Wheel Speed sensor - side reading

[Grant Baker]

Hi

Does anybody know of a wheel speed sensor that can pickup on the magnetic ABS rings in BMW hubs?

The "stock" sensors are a bit smart and don't work with ECUs without considerable effort (don't actually work at all to be honest).

To simplify things, we'd like to get a sensor that is at least 40mm long and picks up from the side of the sensor rather than the end. 8-10mm in diameter.

Pickup Surface is 25mm from the mounting face and is 15mm long.

[Confused]

On a G4+ Xtreme, the ABS rings will probably have too many teeth to give you working value at higher speeds.

What you may be able to do, though, is pick up on the back of the brake disc/hub on the wheel studs, for example.

This is the little bracket I made for my front wheel to pick up on the back of the wheel studs:

[Dean]

I went through a similar process with a 370Z ABS sensor (active speed sensor) and used this document to help -- https://www.motec.com.au/filedownload.php/CTN0007 Magneto Resistive Sensors.pdf?docid=3634

 

I used the standard ABS sensor with 8V going to the positive side, and a 150R pulldown resistor in the ground. This got me a voltage oscillation range of 1.02-2.11V which the Link ECU can read through a digital input. The G4X is capable of receiving a higher frequency than the G4+, so using an ABS speed sensor seems to work well.

I’ve previously used ABS sensors on a Fury G4+ up to 260kph without a problem   

 

[Grant Baker]

Hi

This is on a Thunder... So no issue with frequency.

Dean - did your 8v and pull down filter out the "odd" lower voltage pulses ok?

So you used 8v to feed the sensor and 150Ohm resistor pulldown on signal wire?

[Dean]

10 hours ago, Grant Baker said:

Hi

This is on a Thunder... So no issue with frequency.

Dean - did your 8v and pull down filter out the "odd" lower voltage pulses ok?

So you used 8v to feed the sensor and 150Ohm resistor pulldown on signal wire?

Yes. Like this..

I don't think my type of sensor has the odd lower voltage pulses, it just oscillated between the two voltages. 

 

I just kept trying different voltage supplies (5V, 8V) and resistors in both pull up and pull down configuration until I got the result that worked. I lost confidence along the way but glad I persisted. A little resistor and some wiring is way cheaper than redoing the whole speed sensor setup.

[Grant Baker]

Thanks.

On a Thunder, the DIs are Differential, so have + / - dedicated pins.

Just trying to work out the wiring for the above on a Thunder? 

[Dan Bloomfield]

On 2/12/2021 at 9:02 AM, Confused said:

On a G4+ Xtreme, the ABS rings will probably have too many teeth to give you working value at higher speeds.

What you may be able to do, though, is pick up on the back of the brake disc/hub on the wheel studs, for example.

This is the little bracket I made for my front wheel to pick up on the back of the wheel studs:

Do you think it would be posable to shave every second or second and third tooth off to have half or a third of the original amount remaining 

[Confused]

If there's a suitable number of teeth to be able to evenly divide it by, then possibly.

An example where it won't work - Mitsubishi ABS rings, where there are 43 teeth per revolution. This is a prime number, so there is no way to remove any combination of teeth and be left with an equally spaced set of remaining teeth.

Or, you could use a frequency divider circuit, there's examples been posted elsewhere here on the forum before.