The Stovebolt Site Forums The Shop Area Engine Shop Best drivetrain swap for a 53 chevy

Hi, I'm rebuilding a 53 1/2 ton 3100 series 5 window truck with my Dad. This is our first project so we are still learning. I want to have better drivability for highway than the stock torque tube 4:11 axle and 3 speed transmission. I was told that a good choice would be any 55-62 chevy truck with a 4 speed transmission. I heard that many of these have axles with 3:55 ratios. The only modifications would be to have a new driveshaft made. Is this correct? With my limited skill, I would prefer to stay away from any swap that is to complex. Is there a way to tell the gear ratio without counting the gears on the ring and pinion? I appreciate any tips you can provide. Thanks.

The standard gear ratio for the 55-62 3100 is 3.90 to one. The after market gear set for this rear axle is 3.33 to one. You can change the whole rear axle from a 55-59 by changing the spring pads or you can install the diff. in your axle housing and weld the axle pivot or install new spring pads. Easy swap.

I sent you a PM.

Dave

I'd go for a 261, wish I had know about them when I was in high school. Instead I rebuilt a 235 for my 1 ton (while in high school) at the time I wanted lots more HP, but looking back the 235 was a great decision and I learned a lot.

Doing something reasonably stock with easy to get parts and most of the answers in the service manual is a good idea for a first project. Save the unusual or far from stock engine swap for your second or third project.

For a transmission either the 3 or 4 speed and faster rear axle gears. Neither have Over Drive, and the advantage to the 4 speed is a nice slow first gear and a floor shifter.
Or I'd seriously think about a T5 5 speed OD possibly with stock gears. You'll need to go to an open driveline though.

Grigg

Thanks Lonnie, were they any 55-62 trucks with higher gears than the 3.90? I was told that some did have 3:55 or somewhere in the 3:30 range. Will the 4 speed from these years help with rpms at highway speeds? I have never replaced a set of gears so doing the entire swap would probably be easier for me. Are there any other 4 speed/axle combinations that would bolt right in?

Trucks with automatics had 3.38 gears ('55-'62) They are not very common. Aftermarket gear sets are available though.
The truck 4 speed (SM420) has a 1:1 final drive ratio, so no, it won't help you with highway speeds.

We drive our '50 if not every day, every week. It has a 261 that we warmed over a bit but that's a matter of personal preference. We installed the rearend out of a '78 full size Blazer and it was the correct width and still had the 6 lug axles so we could keep matching wheels. The rearend came with 3.08 gears so when we made the swap we installed a Saginaw car 4 speed. There are 4 versions of that 4 speed and we used the one that has 3 grooves on the input shaft which means it has a 3.5 to 1 first gear. (There is also a version with a 3.11 to 1 first gear and that would work well also.) We drove that combination for several years and it worked great. We even drag raced it on the 1/8 mile a bit. Later we changed the gears to a 4.11 posi unit and changed the trans to a T-5 which then got changed to a Tremec TKO3550. It is a great combination and we have put over 90,000 miles on the truck. All those transmission options bolted up to the original bell housing (we did have to change the clutch), all we had to do was have a correct length drive shaft built. The truck's name is Walter and there are pictures of him in the Gallery under Ron and Kim Plender.

Thanks, so the 78 rear end bolted right in without any modifications even with leaf springs? That seems like a better alternative than using a 55-62 axle since they usually came with 3:90 ratios.