Re: Is overdrive really necessary?

Posted by Owen_Dyneto On 2014/11/5 11:25:16

Rear axle ratio also a factor. Typically OD-equipped cars came with a slightly numerically higher rear axle ratio that those without; thus adding OD to a car that did not already have it will give lower rpm cruising than factory-equipped and lesser hill-climbing capability if the ring and pinion were not also changed at the time of conversion to OD.

For example, 1954 Clippers with manual transmission:

Standard rear axle without OD: 3.9/1
Standard rear axle with OD: 4.1/1