Here are the ratios we're talking about:
Standard 3.14 2.01 1.32 1.00
Close 2.19 1.57 1.23 1.00
Std/OD 2.57 1.65 1.08 0.82
Close/OD 1.80 1.29 1.01 0.82
It's clear from these numbers that with close ratios, the overdrive is
not as useful for splitting gears. However, what's missing from this
discussion is rear end ratios. If you run an overdrive, you should
probably run a higher gear in the rearend. For example, a 4.55 in 4th
overdrive is 3.73, almost the same as a 3.70 in 4th with no overdrive.
Henry Frye wrote:
>Has someone looked at the math using the commonly available close ratio
>gearset with an OD? I know 3-OD is taller than 4th, so you would never use
>that accelerating up a straight. Where does 2-OD fall in relation to 3rd?
>Probably pretty darn close, again making it not something you would use for
>faster straight line acceleration.
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