Speed sensor removal

[Paul Fraser]

While trying to remove a speed/abs sensor in my '97 Boxster it broke in half as it had become well and truely stuck in the hole. Surprising as the sensor is plastic cased... I have subsequently been trying to dig/drill it out but have gotten nowhere.

Anyway, I am now planning on removing the wheel hub and dismantling so I can hopefully knock it through the hole it is in.

Can anyone confirm that if I remove the tension bolt (5) I will be able to do this, i.e. that the hole isn't blind? I assume the reason the tension bolt has a toothed circumference is that this alters current produced by the magnet in the sensor and so provides a signal to the ABS unit?

[seafeye]

While trying to remove a speed/abs sensor in my '97 Boxster it broke in half as it had become well and truely stuck in the hole. Surprising as the sensor is plastic cased... I have subsequently been trying to dig/drill it out but have gotten nowhere.

Anyway, I am now planning on removing the wheel hub and dismantling so I can hopefully knock it through the hole it is in.

Can anyone confirm that if I remove the tension bolt (5) I will be able to do this, i.e. that the hole isn't blind? I assume the reason the tension bolt has a toothed circumference is that this alters current produced by the magnet in the sensor and so provides a signal to the ABS unit?

Yep you should be OK. This pic should help. What you see through the hole is the tool i was using to remove the wheel bearing.

Edited July 27, 2009 by seafeye

[ericinboca]

While trying to remove a speed/abs sensor in my '97 Boxster it broke in half as it had become well and truely stuck in the hole. Surprising as the sensor is plastic cased... I have subsequently been trying to dig/drill it out but have gotten nowhere.

Anyway, I am now planning on removing the wheel hub and dismantling so I can hopefully knock it through the hole it is in.

Can anyone confirm that if I remove the tension bolt (5) I will be able to do this, i.e. that the hole isn't blind? I assume the reason the tension bolt has a toothed circumference is that this alters current produced by the magnet in the sensor and so provides a signal to the ABS unit?

Yes, it is a through hole. Not sure how the sensor works, but if you get the wheel carrier off, and the front short axle out, you will see it. Very tight quarters in there, though.

[RFM]

All wheel sensors including MY 04 are inductive (classic), from MY 05 Porsche use a different system on the sport cars (the same system as Cayenne)

[wvicary]

The wheel speed sensors are of the permanent magnet type and produce a AC signal. One reason they are difficult to remove is that the iron core on the sensor can rust and swell causing it to seize in the housing.

[Paul Fraser]

OK, had another look at this tonight. Put the wheel on and took the Jesus nut off. The tension bolt came out easily, and better, far enough so I didn't have to take the shock absorber off. After I turned the hub (wheel off again) to the left I had good access and after a couple of good swings at a drift with a large hammer the remainder of the sensor popped out. The tension bolt goes back far enough to retrieve the remainder from the rear of the hub.

New sensor fitted after cleaning the hole with a piece of sandpaper, Also put a skim of copperslip around the circumference of the sensor.

My Durametric shows that the associated code had cleared leaving me one on the back right which I think is a wiring fault. I hope so; I can see that being more problematical otherwise.

Edited July 28, 2009 by Paul Fraser