Brake pads & discs

red_eye

almillar wrote: »

I think there are a lot of unnecessary disc changes going on in this country. The disc shouldn't wear. I understand that pads are better and there can be more strain, and maybe more wear, but if the friction material hasn't worn out on the pads, the disc should be fine. If there's no lip at the edges, and no deep grooves or scratches (on both sides of course!) then the disc is absolutely fine.

confusing post you say discs shouldn't wear but the rest of the post contradicts, you say "If there's no lip at the edges, and no deep grooves or scratches (on both sides of course!) then the disc is absolutely fine" how is this possible if discs dont wear?

brakes use friction to work, friction without lubrication causes wear. So yes the disc should wear at a slower rate to the pads

So when would you change discs? when the disc has warn down to the thickness of a penny?

If you look on the edge of the disc there is a wear indicator in the form of a notch, if this notch is visible on the braking surface, or the disc is cracked, warped or has an big lip the disc should be replaced

You should not go around telling people that discs do not wear and that they do not need replacing when you do not know what you talking about.

almillar

OK sorry for the slightly confusing wording - I did say 'shouldn't wear' - perhaps I should have said 'designed not to'. Discs do wear, as I stated in the post. But the part that is meant to wear out is the pads. As I said originally, INSPECT the disc, it will outlast multiple sets of pads if they're changed on time and not subjected to track use or something. Did I not mention checking for a lip on the disc, I didn't say only change it if you can see through it!
NOWHERE did I say to run thin, cracked or scraped discs. This is about not getting ripped off by garages, and doing necessary work. Changing discs and pads every time is either bad driving, poor maintenance, or throwing money away.