There is no problem running speedos with either the IB5 or MTX Focus gearbox. The calibration is in fact in the PCM which converts the Vehicle Speed Sensor (VSS) signal to a serial signal on the OBD data highway. It also outputs a 'calibrated' pulse for legacy items such as cruise control and volume control on the radio.

The VSS sensor 'looks' at a plastic/metal wheel on the diff (which replaces the speedo worm gear in earlier cable speedo boxes) which has 26 teeth. so 26 pulses per driveshaft revolution.

The only mismatch is with an ST170 PCM/Gearbox. The outputs from the PCM are still the same, but the pulse rate from the gearbox is much higher. This is because the MT285 was never designed to drive a mechanical speedo. The VSS just looks at the crownwheel. So it outputs 89 pulses per rev of the driveshaft to the PCM.

So to use any other box with a ST170 PCM, or, to use a ST170 gearbox with an ECC-V Focus PCM (as I do) you either have to pay Ford to correct the PCM calibration or fit a frequency modifier. Ford can do the PCM calibration to correct for different wheel/tyre options; I don't know if they can do the major change needed for a gearbox swap.

I use a frequency modifier marketed for bikes, but also used by kitcar fraternity. Its called a Speedo Healer. It just goes between the VSS and the PCM and programmed with a pushbutton and a few switches. Unfortunately the Ford VSS is non-standard (according to the Speedo Healer manufacturer) so a couple of resistors are needed as well.

OK, its a self fit, but the unit is cheaper than even getting Ford to look at your car. Its also useful for minor recalibration for swapping wheels/tyres.

It's all written up as a How To on www.ffoc.co.uk.

Martin