[Johnno]

Hi Johnno,

Some styles of tachs use reflective tape to get a signal. Installing a small piece/strip on a tire sidewall or tread will tell you wheel RPM at a given voltage. Hold the car in your hand and power it up. Use the tach and multiply the number by your gear ratio and you're all set to start taking/recording motor RPM readings. Keep your voltage the same from test to test.

7000 RPM at the wheel is 21,000 at the motor with a 3:1 gear ratio. Time to get the calculator out.

No need to take a car apart to test final motor RPM.

Cheers,
Ken

Hi Ken, 

I've got on those digital hand units the only issue I have with that is the reflective tape likes to get spun off the wheel so not too enthused with that tach

Thanks
Johnno