When a brake wear sensor is triggered, how many miles (normal driving) until the pad material is gone and the rotors start scoring? I know mine are getting there and I just bought new pads, rotors, sensors and caliper bolts.

My pad material is about as thick as the backing plate right now on both fronts & rears, so sensors will trip soon. I may be splitting hairs here but here are 3 scenarios:

1. I could just replace pads and rotors now before the sensors trip and reuse the sensors (send new ones back for refund), eliminating having to replace them. Not that they are costly.

2. Let the brake pad sensors trip and then replace rotors, sensors, pads all around immediately.

3. Let the brake pad sensors tip and continue driving until the pad backing plate hit the rotors, then replace rotors, sensors and pads all around. (This is why I ask the first question.)

Since I only put between 2,000 & 3,000 miles per year, option 3 may make sense. If once the sensors trip there is 5 or 6 thousand miles before the pads hit the rotors, that could be 2 or 3 years more of life in the old brake pads. If only 1 or 2 thousand then maybe just replace everything once sensors trigger.

Any safety issues going with option 3?

 

Option 2 sounds like the best decision.

When the sensor hits you are down to 1 or 2 mm left. It all depends on driving styles but usually less than 1k miles is expected.

 

 

Only 2 responses so far, but I have a feeling option 3 is out.

 

Wait till you see sparks coming out of your rear wheels from the side mirror then you know for sure the pads are completely worn out

Kidding aside, I like option 2 followed by option 4.

 

Let me also add that running he pads to metal to metal causes the caliper pistons to be pushed out further than they should be. It's not work the risk of damaging expensive calipers not to mention the safety aspect. Too many times i have seen cars come in with pads actually missing and the caliper piston is contacting the rotor - that's when the customer says "it only started making that noise a few hours ago".

 

That would be BAD ***, especially at night.

 

 

If I recall correctly, my brakes squeaked pretty loudly as the sensor materials started just peeking through and touching the discs. I drove it about a week - it didn't trip the sensors and I was able to reuse the sensors.

 

I did my brakes last summer at option 2. I really like having brake pad material when stopping my car vs metal on metal. New rotors, pads, sensors and misc bits. Plus SS brake lines since was still on original rubber hoses.

 

New pads have about 10mm pad thickness, the wear sensor is set at about 2mm.

I have seen people wear out a set of pads in a couple of DE track days, I have also seen people drive 100k miles on their original pads.

For most people, when the wear light comes on(2mm), there is no need to re-arrange your whole life to get your brakes done, (ie. take off work, cancel your doctors appointment, ect ) but you should plan to get them done at your earliest convenience.

 

Why are you replacing your rotors? Are they worn thin past the wear limit or are your brakes pulsing in some way?
To me, the normal thing to do, as long as your brakes are not pulsing/vibrating, is to run them until the sensors come on, then change the pads, and check the rotors for thickness and excessive scoring, etc, and if all is well, keep going.
After you do this job once, you will see that Porsche has made it very easy to change pads. Once you have your wheels off, it's like a 2 minute job. What I'm sayin' is, no reason not to just have a look at everything before you buy, and then don't buy stuff you don't need.
But, that's just me.

 

 

I use the Boy Scout method, "be prepared." Over a year ago I inspected my complete braking system and determined my brakes were going to need replacing soon. Pads F&R were nearing minimum thickness. Rotor thickness both F&R were below minimum thickness spec. I buy parts proactively on sale and during deep discount holiday sales. So in a nut shell I knew what shape my brakes were in over a year ago, estimated about when they might need replacing, then shopped the parts that i knew would need replacing during the year before I estimated doing the job.

 

Just so everyone can sleep at night.

Going with option #2. Let the brake pad sensors trip and then replace rotors, sensors, pads all around immediately.