Supra wheel speed sensor question

[Nick]

Hey guys, Currently wiring up my A70 Toyota Supra, with a wire in G4+ xtream

Ive been doing a bit of research about the wheel speed sensors. With this car its a 3channel system so one for each front and a single sensor for the rear which is driven from the R154 gearbox

Im looking to set it up for launch control and traction control

The car runs ABS and will continue to, So i can just tap into the abs ecu and take a DI for the driven and non driven speeds?

In my research alot of people are running into issues with the frequency maxing out at 500hz and causing issues. Will i get this problem? i haven't done a tooth count yet.

Also the from factory the speedometer is driven by cable to a converter box that then puts a signal into the dashboard (its a 80s digital dash). Could i convert the cable to electronic sensor (as were factory in later R154s) have that imputed into the link and a output to the dash? doing away with the cable and the converter box? that would allow me to adjust the signals slightly for speedo accuracy?

Thanks very much

Nick

 

[Scott]

Hi Nick,

It may be possible to tap into your ABS wheel speed sensors, it will depend on how happily the ABS controller accepts sharing the signal. If the ABS toothed disc is like most of them it will have too many teeth.  Here is some info I posted earlier as an example of tooth frequency:

500 Hz / 48 teeth = 10.4167 wheel revolutions per seconds.

For your wheel with 0.67 diameter you have a circumference of 2.04m, so you can do up to 21.2501 meters per second (10.4167*2.04), which is 76.5 km/h

If you halve the number of teeth your double the possible speed, so in the above example 24 teeth would allow 153 km/h. I think around 12 teeth would be ideal depending on your intended top speed.

We would need to know how the signal from the converter box to dash looks to be sure, but I think there is a pretty good chance you could make the speedo work from the ECU without the converter.

 Scott

[Nick]

Hmmm. well i hope that the factory abs module is happy sharing the signal with the link. It would be a shame if i couldn't run those functions

And i really want to keep the ABS in the car so modifying the tooth count is a no go.

If it does work, can you work the settings in a way that the launch and traction control work up to that 500hz frequency then after it hits it, Ignores the sensor until the vehicle speed drops back into that 500hz range like you say 76 odd km/h? So there would be no traction control above that speed?

Regarding the dash converter and speedo input, im going to pull it out in the next couple of days and ill do some testing figure out what range the converter works with

Thanks very much for your help so far

Nick

[mapper]

Hi you can use frequenzy multiplexer which divides the signal from the ABS Sensor. 

VEMS has such a unit. Quite cheap too.  It can be adjusted that id divides the signal by 8. Means traction controll can be used above 300km/h!  ;-)