RESTORING HISTORY ONE CAR AT A TIME

SPEEDOMETER DRIVING GEAR INFORMATION

To assist dealers and stockmen in identifying the various speedometer gears used in Model “A” and “AA” cars and trucks, we are listing the following information:

A-17285 Speedometer driving gear (Service). Used on Model “A” chassis with axle gears of 9 tooth pinion and 34 tooth driving gear, 10 tooth pinion and 37 tooth driving gear, 9 tooth pinion and 37 tooth driving gear and runs with A-17271-B or A-17271-E driven gears. Has 7 teeth. Outside diameter is 1. 728/1.729.

A-17271-B Speedometer driven gear (Service). Used on Model “A” chassis with axle gears of 9 tooth pinion and 34 tooth driving gear, 10 tooth pinion and 37 tooth driving gear. Runs with A-17285 driving gear. Has 18 teeth. Outside diameter is 1.0215/1.0225.

A-17271-E Speedometer driven gear (Service). Used on Model “A” chassis with special service axle gears A-4209-C having 9 tooth pinion and 37 tooth driving gear. Runs with A-17285 driving gear. Has 20 teeth. Outside diameter is 1.122/1.125.

AA-17271-BR Speedometer driven gear (Service). Stamped 5.17 on the face.

AA-17285-BR Speedometer driving gear (Service). Stamped 5.17 on the face. Used on AA chassis (approximately the first 5000) with worm axles of 5.17 to 1 ratio (high speed). The driven gear for this set is the type used with a drive cap.

AA-17271-BR has 15 teeth. Outside diameter is .856/.857. AA-17285-BR has 5 teeth. Outside diameter is 1.851/1.854.

Note: There are no· “low speed” speedometer gears available of this “cap” type. If the axle gears are changed from high to low speed and speedometer gears are desired to match, it is necessary to change the torque tube and put in AA-17271-E and AA-17285-E gears which require the “bushing” mounting used at present. AA-17271-D Speedometer driven gear (Service) Stamped 5.11 or 5.17 on the face.

AA-17285-D Speedometer driving gear (Service) Stamped 5.11 or 5.17 on face. Used on AA chassis with worm or bevel axle “high speed” of 5.17 to 1 ratio for worm and 5.11 ratio for bevel axles.

AA-17271-D has 19 teeth. Outside diameter of gear is 1.036/1.039. AA-17285-D has 6 teeth. Outside diameter of gear is 1. 713/1.715 The driven gear in this set uses the bushing mounting and has a short shaft integral with the gear.

AA-17271-E Speedometer driven gear (Service). Stamped 7.17 or 7.25 on face. AA-17285-E Speedometer driving gear (Service). Used on AA chassis with worm or bevel axles “low speed” of 7 .25 to 1 ratio for worm and 7 .17 to 1 ratio for bevel axles.

AA-17271-E has 18 teeth and is same type as AA-17271-D. Outside diameter of gear is 1.005/1.008. AA-17285-E has 4 teeth. Outside diameter is 1.744/1.746.

AA-17 2 77 -BR Speedometer drive cap and plug assembly (Service). New number issued to cover this part which was used on approximately the first 5000 trucks built only. It is used with AA-17271- BR driven gear 5.17 to 1 ratio.

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