Typical rear axle ratios for various '57 Plymouth drivetrains

From: Daven Anderson
Email: l96lfury@springmail.com
Date: October 04, 2001


A V8 Torqueflite was typically a 2:93 to 3:31 ratio rear axle, a V8 Powerflite was usually a 3:54 ratio,and your 6 cyl. manual car was usually a 3:73 ratio rear axle. Using the stock 3-speed and rear axle gears with your V8 conversion will result in the car being shorter-geared overall than the factory V8 cars. If you intend to drive mostly in the city you might actually prefer the shorter ratio,but if you drive on the highway a lot you should change to taller (numerically lower) rear axle gears. The 6 cyl. transmission should work fairly well behind a stock-type 301-318. I used one in a '61 Belvedere 318 because in '60-61 the 318's 3-speed has a 2.12 first gear,the 2.55 first gear of the 6 cyl. trans. made the car a little livelier accelerating from rest and required a lot less clutch slip to get going. (the car had used two clutches in 80,000 miles,no thanks to that very high first gear!)