blt@cbscc.UUCP (Brian L. Tymchak) (01/11/85)
before moving into a real job, I know that Chevrolet speedometer gears are differentiated by the number of teeth on the gear; I imagine this is true in most other makes of vehicles. A variation of one tooth on this gear will result in a variance of the speedometer anywhere from ~3 to ~4.5 mph. The range is dependent upon the other tolerances in the system. Putting finer teeth on the gear to cut this range down leads to much quicker failure rates of the gear since this gear actually takes quite a beating. Hence, 2.8% variation, or a couple mph isn't really all that bad. If someone finds or knows of a supplier that handles precision plastic gears, spread the word.