Question on brakes
 

I'm getting ready to replace the brake pads on all 4 wheels. The rotors seem to be in decent shape, but have worn a little. There is a thin lip just outside where the pads have worn into the rotors---it's not much, certainly less than 1 mm (but probably more than 0.5 mm). I was talking to a technician at a local Porsche dealership and he said, while these rotors shouldn't be turned, he did say they could be put on a brake lathe and just have that lip taken down.

Does that sound like good advice? My kid wonders why that's even necessary, and I'm not sure I have an answer to that. Recommendations?

As long as that ridge is outside the brake pad surface, it's no big deal.
Shouldn't happen with OEM pads.

On some aftermarket (track) pads, it may be inside the pad surface, it will cut into the pad as the pad wears. I don't see it as an issue on my own car.

+1...ya check the pads you are putting on don't now overlap it. It maybe that the technician had that concern, or was just trying to make some extra $. If the pads are the same I wouldn't take the lathe to it, but maybe others can think of a reason. A lip of 5mm is not a lot, just about enough to catch your finger nail on, I can't see how it would effect braking.

A purist (like the Porsche technician) will always want to start with a perfectly good rotor surface so the new pads can bed in without any risk of problems. This ensures good braking performance and reduces the likelihood of the customer bringing the car back with a problem (one of the tech's biggest concerns).

A pragmatist will say that a 0.5mm lip is almost non-existant in the first place and is not likely to have any affect on braking performance and should be a fine starting place for bedding new pads. And the likelihood of actually having a problem is pretty low and even if you do, you can easily fix it.

Either apporach is generally acceptable and the answer you get generally depends on who you ask.

I'm of the thought you are better off resurfacing the rotor at the time you replace the pads. Of course you have to have quality rotors to start with. You don't want to resurface cheapo or Chinese rotors because they will warp in a heartbeat. Yes Porsche says you should not resurface theirs, but replace the rotors. Porsche OEM rotors are made of a high quality material and can take a little shaved off. I had mine done for $10 each at a NAPA store that has a very good machine shop. The machinist understood what I wanted and just barely shaved them smooth for me. They work great with the Posi Quite pads I purchased from Houston at Cquence.

The technician is correct. You don't turn these rotors. If needed, you replace them.

Replace them around 60K miles. I purchased Balo from Pelican Parts.

There really aren't any that can be turned anymore, they always dissipate heat poorly after that and are prone to warp which then leads to pulsing in the pedal.

He has an "S" meaning the rotors are cross drilled.
I don't think you can machine cross drilled rotors

You can, but the operator needs to be patient.