titanic

I have been hosing the rims to rinse off brake dust but I 've noticed lately that the circular discs just behind the alloy rims are turning rusty. Is this normal? Have I done something I'm not supposed to do?

UUronL

Don't do it to hot brakes. You risk warping the rotors.

radioham

hi ,well here goes the (circular disks?) are your brake disks that the brake pads rub against to stop(brake)you,
surface rust is normal and will rub off after a couple of miles driving.
i always run the brake pedal when its raining just before i get home to garage so that the disk is heated a little and will dry any moisture off.only because i may not use the car for a while.i always follow the same procedure after washing.hope this a help

DXXXi

I think he means the hub-housing(??) - the thing immediately adjascent to the rim that the rim actually bolts on to. This gets somewhat rusty on many cars and is most noticable on cars with more open style rims (liek 138s). I know it was a discussion topic in 2004 but not sure whether they have changed something to fix or not.

I don't think you can prevent it from not getting wet by not hosing it.

JayJay

Take it to a BMW dealer and tell them about it. I took my 5 to the local jetwash when i was being lazy and the wheel treatment stuff stripped off the silver finish on the bit you are talking about...IT went horrifically rusty and looked crap.

I contacted Damon Hill BMW in warwick and the girl in service asked me to email some pictures across so she would know what i was talking about. I did so and she phoned to say it wouldnt be a problem and i should just bring it in.

They applied some heat resistant silver spray stuff and assured me it wouldnt happen again. I have had no problems since doing so.

(picture attached)

titanic

No I believe those are the disk rotors, fairly huge disks which cannot be missed. Funny enough the rust kind of disappear after much driving around.

russo

No I believe those are the disk rotors, fairly huge disks which cannot be missed. Funny enough the rust kind of disappear after much driving around.
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Of course. Those are the brake disks that rust. Its normal to rust as they are made of iron. Even Ferraris and Porsches rust. Unless if its made of silicon carbide.

Reason why the rust disappears is because when you drive the car you need to brake. Therefore, when the pads clamp on the disc, it removes the rust as well. Rust takes place as soon as 30 mins after water contact as it is a pure iron. Don't worry about it.

However don't hose the wheels when its still hot as it'll warp the disc and have steering judder when you apply the brakes.