Brake Sensor Light and New Pads?

[Exactmax]

Hi People,

Got in the car yesterday and the brake sensor light came on on the dashboard. Now I understand that there is a sensor mounted on the brake pad that once worn down needs replacing along with some new pads... What I would like to know is the following;

How can I tell which sensor(s) has been worn down?
Should I replace all the pads at the sametime?
Is it worth getting new rotors aswell (how can I tell if these are worn aswell)?
How long do I have between the sensor coming on and the pads needing to be replaced?

I have looked at other threads here on the forum and I can't come to a decision on weather to go for Redstuff/yellowstuff or greenstuff pads or just replace with OEM? I've read that they can rattle once fitted and thats the last thing I want.... I've been looking at this companies website for the rotors and pads http://www.europerformance.co.uk/pages/products/product_info.mhtml?product=3938272

Are these the right sensors for the pads? http://www.ebay.co.uk/itm/BMW-E46-M3-Z4-REAR-BRAKE-WEAR-INDICATOR-WIRE-SENSOR-/250856007874?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3a682ee8c2#ht_1640wt_905

Thanks for your help people and if anyone has any new rotors fitted that are either grooved or drilled then post some pictures

Thanks,
Max

 

[cj10jeeper]

Lot of questions in one post

Wear after the sensor comes on depending upon use, butI'd say a few hundred miles. I did a weekend event with the light on and still some pad left
Best way to tell is a visual inspection of pad thickness through the wheel. It should be easy to see which are worn.

No need to replace rotors unless they are thin (often seen with a big lip on the outer edge), scrored or cracked

Sensor you link to looks correct. I bought off ebay and it is fine. You need one side only and one front/rear depending upon which is worn out.

Pads- no right answer. I use Greenstiff and they are excellent. Some prefere red, but I'd keep away from yellow. soem have rattle but mine never have. OEM is easiest to go with but dusty and expensive at dealers.

Hope that helps

 

[Exactmax]

Thanks for your feedback! So from reading your post I just need one sensor for the front and one for the back (not a sensor per wheel)???

Got back in the car and the light has now gone off? Not sure what's going on now!!!

 

[Wondermike]

Could have been low brake fluid, were you on a hill when you saw the warning?

 

[Exactmax]

When the light first came on, the car had been parked on a curb so no real slope. The light didn't go off for the journey home (about 40mins). Moved the car this morning and the light was still on. Moved it again just after lunch and the light was off??? I'm not sure when the pads were last changed.

If I do go for Greenstuff pads then is it worth changing all the pads not just the front?

 

[cj10jeeper]

The sensor will come on then off a few times. Happened to mine. It sort of averages out so it's not flashing on and off.

Coronet one front and one rear sensor only

Change all pads for proper balance of the system if you change makes

 

[Exactmax]

I noticed on ebay that there are two different lengths of the brake sensor cable?

http://www.ebay.co.uk/itm/BMW-E46-M3-Z4-REAR-BRAKE-WEAR-INDICATOR-WIRE-SENSOR-/250856007874?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3a682ee8c2#ht_1640wt_905

or

http://www.ebay.co.uk/itm/BMW-E46-M3-Z4-FRONT-BRAKE-WEAR-INDICATOR-WIRE-SENSOR-/290593984836?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item43a8c05144#ht_1640wt_905

Do I need both lengths or just one of two lengths?

 

[cj10jeeper]

The ebay descriptions clearly show one to be a front and one a rear. You need on of whichever you have to replace

 

[Exactmax]

Is there a good place to get Redstuff pads from? I've looked at this website http://www.europerformance.co.uk/pages/products/category_results.mhtml?category=ebcredstufffrontpads&car=bmwz4&manufacturer=ebc&sub_category=1 and they appear to be quick good... Any recomendations on where to go for them?

I've also seen that anti-abrasion stuff should be applied to the brake when putting back together and anti-rattle soloution? Any ideas where I can get that from?

Thanks for all your help so far

 

[Exactmax]

Since posting this topic, the brake light sensor has stayed off? I thought if the sensor came on then it stayed on as it's broken the circuit?

 

[cj10jeeper]

Since posting this topic, the brake light sensor has stayed off? I thought if the sensor came on then it stayed on as it's broken the circuit?

I heard the explanation that they record the contact over a period of time else as braking wore the pads to the point of contact it would flash on and off as the sensor made partial contact to start with. Mine did exactly this - came on and then off over a week,

Truth is it and the pads are shot and needs replacing. Only cost £6 on eBay.