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need specs

Guest bkc

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what is the gear ratio of the rear end in a 47-48 roadmaster?

also how does it compare to the super of the same year?

i want more top end from the super and i have the roadie rear end sitting around.

can i gain enough advantage tobe worth the swap?

would a later model year work better? Hard info to get hold of.


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bkc, do you have a shop manual? Your questions will almost all be answered in there.

But for now, crawl underneath the car and clean off the bottom of the differential[rearend]. You will find a number stamped there. Probably a 4 with a - underneath it and a 1 or 4 beneath the line. Indicating a ratio of 4.1 or 4.4 to one. The entire "pumpkin" from 1940 through 1955 will interchange. A lot of work, but worth the time. I just did this with my '50 Special. By 1955, ratios of 3.36/1 , maybe faster, were available. I used a 3.36/1 from a '55 for mine. Dropped the crusing 3rd gear rpm about 650 rpm. Fantastic!


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