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........

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Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp

Is this something that is deemed to be required?
Having 4wd with track rubber I would have thought that traction will be pretty darn impressive for acceleration purposes. In challenging weather conditions (and assuming you don't have ABS?) I would prefer to learn the grip levels by prodding the accelerator and seeing what sticks than prodding the brake and seeing it doesn't stick. (generally my approach for testing grip levels).

Oh and is your throttle drive by wire now? That is much better method of traction control IMHO. I did wonder how 4wd coudl run traction control, linking to GPs is very clever but it all sounds like a recipe for possible problems with many things attached that could limit power.

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JP
GT4DC Treasurer

Grey St185 RC
Silver BMW E46 M3
Multicolour yawn Honda VFR400
Silver Honda Civic Type-R

How does the traction control system know when a wheel is spinning ? Does it just look for a sudden increase in speed, or does it need an accurate speed or accelleration reference ?
If it's comparing wheels and looking for one wheel 'spinning up' then I doubt it will work well. especially with track spec LSD's which will pretty much lock all 4 wheels together.
I don't think GPS would be a viable option as it's a bit slow and unreliable, especially at low speeds which is when you most need it.
The sensible option would seem to be using an accellerometer and comparing carr acelleration against rate of change of wheel speed, and then cutting power if the wheels get too far ahead. Is this an option on any 'off the shelf' solutions ?

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If at first you don't suck seed, try drier grain.

I agree with Chris re GPS

From raw logs on cycling I can reach one of two conclusions :-
1) I a a cycling God with legs capable of producing the several hundred bhp required to accelerate to speeds in excess of 100mph almost instantaneously

2) short term readings at low speed aren't that reliable

I'll leave you to draw your own conclusions but 1) doesn't tally with my dyno day results

I did manage to record a speed of 150MPH in my diesel clio while passing through the hatfield tunnel

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If at first you don't suck seed, try drier grain.

The Racelogic TCS system simply compares the relative rotation of the wheels to sense slip. Clearly this works in a 2WD setup which compares the driven to the undriven wheel rotation. With 4WD all four wheels are driven UNLESS one of the front wheels starts to slip. Remember it's an open front diff on the Four I've had the Four in a lovely balanced four wheel drift through Silverstone's Club corner in the wet. Great fun overtaking Caterfields and similar then I was blitzed by a Ferrari 355 on full race wets to bring me back down to earth

Regarding the use of GPS this is now quite sophisticated on autonomous race lap timing systems e.g. AIM Solo, MoTeC, Racelogic etc. I can well imagine with the iPhone apps and similar then unprocessed flash readings may give wacky results

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Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp