This thread made me think about my brakes again; and in particular the post showing the rusty disc.
I refurbished mine in around early 2020. The discs had been rusty until then and and it seems to happen when the callipers stop working properly - maybe due to rusting. And as mentioned before the callipers also seem to stop working when the pads wear to about 1-2mm, or at least that is the case with mine.
So a rusty disc seems to denote a faulty calliper. During a recent check, one of my rear discs has rusted again whereas the other is bright. The rusting has occurred in the last few months. During the refurbishment I fitted new seals and pistons, mainly because the old pistons had traces of surface rust and pitting.
So now the question is 'what is the state of the calliper with the rusty disc?'
I will check in due course and report back.
The last time I had problems with brakes was with a Peugeot 205 with Bendix callipers. I discovered that there was a Girling upgrade; they not only actually stopped the car but didn't give any trouble in the subsequent years of owning the car.
I don't like the design of the Honda callipers. They are designed to fail. It would be nice if a replacement design was available.
I have only ever had problems with rear discs on Jazz ( or any other car, the front discs seem trouble free ) the rear wheels and brakes get all the rubbish thrown up by front wheels, and disc brakes are so open the stuff gets into the mechanisms. Discs have no place on the rear of a small car, they contribute very little ( <15% ) to total braking force, make a cr4p handbrake and wear out too quickly. On previous Honda cars with rear drums the shoes lasted >100,000 miles, and the drums will outlast the rest of the car, which discs never will.
I have had rusty rear discs on MK2, and it was not the fault of calipers, I went through 2 sets of Honda discs and pads in 4 years ( due to very heavy rust ) and since fitting Eicher discs and Brembo pads from Eurocarparts ( no change to calipers ) the rear discs have remained shiny. Seems that the Honda materials may be the problem., they were genuine Honda from Cox Motor parts.
The best preventative maintenance on calipers is changing the brake fluid at least every 3 years, the fluid absorbs water and many caliper failures are internal corrosion of cylinders due to water in system. I doubt very much if brake fluid ever gets changed during services, so if you get a second hand car even with FSH i would flush the fluid.