Rusty Disk Brake Rotors

Forums › Transport (cars, bikes and boats) › Rusty Disk Brake Rotors

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tweake

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#3437511 25-Nov-2025 18:10

rust is typically not an issue. seaside parked up for a long time maybe.

the worse is actually trailers. they rarely get used but i've never had issues with rust pn rotors. it gets cleaned off when you use the brakes. you can buy heavy galv coated rotors and the galv just gets ground off when you use the brakes.

the bigger problem is usually the hand brake being left on and the pads get stuck to the rotor.

gzt

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#3437513 25-Nov-2025 18:34

Rickles: 'molecular coating' implies not easily removed.

'Molecular coating' implies marketing ; ).

trig42

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#3437552 26-Nov-2025 08:44

The second Auckland lockdown in COVID caught me out - I had left my car at work on the Tuesday night, and we went into Lockdown on the Wednesday. My car was left outside at work for about 4 weeks.

When I got back to work, all the discs had a coating of rust.

By the time I had driven it back the carpark it lived in (about 20 minutes) they were clean and shiny.

Linux

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#3437553 26-Nov-2025 08:53

trig42:

The second Auckland lockdown in COVID caught me out - I had left my car at work on the Tuesday night, and we went into Lockdown on the Wednesday. My car was left outside at work for about 4 weeks.

When I got back to work, all the discs had a coating of rust.

By the time I had driven it back the carpark it lived in (about 20 minutes) they were clean and shiny.

Cause it is just surface rust and would be removed by the time you left the carpark! Anyone thinking of spending $$ to stop surface rust on discs got far to much money!

Edit: removed comment

Rickles

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#3437554 26-Nov-2025 09:05

@Linux ... thanks for your opinions, but is not this Forum a 'safe place' for asking questions and seeking advice, rather than being ridiculed?

Asteros

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#3437555 26-Nov-2025 09:05

There is nothing wrong with having "too much money." It is preferable to having "too little money" from hard won experience.

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Linux

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#3437556 26-Nov-2025 09:16

Rickles:

@Linux ... thanks for your opinions, but is not this Forum a 'safe place' for asking questions and seeking advice, rather than being ridiculed?

Sorry I take that back but please don't worry about surface rust on disc brakes find something else to spend $$ on

You could spend it on me if you like 👍

Bung

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#3437559 26-Nov-2025 09:55

On the outer edge(s) of the swept area you can get rust that's more than surface. It can get bad enough to wear the pad at the edge. The shiney braking surface gets narrower. The rust at the edge will probably stop any attempt to skim the disc surface.

Apologies for picture quality, this is one front disc on a Subaru. The other side looks like 1 rotor has already been replaced.

gokiwi64

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#3437659 26-Nov-2025 12:56

I have 80% cast iron in my rotors on my Commodore, they rust like crazy but after two or 3 good braking applications clean up nicely , the unswept outer edges will always look far worse but if the lip is not significant this can be cleaned up with a skim (there might even be a mobile service that does this in your area).

Alternatively if not to bad you can clean them up yourself with a couple of grades of scotch brite and brake cleaner.

For reference - https://www.advancedbrakeskimming.co.nz/

Rickles

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#3437660 26-Nov-2025 13:04

Thanks all .... I'll try simple brake-clean with a rag, and then ensure I brake more often <😁>

gokiwi64

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#3437663 26-Nov-2025 13:14

Couple of other things to mention - Dont forget to do the inside of the rotor and if cleaning up the swept surface dont go around the disk but at right angles to the rotor.

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richms

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#3437672 26-Nov-2025 13:25

Also depending on what you take off you will need to bed them in again which is best to do before you really need them, as it will still stop gently fine with a plain metal surface there.

Richard rich.ms

alertbuildinginspect

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#3446096 20-Dec-2025 20:36

I've used it and it was ok

Goosey

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#3446121 21-Dec-2025 07:49

Show us a photo…

also, when’s the last time you had rotors replaced and what did the mechanic replace them with.

with car parts not all are equal…..you get OEM, then aftermarket and the aftermarket come in all different qualities.

if you are keen to spend money then specify to the mechanic to fit Brembo or similar….. obviously comes at cost but these would be better than the bog standard aftermarket replacements.

unless you are half an hour away from each and every coastal boundary of NZ….salt water is an issue.

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