Brake discs rusting
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sevenhills
Posts: 5,885 Forumite
in Motoring
Why do brake discs rust?
I have one disc that is rusting on the edge, as others on here have had similar issues, I thought I would ask if it be avoided.
I recently put new pads in, cleaned the disc a little with emery paper and a file. But the rust is still a thick ridge.
As I have alloy wheels, I can see that because the disc has a ridge, the new pads are not touching a small section near the rust, so the rust will be spreading.
Not sure if it would have been practical to remove the discs, with the pads (Megane 2006), but renewing the pads is making the rust worse.
I changed the pads about a month ago, and the pads have not yet worn past the ridge of rust. At the moment, the rust is minor. the car has recently past its MOT.
I have one disc that is rusting on the edge, as others on here have had similar issues, I thought I would ask if it be avoided.
I recently put new pads in, cleaned the disc a little with emery paper and a file. But the rust is still a thick ridge.
As I have alloy wheels, I can see that because the disc has a ridge, the new pads are not touching a small section near the rust, so the rust will be spreading.
Not sure if it would have been practical to remove the discs, with the pads (Megane 2006), but renewing the pads is making the rust worse.
I changed the pads about a month ago, and the pads have not yet worn past the ridge of rust. At the moment, the rust is minor. the car has recently past its MOT.
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Comments
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sevenhills wrote: »Why do brake discs rust?
I have one disc that is rusting on the edge, as others on here have had similar issues, I thought I would ask if it be avoided.
I recently put new pads in, cleaned the disc a little with emery paper and a file. But the rust is still a thick ridge.
As I have alloy wheels, I can see that because the disc has a ridge, the new pads are not touching a small section near the rust, so the rust will be spreading.
Not sure if it would have been practical to remove the discs, with the pads (Megane 2006), but renewing the pads is making the rust worse.
I changed the pads about a month ago, and the pads have not yet worn past the ridge of rust. At the moment, the rust is minor. the car has recently past its MOT.
It's probably something to do with them being made from iron.0 -
Warwick_Hunt wrote: »It's probably something to do with them being made from iron.
Many just wear out.0 -
Warwick_Hunt wrote: »It's probably something to do with them being made from iron.
.......and made worse if the OP doesn't do many miles.
.......and as it's an 11 year old Renault that's quite likely.0 -
Fit new discs sorted until next time.Censorship Reigns Supreme in Troll City...0
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forgotmyname wrote: »Fit new discs sorted until next time.
I'll second this. Discs do wear and get rusty, it's a fact of life. They're also cheap and very easy to replace on most cars.0 -
forgotmyname wrote: »Fit new discs sorted until next time.
So my car has surface rust on the discs after 24hours, should I change them?
Or just take the car for a spin and clean the surface rust off?
New discs with only a few thousand miles on
and it`s a known issue on this model and many others. 0 -
Light surface rust that gets rubbed off after a few miles/applications of the brakes is normal and not a problem.
I think that the OP's problem is that there is a wear ridge on the outer circumference of the disc that is preventing the new pad from contacting the disc surface near the ridge.
A visible ridge that cannot be sanded or filed off likely means that the disc is at or near the wear limit / minimum thickness.
All discs have the minimum thickness stamped on them - perhaps difficult to see or read after corrosion has set in though.
If I was the OP I would have fitted new discs at the same time as changing the pads.
As Ebe Scrooge has said they are cheap and easy to replace these days.
Some vehicles discs do tend to rust more than others - on my Freelander 1 for example I needed a new set of discs every 2nd pad change.0 -
The rusting of discs does seem to vary with different vehicles I have a fairly new Fiat and an anchient SUV that do similar miles. The Fiat has been through 2 sets of discs due to rusting while the SUV is still on the originals.0
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We live in the UK, and it has been raining a lot lately.
Rain is composed of water and various other trace elements, including salt.
Brake discs are usually made from cast iron, and this metal does not like water, because water turns it yellow, then orange and finally a crusty brown colour, which then makes the metal corrode and fall apart.
Lewis Hamilton and the other racing drivers get around this by fitting carbon ceramic discs, which do not rust, but which are very expensive.
Fortunately, Lewis and the others don't have to pay for them.
The only way to stop discs going rusty (apart from moving to the Atacama Desert), is to use the car every day and to gradually increase the braking pressure.
When you get home, the discs will look all shiny again.0 -
The rusting of discs does seem to vary with different vehicles I have a fairly new Fiat and an anchient SUV that do similar miles. The Fiat has been through 2 sets of discs due to rusting while the SUV is still on the originals.
Perhaps if some cars have pads that leave and extra couple of mm disc showing, it can allow the rust to start?0
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