Rusty Rear Brake Discs

[JohnF]

My car is a 2002 IS200 which I’ve owned from new, and about 2 years ago I fitted new (Mintex) discs and pads all round.

At the weekend I noticed the rear discs were a bit rusty – not unusual at this time of the year, but the rust normally gets rubbed off very quickly. I took the car for a short run and applied the brakes hard several times, and when I stopped the rear discs were still rusty in parts and the rust was now polished. The discs were warm to touch but not hot.

When I got home I checked the pads, plenty of wear left, and whilst the wheels were off checked that the rear brakes are in fact coming on. The pistons can be pushed back in their cylinders, and return to normal and lock the wheels when the brake pedal is pressed. It’s as if pressure is being applied, but at reduced pressure – is this possible? I know very little about ABS by the way.

If anyone has any ideas what is wrong I would be grateful to hear from you.

[The Swede]

My car is a 2002 IS200 which I’ve owned from new, and about 2 years ago I fitted new (Mintex) discs and pads all round.

At the weekend I noticed the rear discs were a bit rusty – not unusual at this time of the year, but the rust normally gets rubbed off very quickly. I took the car for a short run and applied the brakes hard several times, and when I stopped the rear discs were still rusty in parts and the rust was now polished. The discs were warm to touch but not hot.

When I got home I checked the pads, plenty of wear left, and whilst the wheels were off checked that the rear brakes are in fact coming on. The pistons can be pushed back in their cylinders, and return to normal and lock the wheels when the brake pedal is pressed. It’s as if pressure is being applied, but at reduced pressure – is this possible? I know very little about ABS by the way.

If anyone has any ideas what is wrong I would be grateful to hear from you.

I'm no expert either but it seems that the rust ate in a bit deeper than just giving a bit of colour on the surface.

That being said, the rear brakes always apply much less pressure than the front ones and when it's cold and slippery, you're not tempted to really brake hard enough to use them properly.

I would just take it for a proper drive and REALLY hammer the brakes so they get very hot.

[JohnF]

Thank you The Swede, I feel sure you are correct. The car hasn’t been used much for the last month and looking at it more closely the rust is just a bit more than the normal surface rust. I’m not a hard driver by nature but we went shopping this morning, about 16 miles round trip, and a lot more rust has come off the discs I’m glad to say.

It also gave me the opportunity to have a good look at some of the cars in the supermarket car park and I saw quite a few cars with rusty rear discs, so I’m now more confident that I don’t have a problem. Many thanks again.