info. Do you happen to know what the 12 bolt came out of?

Thanks for the info. Do you happen to know what the 12 bolt came out of?

I appreciate all the great advice, but never really got an answer to my original question. Will the driveshaft & rear end from a 54-57 car or truck be a direct bolt in to the 50?

The simple answer is yes...and no. It is the right width, but the spring perches aren't the same. You'll have to relocate the '55- '57 spring perches. Other issues of course are pinion angle, driveshaft length, etc. A rear from a '55-'57 powerglide car
has a 3:55 rear as stock. That's a good choice with a T5.

But, really consider what SWEET has Tech Tiped for us. It's a good way to go.

"1950 Chevy 3100 with a 235 followed by a manual 4-speed tranny that has a torque tube driveshaft going out back to a set of 4.11's"

"I appreciate all the great advice, but never really got an answer to my original question."

Questions:

1. "Can anyone tell me if I can change the torque tube driveshaft and the rear end to one from say a 55-57 Chevy truck or car? "

2. "Will the driveshaft & rear end from a 54-57 car or truck be a direct bolt in to the 50?"

Short answers:

1.Yes, you can change anything if you have the time, $$$, and expertise.

2. No - not a direct bolt in (except perhaps from a 1954 Chevrolet/GMC 1/2 ton truck)?

There most likely are no other simple answer? But, it would nice to be wrong.

Many people here have done many conversions, most of which most likely require non-simple descriptions?

Not sure, as it was on the truck when purchased. My guess is late 67-72. The 3.08 to 1 gears are not good on the clutch in 1st gear with a heavy load or on a steep hill. It is however great for doing 75 on the highway, except for the stopping part. Bottom line is, I would not choose it for one of these trucks.
Carl

A 55 first edition rear should bolt in place with the springs, it is not a torque tube rear end.

That 3.08 rear probably came in a 2nd series gmc.Larry

What years? Were they 12 bolts with the hard to describe shape (not even close to round)?
Carl