A-Speed

Resources

Practical guides for Model A Ford owners—setup, touring, and getting the most from A-Speed on the road.

How to Determine Your Model A Ford Rear-End Ratio

Identify your Model A rear-end ratio with a simple crank pulley rolling test—no differential teardown required.

Learn why vintage speedometers drift and how to test yours against GPS for honest touring speeds.

Understand the math behind MPH, tire size, and rear-end ratio—and see example RPM figures for real Model A setups.

Learn how overdrive affects RPM, cruising speed, and drivability—and how common Mitchell, Borg-Warner, RTS, and T5 conversions fit touring builds.

Measure tire diameter the right way—direct and rolling methods, wear considerations, and why accurate sizing matters for A-Speed RPM on tour.