The annoying break indicator for the rears came on. I checked and there is plenty of meat left on the pads and rotors are still fine. I installed a new sensor and zip tied it to the brake. Let'em grind i say!

 

OUt of curiosity, what do you mean the indicator came on. Is there an electronic warning of some kind? or are you talking about the scraping noise

 

agreed, zipped tied mine as well.

 

The low brake pad warning light/sensor activates when the rotor rubs against and breaks the sensor. That's all great but it does it with 20% of the pad still available for use. And the dashboard light makes it seem like your death is imminent.

 

What was the warning that came up? I believe there is some amount of leeway in the calculation so that when the warning comes on you still have some time to drive around and make an appointment at the dealer to get them replaced.

However, if you’re the kind of person that repairs his own brakes, then you have some time to order parts and plan out the replacement, too.

 

Had brake wear warning light come on in one car of mine. From experience I knew the pads still had 3/16th of an inch of material left. And I checked and pad wear was even. In some cases the pad can wear unevenly, more at the top (or bottom) or the leading or trailing edge. Bottom line is when the brake wear light comes on one just can't assume all is ok.

Decided to drive the car and see what happened. I learned how to avoid the light coming on at or shortly after starting the engine. At first the wear light came on very rarely. But then it came on more often. Still I drove on. Then it would come on every time I used the car. Then it would come on at engien start. There was no way of avoiding this.

I planned on continuing to drive the car but the warning light began to annoy me and I gave in and did the brakes. I managed IIRC around 2K miles beyond the initial brake wear light coming on.

Three of the 4 pads with wear sensor were wore down to the sensor and the sensors had some wear too.




Might also point out there was some signs of uneven wear. The top of the pads -- well, at least 3 of them -- wore a bit more than the rest of the pads. And one pad obviously had more pad material left than the other 3.

 

Did you see the pics? I had like 1/2 an inch left on the pads. Could be year before i need to change them with the way i drive.

 

You had plenty of life left in those pads.

 

Plenty is relative.

The wear sensors (in case of the car to which the pads came from) are 3/16th of an inch in diameter. So when the sensors make contact the remaining pad is thickness is (nominally) 3/16ths of an inch. However as can be seen in the pic at least 3 pads were worn enough to allow the sensor to make contact with the rotor and the pads were worn more at the top. There is a chance the wear at the top would not have remained constant and the wear rate would have accelerated and thus backing plate to rotor contact would have taken place. Or due to uneven wear and pad thickness the heat load difference would be too much and the pad material could experience failure and separate from the backing plate. Thus a pad goes from say 3/16th of an inch to zero inches in thickness in the blink of an eye.

The problem is the wear sensor comes on at a point there is still reasonable pad/brake life left so the brakes have a reasonable amount of safety margin and the driver doesn't have to immediately seek brake work. But if one continues to drive the car brake performance can suffer and the risk of a mechanical failure increases.

Thus to know the there is "still plenty of life in those pads" after the sensor comes on requires the brakes be periodically checked to hopefully know when there is no longer plenty of life left in the pads.

The braking system is a safety critical system. The pads/rotors are obviously a part of the braking system and one in which wear pretty much determines when they no longer have a suitable safety margin. While I wouldn't immediately park the car when the brake wear light came on I'd not delay too long in replacing the brakes.

While I did one time delay purposely delay attending to the brakes the experience was not without some anxiety. As I drove on I became less certain of the pad condition and remaining pad life. There was no backup wear sensor. To have to perform a brake pad check before every use was just not acceptable to gain a few miles more service life.

 

Mine look thicker than 3/16. That's all I can say....

 

Lex, your first picture shows the rotor thickness is 8.44mm, since the minimum thickness of the rotors (as stamped on the rotor) is 8.4mm, it's not the pads you have to worry about, it's the rotors. By the time your pads are worn to the minimum. 2.5mm your rotors will be under the recommended thickness.

The Powerstop rotor (with geomet coating), pad, and hardware kit (with new wear sensor) at Rockauto is less than $100.00 for my '09 Justa. I just changed everything (and the rear struts) because the struts were shot, and the rear rotors were at 7.4mm. The previous owner just kept throwing pads at it.

https://www.rockauto.com/?carcode=14...parttype=13824

You also should consider that with BMWs and MINIs the brake force distribution is more even than say, that average american car, which tends to nose dive under heavy braking. So, the rear brakes provide more stopping force keeping the nose of the car from pitching down.

 

Yes, but not that much. And with sensor not in the pad but instead zip tied up out of the way you have no way of knowing the condition of the pads (and rotors) going forward unless you periodically inspect the brakes. Or as you indicate let grinding noises be your alert.

 

8.4mm is the minimum rotor thickness you can add new pads too. Rotors are fine.

I had a new brake kit in-hand ready to install from RockAuto (POWER STOP KOE6281) but when I saw how much meat was left on the pads I said no way. This is stupid. Since the rotors cannot be cut on BMW's I don't care if they grind. Could be a year before those pads are down to the backing plates.

 

Well, that's the thing, you're not really supposed to drive them down to near the backing plates. Pads should be replaced when the material is about the thickness of the backing plate, say 1/4" or so.

Ze German car makers generally say to replace the discs when you replace pads. My personal experience is that that's bunk, and you can safely two sets of pads per disk. Just do the typical inspection and careful measurement to ensure the discs are in decent shape and above min spec.

 

Do you have one example, where this is the case (i.e. actual service instructions by a manufacturer)? Or is it just "advice" by service stations set to gain more profit?

For one, BMW/MINI specifies minimum wear limits of discs when replacing pads (here for the R56):

 

That is called "pad slap" in the industry...just slapping on some pads. Ive never done it, and brakes are so cheap when you DIY I don't think I would.

 

And this: "Since the rotors cannot be cut on BMW's I don't care if they grind. Could be a year before those pads are down to the backing plates." is why you should be legally prohibited from working on your car's brakes. Good grief what a silly disregard for your safety and that of your passengers and others on the road.

 

Well then you better stay behind me Rockie.