Speedometer test

M

mleder

Senior Member
If you wanted to see if a speedometer of unknown condition works , and you wanted to drive it with a cordless drill motor what direction should the cable (motor) spin?. I realize you're not testing accuracy just seeing if it may have promise of being good.
 
mleder said:
If you wanted to see if a speedometer of unknown condition works , and you wanted to drive it with a cordless drill motor what direction should the cable (motor) spin?. I realize you're not testing accuracy just seeing if it may have promise of being good.
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reverse slow speed will work
 
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Work it out: viewed from the front, the engine turns clockwise. in forward gears the output of the transmission to the driveshaft is also clockwise. The speedo drive gear is a direct drive so it turns counterclockwise, and this CCW rotation is sent up the cable. So input to the speedo is CCW, or "reverse" as Gary WA points out.
 
mleder said:
If you wanted to see if a speedometer of unknown condition works , and you wanted to drive it with a cordless drill motor what direction should the cable (motor) spin?. I realize you're not testing accuracy just seeing if it may have promise of being good.
Click to expand...

You should under no circumstance use a drill to "test" your speedometer. This is and has always been very bad advice. A drill is high torque and if your speedometer binds internally you will irreparably damage internal components as everything is gear to gear driven.

The only test would be to turn the speedometer magnet shaft by hand, it should spin smoothly and fairly easily, if it does not, then you know the speedo needs to be serviced by a competent gauge shop. Drills kill speedometers
 
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