SPEEDOMETER
An E.E.C. decree of 25 June 1976, regulates the speed displayed by the speedmeter in relation to the actual speed travelled.
This decree stipulates:
- The speed indicated by a speedometer must never be lower than the actual vehicle speed.
- Between the speed displayed «SD» and the speed travelled «ST», there must always be the following relationship:
ST < SD < 1.10 ST + 4 Kph
Example: For an actual speed of 100 Kph the speed displayed by the speedometer may be between 100 and 114 Kph.
The speed indicated by the speedometer may be influenced by:
- The speedometer.
- The tyres fitted to the vehicle.
- The final drive ratio.
- The speedometer drive ratio.
Any of these components can be checked without removing them from the vehicle (see information note N° 78-85 TT of 19 October 1978).
NOTE: Before replacing the speedometer, check the conformity of the following points:
- The tyres fitted to the vehicle.
- The gearbox final drive ratio.
- The speedometer drive ratio.
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