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Speedo Reading Low
Robbie 2B - 28/6/12 at 05:00 PM

Finally got the car taxed & tested and back on the road with the Duratec HE just about fettled. One of the problems still to overcome is that the speedo is indicating a little on the low side.

As I have used the Mondeo instrument cluster the speedo requires a signal from a vehicle speed sensor (VSS). I have used a sensor from a Ford Ka and fitted this to the Type 9 gearbox using an adapter from Europa Spares. The signal from the sensor goes via the ECU to the speedo. The system works fine but an indicated 15 mph is way over 30 mph.

Searching the forum there was a discussion in 2008 on how to electronically alter the speed sensor's output but nothing on if different VSS sensors have different outputs. The Ford Ka being the rotating magnet type.

Can any guidance be given on

i/ Do different mechanically driven VSS give different signal outputs?
ii/ Are ready built 'sequencers' available and if they are where from?

Any help gratefully received.

Best regards

Robbie


jollygreengiant - 28/6/12 at 05:07 PM

The speedo drive is not a standard thing and can have different drive gear ratios to reflect the nature of the final drive AND wheel/tyre combinations. You might find it necessary to find a pulse generator with fewer teeth on the driven gear to increase the speedo reading.


edit bit.

The Ka unit I think was designed to be used AFTER the diff and the T9 takes the speedo drive from BEFORE the diff, so this is probably why you have an error. In an Ideal world may be you should have tried to get the gearbox from a Granada which came with electronic speedo as standard.

You might end up having to use something like a Speedo Healer to get this right.

[Edited on 28/6/12 by jollygreengiant]


austin man - 28/6/12 at 08:02 PM

have you lookes at the mondeo speedo drive these are electronic and if I recall look like they would fit into the type nine


Robbie 2B - 29/6/12 at 08:07 PM

Many thanks for the replies

The Granada VSS could be the way forward - however there is a lack of these cars in Bridges the local breakers!

The Speedo Healer may be the best, if expensive, option - it looks a good bit of kit.

The final drive on a Ka has a ratio of 3.6 so at an indicated 15 mph I would have been doing about 50!!

The Mondeo sensor gets triggered by a castellated rotating disc fitted after the differential, the Type 9 has a gear drive taken from the output shaft.

Thanks again for the interest

Robbie