The Stovebolt Site Forums The Shop Area Driveline Help: which auto transmission.

I purchased a 1957 Chevy truck with the 235 engine and a TH 350 automatic transmission. I haven’ driven it a lot but it seems to lack guts at the higher RPM and the hills. I suspect it’s the gearing or the transmission and I suspect I have the original 4.11 rear end. According to Tom Langdon’s site the better mate is a 200 or 700 with OD and the 350 is near the bottom of his recommendation list.
The question is? Any body out there have any experience with the either of the transmissions and should I change the transmission or the rear end gears.
Because I have a 350 in there now I’m not sure if I would have to change the adaptor or the shifter if I go to a different transmission but am it sure.
The tires on it are 235/75R15. 28 “ high.
Thanks, Dave

You could have something as low as a 3.38 ratio in the rear end Dave. The TH350 and the 235 might not be such a bad marriage, but not what i'd think would be a natural. Find out what your rear end ratio is first. That ought to be your first concern. You do know the 235 is not a high rpm motor, right?

You can find out the ratio or close to it by jacking up the rear end and supporting the truck on jack stands. Then mark the driveshaft and the tire then rotate it and see how many turns.watch this.

You will see zero improvement in performance going from a stock manual 3 speed to a 3 speed TH350 automatic transmission. In fact you will likely see a loss of performance due to lack of precise shift points of the automatic transmission.
A 200R or 700R will not improve performance at higher RPM nor on the hills. The overdrive will be nice for driving faster than 50 MPH.
The bottom line is, you are expecting too much from a 235 with an automatic transmission (TH350, 200R, or a 700R).
If you do decide to switch to an automatic transmission with overdrive, resist the temptation to use a rear end with a ratio of less than your 4.11 to 1 which you currently have. Performance and fuel mileage will suffer.

Thanks all for the input, it’s all helpful. I do realize that the 235 is not a high RPM motor and 2000 rpm seem to be the sweet spot. I will confirm what the rear end gearing is. Thanks for the tip on how to do that.
I have a 51 with a 1956 engine and 4 on the floor but has a 3:55 rear end. It has with much better performance than the 57 with the automatic.

1956 car or truck 235 engine?
What is the feature/characteristics/benefits of the/a "sweet spot"?

1956 235 truck Engine Performance graph.