How fast does your brake rotors rust?

[centurion]

Just curious. When my brake rotors are nicely rust-free, after a washing, taking 30 minutes, the rotors will be FILLED with rust.

How fast does this happen for you?

My manual says to drive the car aggressively to heat the brakes up to dry them up after every wash and I thought that was BS. Not now

 

[ryan]

Re: How fast does your brake rotors rust?

I was on a overseas weekend trip and my rotors were copper colored in about 2 days.

1/2 hour sounds a bit crazy though.

 

[Snail_Mobile]

Re: How fast does your brake rotors rust?

' 1/2 hour sounds a bit crazy though'

Its not really tat crazy, or maybe its the cheapo Japs, I used to c the rust form when I'm still drying the car after washed.

 

[jawzsg]

Re: How fast does your brake rotors rust?

Nowaday it has been raining in flashes, I notice that around 20 ~ 30 minutes after the rain has stopped, I start seeing rust spot on the rotor (mine's not aftermarket stuff) if I have been driving it during the rain. Not driving, it takes just a tad longer but fewer spots.

 

[centurion]

Re: How fast does your brake rotors rust?

just thinking - every time I scrape the rust off my discs with my pads, after 1 year need to change rotor liao.

 

[jawzsg]

Re: How fast does your brake rotors rust?

Hi CaySman, the rule of thumbs is have it changed after wear down 2 sets of pads.. I do not know the exact logic but I do use it as a guide.

 

[centurion]

Re: How fast does your brake rotors rust?

I'm utterly amazed at how fast it rusts. On my older cars it was taking many hours to rust, maybe days. Now, it's like MINUTES you can see rust spots and filled with rust in 30 min. Brembo uses crap metal? Or maybe, my brake pads are metallic and it's the pad layer on the discs which are rusting, not my rotors.

Is the rust brake rotor or pad material?

 

[jawzsg]

Re: How fast does your brake rotors rust?

IMO, all metal will corrode as it is a natural happening. Preservation techniques are employed to stabilize the exterior to allow it to have a lasting appearance. In the brake rotor situation, it is subjected to highly aggressive temperature and abrasive shocks, hence, this will wear down the 'coating' leaving the core metal in direct contact with the atmosphere, making it more prone to corrosion in the presence of moisture. The rubbing off effect is often termed run-in, hence your brake works better after the 'coating' is being removed.

Hence seemingly stable metal can loose its shine or start to corrode when subjected to prolong contact with acid/alkaline which may chemically removed it's protection (some such protection comes in the form of accelerated oxidation e.g. magnetide formation). In the case of hard water (water with large amount of mineral or grime being dissolved in it) a similar effect may occur by at a slower pace, depending on the type and amount of dissolved solid (normally termed TDS or Total Dissolved Solids).

Quite ironical though would be that pure to ultra-pure water can be equally corrosive to metal. This is mainly due to the high potential of hydrogen making fresh water acidic and its nature to absorb and dissolved matter. It is hence good to have distilled water in your battery as they need to move metallic ions from anode to cathode and vice versa accordingly to electrical polarity.

I guess at the end of the day if my rotor is not rusting after the rain, I may have to worry about my braking efficiency unless I am using rotor of other composite material such as ceramics.

My 0.2 cents...

 

[centurion]

Re: How fast does your brake rotors rust?

I thought brake `run-in' was the process of coating your rotor with the brake pad material, so that the friction will INCREASE on clamp.

Now my whole world is falling down when you say that run-in means that to take away the coating only.

From what you say it's my rotors rusting, but perhaps, is there possibility that my metallic brake pad material is rusting instead?

 

[jawzsg]

Re: How fast does your brake rotors rust?

The rotor is metal while the pad is normally a composite. While I understand how metal corrode I have not learn much about the pad material. I only know they fall of as brake dust in their course of usage. Its the friction force between these two items that help stopped our cars.

I believe the pad is designed to give more than the rotor to have both efficient friction and curbing excessive temperature build up... not very detailed... but seemed like a function approach. I do hope someone would step in to provide some enlightening for our benefits.

 

[VenomX2]

Re: How fast does your brake rotors rust?

mainly notice the vanes on the rotors look rusty after washing. you mean your whole rotor turns to rust?

 

[centurion]

Re: How fast does your brake rotors rust?

mainly notice the vanes on the rotors look rusty after washing. you mean your whole rotor turns to rust?

yeah, the WHOLE rotor becomes orange.

 

[Rastaman]

Re: How fast does your brake rotors rust?

yeah, the WHOLE rotor becomes orange.

No worries mate, i have the same thing happen to me everytime as well. Like u, i believe its the pad material, after washing just slowly dab the brakes and its off. Dun brake too hard coz if its (rotors) still wet the rust+water will flow down to yr new cleaned rims n dirty it again (if that happens, the just wipe it off using a piece of tissue/cloth).

 

[centurion]

Re: How fast does your brake rotors rust?

No worries mate, i have the same thing happen to me everytime as well. Like u, i believe its the pad material, after washing just slowly dab the brakes and its off. Dun brake too hard coz if its (rotors) still wet the rust+water will flow down to yr new cleaned rims n dirty it again (if that happens, the just wipe it off using a piece of tissue/cloth).

I actually go for a fast drive and left foot brake while on 2nd gear to dry up the brakes plus get rid of the dust. Not too concerned about rims getting dirty again, I wash the car not to make it clean but to ensure no long term dirt stays on the paintwork and eat into the paint.

I have a DIRTY white car most of the time, but at least the dirt is fresh (1 week old or less).

 

[martmode8850]

Re: How fast does your brake rotors rust?

happens to me all the time man... 30 minutes is all it takes to spot...

i want me brembos... hope life will not be the same again...

 

[kurqa]

Re: How fast does your brake rotors rust?

quite normal i think...seen many cars after washing with rust-like build-up on the rotors but after your 1st drive and some braking all will come off...don't think only BMW has this problem...seen recently on a friend's camry and some s-class