As part of the track toy project I've been looking at using the ABS sensors as wheel speed sensors. The standard speed signal in the ST205 is generated by a sensor in the gearbox. The disadvantage of this is that you can't tell if there is any wheel slip. The OEM Toyota sensors are twin wire inductive magnetic sensors rather than three wire Hall sensors. Hall sensors are more commonly used in motorsport as the square wave signal can be read directly by most aftermarket ECU's. Unfortunately the diameter of the Hall sensors is too big to fit in the ABS mounting holes and I didn't fancy trying to machine the holes in the hubs.
Recovering the old sensors from the hubs in one piece proved to be a bit of a mission to say the least despite the copious application of Plus Gas. The front hub sensors in particular are not very robust as the mounts are plastic and the metal sensor body tends to 'freeze' with corrosion in the hub
By the way thanks to everyone who has helped by donating their old hubs and/or sensors. I'm still short of good condition front hub sensors so if anyone has some lurking in a corner please let me know.
I plan on using a MoTeC dual magnetic converter (DMC) to convert the OEM Toyota ABS sensor sine wave output to a switched or square wave Hall type signal. This will enable me to run traction/launch control. With the OEM Toyota viscous centre diff fixed at a nominal 50:50 torque split I can't do anything more sophisticated still, it should prove quite useful in the wet to supplement cockpit selectable maps.
Non of this is particularly revolutionary as Racelogic have offered a traction control solution for some time which uses the standard ABS sensors. According to my wiring guru the MoTeC ECU can also be configured to convert the ABS pulses to an equivalent wheel rotation value and with the tyre rolling circumference plugged in then it's possible to produce a speed value. This seems to give reasonably reliable readings down to speeds as low as 5mph. Traction control can be implemented by the MoTeC cutting spark but being four-wheel drive I may have to supplement the ABS wheel speed inputs with a GPS speed as a reference if there is not enough difference in the wheel speeds to trigger the TC. We shall see........