Dealer has minimum rotor thickness specs?

[AutoXer]

I took my car in for rear brakes today and when I read the invoice after coming home, it read:

"Inspected brake linings. Front pads at 10mm, rears at 2mm. Rotors at 10.3mm, min=10.4mm. Remove and replaced rear pads, rotors, and sensor."

I had the front replaced 2 months ago and did not have comments like this. BMW has been replacing my brakes for the past 20 years and have never had anything like this. They have always replaced rotors and pads together.

So is BMW instituting a min brake rotor thinkness at this time? I wonder if my rotor thickness was at 10.5mm or 10.6mm, would they have turned it and reuse it? Anyone know?

[JCL]

There has always been a minimum rotor thickness.

Having said that, the rotors don't usually have enough metal left so replacing them is fairly standard. Turning them is not necessarily an option when they measure so close to the minimum thickness.

Not like some rotor designs that are so thick (and heavy) that you can always turn them down.

[Wagner]

Correct.

[Mackskibum]

When I did mine, the rears were able to be turned, the fronts were scrap. There is a minimum thickness cast into the rotor on the back someplace- usually in mm.

[chubyball]

The front rotors usually weird out quicker than rear one, I just replaced my front rotors and new brake pads myself on my montero sport @ 100K miles, it cost me $300. I wonder what is the mileage on your vehicle when you got your front rotors replace. I got 59K miles on my bimmer, the brake still good, but not when sudden stop the steering gets shake a lot more.

[LI_BIMMER]

In October BMW replaced my front and rear pads without replacing the rotors. I don't know if they were turned but recall the service rep telling me that the rotors didn't need to be replaced. My mileage back then was 28K and I now wonder if they will ever go back and check it for minimum thickeness since my warranty will expire in November 06.

[AutoXer]

I only got 18.6k miles on front and 21.6k miles in the rear. That's because I am cruising up and down the hills of San Francisco, and pads wear out alot quicker here. Same with all my cars.

Just odd that my invoices had that printed on it, and never before. That's all.

[Teutonaddict]

Originally Posted by AutoXer

Just odd that my invoices had that printed on it, and never before. That's all.

I've seen this on some of my prior work orders. I dunno if BMWNA is requiring better documentation, or you just had a more conscientious tech. I do think it's good you have a dealer that doesn't insist on pads and rotors at the same time (unless all are under or near spec). That tactic just seems like a dealer-money-maker to me. I could see scenarios where they do need replacing at the same rate, but that's likely the exception rather than the rule.

The minimum thicknesses are stamped on the hats of each rotor. I bought a brake micrometer to measure my rotor thicknesses, so I can alert my dealer to below-spec conditions whiles still under warranty. There's no reason you couldn't take your vehicle in for warranty rotors the moment you get readings below the spec.