I have been digging in the forum archives for the correct speedo formula and found it, thanks to all who have provided this invaluable info.

What the younger guys/gals in this hobby don't realize is how much research in libraries, dealerships and auto shops it would take to learn this kind of info. I have had my 67 SS since 1976 and conducted this speedo research in depth back in the early 80's and NEVER found the answer. THANKS AGAIN!

Sorry for being so verbose ... I just had to say that!!

QUESTION?

I plugged my variables into the calculations for speedo gear ratios and found that I have to use my .7333 multiplier to get the correct ratio. If one does the math:

What I have currently for gears

Driven 36T ÷ drive 15T = 2.4 but I need 3.25 for my setup according to the chart. WHY THEN do you divide the multiplier .7333 to get the ratio ... that is instead of MULTIPLYING it by 2.4?? Since it is obviously reducing driven output by .7333

Why did I divide??? My speedo was close before I started with a new tranny I built with a 18t drive.... I did the math using the old #'s to make it work .. multiplying created weird ratios.

I don't understand the math here.

Always grateful for this forums generous giving of their knowledge.

Larrie