Speedometer drive and digital instruments

[DavidL]

My speedo (Rover 213 dash) reads very much on the high side. Short of dismantling the final drive, I have no idea of what ratio it is, neither do I know what speedo drive ratios are fitted, and on top of that, I don't know whether a the drive ratio required for the Rover 213 speedo is different to the one required for the Metro speedo.

On top of that, I'm thinking about fitting a digital dash. What do they use to determine the car's speed, is it a speedo cable or some form of electrical/electronic transmitter?

[Hans Efde]

I had the same problem. I rectified it by fitting an other speedo drive pinion. There is a website with an overview of the speedo drives available. These are color coded. If you know which one you have in your car and you know the precentage it exaggerates, you can calculate that back to an other pinion. I forgot which website it was, but will search my notes and calculations. I recall it's on this forum somewhere s well. Anyway my 213 dash is now spot on with a 3.1 diff.
From under the car it's easiest to get the drive wheel out.

[Hans Efde]

Found it:
viewtopic.php?f=5&t=488&p=1992&hilit=drive+speedo#p1992

[DavidL]

Found it:
viewtopic.php?f=5&t=488&p=1992&hilit=drive+speedo#p1992

Thanks Hans! That looks very useful, I'll study it later when I've done my allotted carpentry chores for the day...

[Rich]

On top of that, I'm thinking about fitting a digital dash. What do they use to determine the car's speed, is it a speedo cable or some form of electrical/electronic transmitter?

I believe one or two may take the impulse from a cable adaptor but most pick up from a rotating component such as a driveshaft or a hub. Mine (Koso) reads the back of the studs in the rear hub. I then enter the distance covered in one complete rotation of the wheel into the unit and hey presto, dead on accuracy.

[DavidL]

On top of that, I'm thinking about fitting a digital dash. What do they use to determine the car's speed, is it a speedo cable or some form of electrical/electronic transmitter?

I believe one or two may take the impulse from a cable adaptor but most pick up from a rotating component such as a driveshaft or a hub. Mine (Koso) reads the back of the studs in the rear hub. I then enter the distance covered in one complete rotation of the wheel into the unit and hey presto, dead on accuracy.

Cheers Rich.

On a different note, are you anywhere near Bideford or Okehampton? I am going to a weekend of alcohol and motorbikes near Bideford in June, hopefully in the Midas...

[Rich]

Hi David,

In relation to Fife I'm very close to both! Okey is probably 45 miles from here and Bideford a bit further. If you look at a map of the area I'm in the bottom right corner near Seaton and close to the borders with Somerset and Dorset.

[DavidL]

Miles away then! Well, at least we won't be disturbing you with the noise.