wierd wearing pattern on rear discs

[KnifeEdge_2K1]

on my brother's 98 accord's rear discs there's an extremely wierd weareing pattern on both wheels

the outer edges of the discs are completely corroded (not just the edge, the disc surface itself from the outside extending almost to the halfway point between the outer and inner circumference of the brake disc) while the inside is completely shiny

what i think is that when we got the pads replaced the mechanic placed it improperly at an angle causing the only the inside of the pad to make contact with the disc and the outside remaining exposed

regardless of the cause of this problem there is no doubt we will need to replace the disc and pads, is there any other component I should check before we go through with the replacement ?? brake lines ?? caliper ?? wheel allignment ?? anything ??

on a seperate note the accord's braking performance has been degrading steadily over the past couple years, when i first started driving the accord had the best brake feel and shortest stopping distance of the cars at my household but right now even my corolla which has rear drums have better response and what seems to be shorter stopping distances ... please advise

[Matra et Alpine]

Creeping rust from the edge of a disc is a common problem in countries where roads are salted.

The lip prevents the pad contacting the disc effectively which accelerates it's growth. And makes it progressively get worse as you experienced.
It also means the pads move firther away from the disc whilst non rbaking so that when you press the pedal it can be very soft as it takes up the larger gap.

A decent mechanic would NOT have fitted pads with the disc in that condition

Regular cleaning of the rust lip helps prevent it's growth.
Once it's that bad though you need to get them skimmed or replaced - the latter being so cheap nowadays that it's the better solution.

Replace the discs and pads and it will be fine.

[Daz27]

Is it doing it on both sides of the rotor out of curiosity?

[KnifeEdge_2K1]

i havnt seen the other side of the rotor but i assume it's probably in the same condition

[Daz27]

Ive never heard of creeping rust.... is it on both rear rotors?

[Matra et Alpine]

Ive never heard of creeping rust.... is it on both rear rotors?

WHere in Aus are you ?
IN a very dry climate I could believe it.
Anywhere near sea or damp or salt on roads then they all do it - LOTS

[Daz27]

Sorry Matra, just sayen I personally havent come across it. Ive lived on the coast most of my life, and inland, smack dab next to a salt lake for a month too with friends on holiday, spending every chance we had outside carving the salt up in our cars, and any rust that ever formed on the rotors was gone on first application of the brake. Makes me think of all those morons who sit there with emery tape sanding back the surfaces of their rotors when they replace the pads, thinking its doing good... Hmm, flywheels too... First application of either and the hard work and blisters are wasted...

[Daz27]

Ive just read somewhere that undersize rotors can do this too....