Speedo in reverse

[Ex_Audi_Owner]

Hi guys

Just a quick question. Should the speedo register speed while reversing? I only ask because i've never seen it before on any car i have owned previously.

Thanks.

 

[vile]

Good question iv nether looked I will have a look tonight

 

[jayok]

Yes, it does and it has on a number of previous cars I've owned too - Honda/BMW/Ford.

The speedomoter works electornically by measure the rate of pulses coming from a sensor on the output shaft of the gear box. The higher the rate of pulses the higher the speed. As such, in either forward or reverse, both speed and distance will be recorded.

In the non-electronic old days, a mechanical cable went from the gearbox to the speedometer and it works on the rate of change of a magnetic field to drive the speed do. As the fields were aligned for, going in reverse would actually drag the needle counter-clockwise. So to prevent this manufactuers used to have a little stopper to support the needle and prevent this from happening.

But this didn't stop the odometer going in reverse - cue Ferris Bullers Day off

 

[Ex_Audi_Owner]

Yes, it does and it has on a number of previous cars I've owned too - Honda/BMW/Ford.

The speedomoter works electornically by measure the rate of pulses coming from a sensor on the output shaft of the gear box. The higher the rate of pulses the higher the speed. As such, in either forward or reverse, both speed and distance will be recorded.

In the non-electronic old days, a mechanical cable went from the gearbox to the speedometer and it works on the rate of change of a magnetic field to drive the speed do. As the fields were aligned for, going in reverse would actually drag the needle counter-clockwise. So to prevent this manufactuers used to have a little stopper to support the needle and prevent this from happening.

But this didn't stop the odometer going in reverse - cue Ferris Bullers Day off

Excellent reply! I'm ***uming then that the mileage continues to increase with each bit of reversing I do? If that's the case it makes the total mileage on the car even better lol.

 

[jayok]

I'm ***uming then that the mileage continues to increase with each bit of reversing I do?

Yep - although if 0.1% of the mileage was in reverse you'd be doing well