Packard Forum Index » Pre-War (1899-1942)

Peter Packard,
THAT is exactly the information I was looking for! Thank you. Chris.

If you go to page 127 of the Data Book, it shows the RPM Per Mile (ie. 60 MPH) for all of the 1938 vehicles with standard ratios. it does not give the RPM Per Mile for the Econodrive as it does on page 48.

You would do well to install an overdrive unit. That would reduce engine speed at road speeds by about 30% with the stock axle ratio. With the correct factory axle ratio for the overdrive,it would reduce engine speed at road speeds by about 20%. My'37 120 has a 4.09 axle with 7.00 X 16 tires. Engine RPM at 60 MPH is 2880 RPM, according to the book. An overdrive unit with the present axle ratio would make my car a real road car, with engine RPM at about 2000 RPM at 60 MPH, while retaining the car's excellent driveability at low speeds in high gear.

The '39 water pumps have ball bearings and a mechanical seal, I think, and the drive end bearing in the generator is probably a ball bearing.
The un-shrouded, fixed pitch fan would probably consume 5 horsepower at those speeds, besides roaring like a hurricane. A pressurized cooling system would be a significant advantage at such speeds. My '37 120 has an atmospheric cooling system and plain bushings in the rag seal water pump. A custom modern radiator that fit farther forward in the shell and a modern type water pump with a shrouded clutch-driven fan would be much better. $$$$$$$$$$$

Here is a quick calculator
wallaceracing.com/calc-gear-tire-rpm-mph.php

Quote:

That’s because overdrive wasn’t available until 1939 with the one year only R6.