Minimum Brake Disc Thickness - how to interpret?

[Wp57a]

Thanks for all your replies.
I’m not at all suggesting that it’s OK to drive with poor brakes in any form.

What I am doing is highlighting what I see as an inconsistency in how the minimum thickness “spec” is applied..
Ie

- IF you say that there is a min disc thickness below which the car should not be driven
- Then…. When the pads are changed, there needs to be a HIGHER minimum thickness at that point
- Because if not, then if the pads were changed on the cusp of the min thickness, it is INEVITABLE that during the life of those pads, the disc will fall below minimum.

In that there is no min “pad change” disc thickness ever specified, we have to conclude that the manufacturers min thicknesses are set to allow for discs to be thinner during the life of the new pads.

Can there be any other conclusion?

What do you think?

[Gibbo2286]

I think you're getting into the realms of philosophy there mate..............or politics.

[furriegurrie]

I think you make an error in your thinking by linking pads and discs. Of course it is easier to change discs and pads at the same time and save some work hours. But you could just as easily put the extra hours in later when the discs are at their specified limit. That limit is just what it is, the minimum thinkness it should have according to the manufacturer to work as designed. Of course there is a certain margin, but you should not by default count on that and use it. In any case if you do it's at your own risk.

So change when at the limit or before if you suspect it'll reach the limit in the life of the new pads if you want to safe some hours/money.

[dnsey]

If you are changing the pads, and find that the discs are near minimum thickness, why wouldn't you change them as well? You've got to do some of the work in order to change the pads, and you'll need to change the discs soon anyway. All you could possibly gain is a few thousand more miles from the discs, in the course of which they are likely to 'sculpt' the pads so that they will need changing again too.
In practice, keep an eye on both pad and disc wear, and change both together before either has gone too far.