Speedo reading 20Km/hr less than actual

[frog]

After changing my dials to nice white Lockwood ones - everything seemed OK except that when starting up, the speedo wouldn't move until I was travelling at about 20Km/hr - then would always read 20Km/hr out (checking with my satnav). I've checked that the speedo cable is plugged in and after pulling it out and replacing it a few times, nothing changed. Does anyone have any ideas - I'm sure if I leave it like this, I'll get a whole host of speeding tickets..

[Monty]

Make sure the dial is lying flat and that it`s not catching the base of the needle. There not a perfect fit and cause the locating holes don`t line up they end up bowing and touching the needle.

ps u have removed the old dials?

[frog]

Yes, the needle is well clear of the dial and seems to move freely when spinning the connection to the speedo cable. And I did remove the old dials first!

Anyhow, I doubt that it catching the dial is likely as it reads a constant 20Km/hr less than it should at all speeds - it is rather puzzling.

I hope I don't have to take the thing apart again!

[Paul.P]

Frog, you didn't remove the needle when changing the dials , did you ?. Also, did you check the speedo was pushed all the way home ?, can't say ive had any problems after the dial change

[frog]

No - didn't remove the needle at all - and I've pulled out the speedo cable and plugged it in a few times. Just seems wierd. All I really need to do though is move the needle up 20Km/h and I'll be fine. Could I have shifted the needle while installing the dial - and if so, could I just push it back?

[frog]

Looks like (somehow) I shifted the needle, so I puuled it off the spindle and reset it. My neighbors must have wondered what I was up to as I was going up and down the road at differing speeds each time trying to calibrate the dial with the GPS. After 3 attempts I got it reasonably close (erring in the cautios - slower side by 1-2Km/h)