Ring and Pinion Speed Calculator
 

Ive been searching for it and can't seem to find it...


Someone a while ago posted a ring and pinion excel calculator that would let you input the information and it would tell you the max speed in gear @ redline.


If not, I have a 94' with stock open and a dead tach and need to use my speedo as a tach temporarily. So speed to rpm with my open (I think it was 4.10) @ redline would be much appreciated, excel even better however.

Here, I just wrote one in Excel that's Miata-specific. Enter your R&P ratio and tire diameter (in inches) the green boxes. Get the tire diameter from the manufacturer's datasheet. It's pre-loaded with the standard transmission gear ratios for a 5-speed, and the MPH comes out for each gear in 500 RPM increments in the yellow box.

You are a god good sir.
:)

Or you can put in the wheel size here Tire size calculator

This is the best one yet, from our friends at FM.

Flyin' Miata : Technical info : Gearing calculator

I re-did the sheet in 250 RPM increments, in case you need some extra resolution.

Also, be aware that the values which the tire calculator Artie posted are "nominal" values. Actual diameter will vary slightly between different tires of the same stated size, not just between brands, but even for different tire models from the same brand. To get the exact OD for your particular tires, you can either measure them with a cloth tape (of the sort used by tailors), or download the specs from the manufacturer's website.