Datsun Roadster Speedomoter Pinion 16 Tooth NISSAN 5 speed Transmission speedometer pinion 16 tooth gear. Each tooth on a speedometer pinion gear represents 5 miles per hour. If the speedometer is running too high you need to get a gear with more teeth to slow it down. If the speedometer is running too slow you need to get a gear with less teeth to speed it up.