Re: Not to nitpick but

Hi,
These past couple of months the brake wear warning light has come on during driving.
It is off next time I drive it. It will be off for a couple of weeks or so, then come on again while driving.
This has repeated a few times.
Should I get a brake job ASAP or can I wait until the light stays on always?
Any idea how many miles I can drive before I need to get a brake job?
TIA

When the brake sensor like first comes on, you probably have 1/8" of brake pad left. So it is not urgent that you change the pads right away, but you should be moving in that direction. How far you can drive depends on how often and how hard you use the brakes.



Edited 1 time(s). Last edit at 01/29/2016 03:45PM by jg atl. (view changes)

Grant

gee-lenahan-at-gee-mail-dot-com

Now that the lights came on you will probably have to change the sensor too.

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boxsterd
Hi,
These past couple of months the brake wear warning light has come on during driving.
It is off next time I drive it. It will be off for a couple of weeks or so, then come on again while driving.
This has repeated a few times.
Should I get a brake job ASAP or can I wait until the light stays on always?
Any idea how many miles I can drive before I need to get a brake job?
TIA

Your mileage may vary.

When I decided to see how long I could drive my Boxster after the brake warnng light first came on I drove for a few thousand miles and was prepared to drive until the pad backing plate made contact with the rotor. But then the light would come on as I was backing the car out of the parking space at home or at work or any where really and was on essentially all the time. I tired of this situation pretty quickly and did the brakes.

IIRC the wear sensor is 0.187" (3/16th") in diameter. When I finally replaced the brakes the sensors were worn down to not quite half that thickness, call it 0.1". And just one sensor was worn this much. The others were worn too but not quite that much.

While this time I replaced all sensors I have in the past used a used one or more used sensors -- even though they had made contact with the rotor and triggered the warning light -- and the warning light didn't come on. However, I was prepared to replace the sensors if one/both started causing the warning light to come on.

Nowadays I just replace all sensors when I replace the pads/rotors.

Did you also replace the rotors or is that optional?

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boxsterd
Did you also replace the rotors or is that optional?

A few times when doing the brakes I've just replaced the pads and the hardware if the rotors are not worn down to their replace thickness. Of course when the new pads then wear down I have to replace the rotors along with the pads and the hardware.

On the outer edge of the rotors a lip develops.
When that lip is 1mm high then the rotors are worn.
Rule of thumb:
The rear pass and rotors last twice as long as the fronts.
The rotors should last through two sets of pads.
The above is valid when OEM brake components are used.
More aggressive pads will make the rotors wear quicker.
YMMV.
Happy Porscheing
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

That said, I question the value of trying to squeak out a few hundred extra miles out of 30k mile pads.

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Boxsterra
That said, I question the value of trying to squeak out a few hundred extra miles out of 30k mile pads.

There is no real value to continue to run the pads when the warning light comes on. The time I opted to do so I was just curious as to how long I could go and I decided since the pads were gone and the rotors too it would not hurt should the pads wear enough to make metal to metal contact with the rotors.

But really the wear sensors are there so that doesn't happen. One knows the pads (and possibly the rotors) are in need of replacement and while the hardware has plenty of miles still left, so there is no need to panic if this light comes on during a grocery run, one should avoid heading out on a 2K mile jaunt across the country.

If you were doing a 2K mile jaunt across the country, you'd spend most of the time on the highway and would be fine. I'd say on average you have 1000+ miles of mixed driving after the light comes on before it starts to get urgent.

I prefer to not head out on a long trip -- any trip really -- with a known issue with the car. While I continued to drive my Boxster with the brake wear light on I was close to home and in good cell phone coverage and handy to a back up car should the Boxster go down. Depending upon where one is on that 2K mile jaunt he may not even be in cell phone coverage when the brakes decide to go from just bad enough to trigger a warning to possibly something worse.

But I agree that likely a road trip that stuck to highways would be easy on the brakes. However, it is tough to ignore at least in my case any road trip of any real distance -- couple of thousand miles at least -- would probably end up having me driivng on highways that had lots of ups and downs and could see some pretty heavy brake usage because of it.

All wear items will eventually wear.

Not sure exactly what that means, really. The circuit in my experience is pretty simple - it either:

1. shorts to ground (rotor) which means the light should go on
2. the wire is broken/worn away, which also means the light should go on,or
3. All is well - the current flows with no short, light remains off

I guess its an intermittent short, which means this is early stage.

The simple answer is "take off a wheel and look" - its easy to see.

Another simple answer is "brake pads are cheap and easy, and you need them soon one way or another - get a set"

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Yes the light is intermittent. It was off for about week (daily driver). Yesterday it came on. It's off today.
The reason I'm thinking of not doing anything (unless it's a safety issue) is I may buy a new car end of the year.

.. is to pull the wheels, stick your head in, and look. Sometimes on pad wears MUCH faster than others due to accumulated gunk from brake dust, sometimes you have a long way to go. Aside from convenience of scheduling this for a good time, there is really no point delaying the inevitable.

But your eyes will tell you much more than that stupid sensor - which i by-passed years ago.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com