Hey y'all. I been surfin thru my new book, the '53 Truck Chassis and Body Parts and Accessories catalog i just got off E-Bay. Gotta love getting good stuff in the mail. Anywho, I see 2 different Gear and Pinion sets listed for my rear end. It's the 3/4 ton with a 4-speed syncro tranny and 215/6. 1st is major granny low, and she really sounds wound up when the speedo shows 55mph. I usually just skip 1st, and start out in 2nd.
Is there a stamping on the rear axle housing with the gear ratio, or am I left with a mystery as the truck's ID tag is long gone. It's either 4.86 to 1, or 5.83 to 1. It would be nice to get to 55 without having her wound up so much, but I don't want to give up the stock 3/4 ton axle even tho I'd have to drop the whole mess to rebuild it or change gears. Please have patience with me as I'm dumber than a stump with all this gear ratio stuff.
Several different ways you can determine your axle ration without the tag. You can rotate the pinion by hand and count how many turns it takes to make one full revolution of the tires, or pop the cover and count pinion and ring gear teeth. I would think turning the pinion would be easiest for you, especially since you have 2 possible ratios to choose from.
A numerically lower (yet higher ratio) gearset will get you lower RPM's cruising at highway speeds.
The rear axle ratio is stamped on the 2nd line of the Rating Plate. 1953/54 F250, some 1955 F250's: Timken model A150 rear axle. Available ratios: 4.86-1 & 5.83-1. That's it, no other ratio was available.
Some 1955 F250's and all 1956 F250's used Dana (Spicer) 60's. If you want a 'high speed' rear axle, look for a 1957/72 F250 Dana 60: Available ratios: 3.54 (1966/72) 3.73 / 4.10 / 4.56.
The 1948/55 individual year parts catalogs are not very accurate. Ford made many part number changes in 1956, including changing some of the basic part numbers.
The 1948/56 Ford Truck Parts Catalog (final printing 1964) is available on a CD from hipoparts.com for about 20 bucks...or you can buy Carpenter's reprinted paper version for 200 bucks.
Peeps are usually unaware today that the highway speed limits "back then" were 35/40 MPH for trucks, 40/50 MPH for cars.
Since peeps usually didn't drive any faster than the speed limit (poor road conditions, unmarked lanes, no interstate hwy's, were other factors), there was no reason to have "high speed" rear axle ratios.