The Stovebolt Site Forums The Shop Area Driveline more MPH, less RPMS

I am looking to get more MPH and with less RPM out of my 1937 1/2 ton. She has a 235 with all stock drive train and rear end. I would like to keep things as original looking as possible and not get my self into to much work. I know I may be asking for a lot but I am looking for some opinions/advice on the best way to go about this.

Thanks for the help.
Charlie

Charlie,
We all want what you are looking for.
Your choices are:
Bigger tires,
lower ratio rear axle,
over drive transmission
or a modern 5 speed from an S10.

The issue is when you change the axle to an open type the transmission must also be changed and vice versa.

Would changing to a 3.55:1 ring and pinon be a good option? How much work would that be?

Charlie

Changing to a 3.55 is a great option, the only problem is there are none that fit a 37 rear end.
You would need to use a Power Glide car rear end or a 1940-54 truck rear end with Patrick's 3.5 gear set.
Both options would require some adapting.
I could talk you through it if you go one of these ways.

I thought I saw on patricks website that the have a ring and pinon for 37-54 chevy 1/2tons? may be I was seeing things.

Charlie

yes, Patricks lists the 3.55 for 37-54, both cars and trucks

Bill

You will find if you call Patric's that his 3.55 will not fit any truck before 1940, with out changing the rear end. 1940 was the first Hypoid design gear set for 1/2 tons. 1937 was the first for cars.

I'm thinking it's no longer stock with the 235 now so I'd pull the diff and trans and go with a T-5 trans! Or if you could find an early 50s powerglide rear end (3:55 gears) that could work. Either way some work will be required.

You are correct, I miss spoke about it being stock. The 235 is not but the trans and rear end are. How does the T-5 end up looking in the cab as far as the location of the shifter coming through the floor? If I go the early 50's powerglide rear end route could I keep the original trans and torque tube set up?

As far as cash and labor, IMO, tires would be the easiest way out. (I will look to see if I can find the formula) The correct "differant" tire will gain M.P.H., lower R.P.M., and still give you decent pulling power! Just my thoughts.

The formula is: "Effective Ratio" = "Old Tire Diameter" divided by "New Tire Diameter" times "Original Ratio". Note: These are actual heights of the tire NOT what it says on the sidewall. Example: A guy has a set of 28.2 tires and changes to a set of 32.8 inch tires and has a 4.11 rear end ratio. 28.2 divided by 32.8 times 4.11 = 3.53 effective ratio. Hope this helps.

Thanks stranger! I will see what I can come up with.

Charlie

Or if you don't have a calculator, these work well: http://www.onlineconversion.com/bigger_tires.htm

A 32.8" tire is one BIG tire!

DG

I found this first link a hand one to bookmark for auto info in general and the second one (from the first link) is handy for selecting a range of tire and wheel combinations to compare side by side.

automotive converters
tire and wheel calc.

37FamilyBowTie,

Please let me know what you come up with! I have owned several vehicles and have used this solution many times. Many old trucks could pull a house over, but going down the highway, the motor sounded like a sewing machine run amuck! You may not get to a "perfect" effective ratio, but you should be able to achieve a
happy medium! Also be sure to figure out your correct M.P.H. as,
Example: 50 m.p.h. showing on speedometer may actually be 57 m.p.h. actual traveling speed! Make a mentle note to remember or change speedometer gear to correct. Still way cheaper and easier than changing rearend, transmission, etc. Good Luck!

There is a member here that modified a 37 truck to get a better ratio. I believe he used components from a later late 40s car. There were driveshaft modifications too. I just can't remember his site name.

I guess I have some more thinking to do on this. thanks for all the info and I will let you know what I come up with. My other thought would be to just get another truck and leave this one the way she is.....she has a ton of family history tied to her so I dont want to change things too much.

charlie

I don't know if the 37 torque tube has the same dimensions as the 47-54 where it bolts to the transmission. If it does then what we have done is use the 3/4T driveshaft that is a torque tube on the front half and open on the rear half. You can then use the 55-59 TF 3.90 rear for which you can get 3.38 (or 3.56) gears that are a lot easier to install in the open rear end. The spring perches need modified and a hanger bearing cross member installed but neither is hard to do.

What would be my options with trying to go with an over drive?

Charlie

For my two cents worth, go find a Truckstell overdrive made for dealer installation on 47-54 chev cars. it bolts onto a shortened torque tube. It should bolt right up to your tranny and mount to your tube. Truckstells give 28% overdrive,will change a 4.11 into a 2.96 or a 3.90 into 2.80. You'll still have your low ratios for "intown" and "parade" driving and a tall setup for the highway. They are a great unit if you can find one. Best Regards and happy motoring, KB aka telekenfun

Thank you for the tip. I'll look into that
Justreg