[ontheway]

Hi

From various searches here it seems that minimum thickness on normal 330 mm 328 rotors is the minimum thickness required to put another set of pads on. (assuming no other issues etc. )

Here in Australia, there is a general insistence in at least the few shops nearby that minimum thickness is an absolute minimum. I don't mind buying new rotors every 35k km but it seems like a waste!

Am I on the wrong track here? And does anyone have any official documentation from BMW?

Cheers

[Billfitz]

The minimum thickness, which is embossed on the hubs, is that for when changing pads. Usually when you change the pads the rotors are dinged and worn to the point that they need refinishing, usually referred to as 'turning' on a brake rotor lathe. So long as they're at least the minimum thickness after being turned they're OK. I wouldn't trust a shop that says otherwise to even wash my car, let alone do mechanical repairs.

Many Japanese and American cars can't have their rotors turned, because they were at minimum thickness out of the factory, to save weight and therefore increase fuel economy. BMW doesn't do that.

[ontheway]

Originally Posted by Billfitz

. I wouldn't trust a shop that says otherwise to even wash my car, let alone do mechanical repairs.
t.

Thanks. I agree although the level of initiative here in Australia tends to be low....

Anyway, after some more digging using leads on here I found the ref from the workshop manual.... For others...

-----
Front Brake F31
Important!

Installation of new brake pads is approved only provided that the brake disc thickness exceeds the specified dimension for "MIN TH" (see table).

Brake discs must be replaced when they reach the nominal thickness (see table) minus 2.4 mm!

(Not applicable to perforated brake discs and M vehicles)

.

Applies only to M vehicles and perforated ventilated brake discs:

The brake discs must be replaced once they wear to the nominal specified thickness (see table) minus 1.6 mm!

.

Depending on:

‐ Engine type

‐ Transmission version

‐ Equipment specification (e.g. maximum load increase, chassis official-use, national version, etc.)

different brake discs can be fitted

The brake discs must always be assigned by way of the relevant vehicle identification number and the Electronic Parts Catalogue!

Different thicknesses on brake linings Max. mm 0,01
Nominal size (diameter x thickness) mm 330x24
(MIN TH) is stamped in brake disc chamber mm 22,4
Nominal size (diameter x thickness) mm 340x30
(MIN TH) is stamped in brake disc chamber mm 28,4
Wear warning from residual lining thickness mm 3,7