How to calibrate a mechanical speedometer
How to calibrate a mechanical speedometer.
The speedometer is from a Land Rover Defender, but it is a generic VDO part. The internal mechanism is similar to most other mechanical speedometers.
Notes:
-The drill has to be in reverse. I used a C-clamp to adjust the speed.
-There is a hole next to the posts that the hair spring winds thru. The hole is for a plastic pin to hold the spring in place.
-If the spring sits off center, you can gently bend the outer loop of the spring. Be careful it can easily be damaged.
-I meant +/-20% is the most you can adjust it. By setting 60mph at 1030 rpm (instead of 1000), I adjusted it 3% high.