Someone told me the other day an equasion where you multiply the 2nd gear ratio by the diff ratio. What exactly is this working out and what answer should i be getting? i take it it must vary with tracks?

Thanks.

I would say for a final figure in that you would need a tyre measurement aswell (either height or circumference) which could then give you rpm or mph.

Hi Kev,
It sounds as if someone was explaining how they compare overall effect of different diff ratios when running in second or third gear with a Quaife or TranX gearbox.

For example a 3.7 in second is 3.78 x 2.07 = 7.825
and a 3.9 in third is 3.89 x 1.98 = 7.702

The formula is:

___ Engine RPM ___ = Wheel RPM
Diff ratio x gear ratio

or

Engine RPM x 60 x Wheel circumference (in inches) = MPH
Diff ratio x gear ratio x 12 x 5280


If you are really interested send me a PM with your address and I will send you a chart.