Chrono

I'm glad I took the wheels off to clean and inspect a few weeks ago. These pads were toast in my book. Cracked, pieces missing, and easily half the thickness of the backing plate. When does that sensor go off, when the backing plate is scraping? The wire (sensor) didn't have a rub on it.

DC911S

Looks like you need rotors too!

Chrono

I'm waiting to see if the new pads hone those ribs. The material thickness is OK.

Wayne Smith

Glad you caught it when you did.

halo777

Yeah, good catch

gota911

I am not so sure about that.

Obviously, I can't tell by the pic but that seems to be a rather large lower lip on the disc. If it is 1mm + and the other side of the disc is the same, then it is close to terminal, if not already there. Maybe that's why you don't have the wear indicators (dimples that we discussed in the other thread), because they are already gone. Just a thought.

DC911S

Thats what caught my eye too. Looks like a large lip. At least a few mm on that side alone.

jumper5836

Your sensor should have been ready to go off there. Was it even pluged in to the pad?

Well you can survive with a lot more rotor wear then that. Ever see what the thickness of a 4000 lb minivan rotors are.

BIG smoke

My sensors just went off on my wife's X5.
My job as car fairy is to extinguish all lights.
Dealer wanted almost $2ooo for the job.
I sourced OEM rotors, zimmerman and pads and sensors for $764 tax in.
My indy put them all on for 2oo bucks.
While I agree the rotor may look fine, can it be machined? Is that worth it?
My Zimmerman rotors were 120 front and 95 back. I would think they would be close to that for a porsche. How many miles on these rotors? I hate doing brakes. But I hate doing them again, so I tend to lean on spend a little more, do less often. Being a car fairy can be exhausting.

o/p good catch on the personal inspection. Your OCD cleaning revealed something of importance.

Macster

Only one pad (per wheel) has a wear sensor fitted. If pad wear is asymmetrical (and it can be) the pad without the wear sensor can wear faster and it is possible for the backing plate of the pad without the sensor and with the accelerated wear to contact the rotor.

Of course the noise arising from this would be as good or better than a warning light on the dash.

Nominally the sensor goes off when there is roughly 3/16" (0.187") of pad material left.

Macster

The general rule is for a rotor is it can be machined provided afterwards the rotor thickness is not under the allowed limit.

Generally though while the rotor may be thick enough the shop just doesn't want to bother as there is risk the rotor may not clean up and the shop will have to eat the cost of the surfacing. There is also the concern that even if the rotor ends up being thick enough after the surfacing it will wear under size long before the pads wear out.

I've done the brakes on my Boxster a number of times. Either the rotors are thick enough to reuse or they are not and get replaced along with the pads. I have never bothered to turn the Boxster rotors.

If the rotors are thick enough and in reasonably good shape they do not have to be turned when fitting new pads. Just fit the pads then take the car out and do a proper brake bedding in and this gets the pads and rotors matched right up.

Oh, if one rotor is not reusable and has to be replaced, the other side should be replaced as well to ensure both sides have the same braking capability and should have the same brake hardware life.

BIG smoke

I find most shops take off too much surface, when resurfacing. They often take too much of a swipe. Why do 2.5/1000th when 3.25/1000 will get it for sure. They can be in too much of a hurry. They are also charging for the machining. $8o bucks, $100? If it's only 240 buck for a new set of rotors? Like my X5, I often lean towards replacement. Are you a track rat? I'd want the thicker newer rotor.
Chrono- post pics of your new set up too. Cold and slushy here. Everything is filthy in 10 seconds or ten feet.

Chrono

Good thought, but no, that pic in the other thread was from a year ago. This pic, in this thread, is current.

Yeah, it was hooked up. Now it's tied back neatly where it works almost as well .

No, I haven't tracked it. And yes, new rotors are the way to go over machining. I've heard that these Porsche rotors should not be machined. Anyway, it's not the money, I just don't like wasting material. Those lips just exist on the right side, oddly, and even on the rear right with perfectly good pads! I attributed it to a seating issue but we'll see. They're stock with 33k miles.

flat666

cross drilled rotors cannot be machined. and my bet is as new pads wear into that rotor theyre going to get really noisy (partly because the edge of the pad will feather out a tiny bit as it wears and that edge contacting the lip will squeal) id replace them before grooving the new pads too deeply

semicycler

Not exactly true. They can be done, it just takes more time to do them properly with multiple passes taking very little material off each time. Most generic auto parts stores will not machine cross drilled rotors claiming they cannot be done. The reality is it takes too long for them to make money - it's a better deal for them to sell you new rotors.

I had my done by a local mom & pop shop, well within thickness/flatness spec too. The national chains wouldn't touch them though.