West Coast Classic Cougar Speedometer Gear Calculator

Rear End Axle Ratio (ie 3.25, 4.11)

Rear Tire Height (Tire Diameter in Inches)

Drive Gear Teeth *
Factory Reducer Installed^• ?
None
Reducer for C6 w/ 3.91, 4.11 or 4.30 Rear End
Reducer for 4 Speed Manual w/ 3.91, 4.11 or 4.30 Rear End

^• Vehicle that were factory equipped with the
3.91, 4.11 or 4.30 rear axles came with Reducers

* Common Drive Gear Teeth:

C4, C6, or FMX: 8 Teeth (Some 429 Police Intercepters came with 9 Teeth)
3 Spd or 4 Spd Toploader: 7 Teeth (unless listed in this chart: View Chart)

1967 - 1973 Mercury Cougar (and Ford Mustang) Speedometer Gear Calculator

1967 - 1973 Mercury Cougar
(and Ford Mustang)
Speedometer Gear Calculator