Brake question

[Raprider]

Had my front wheels off recently and noticed these rust spots on both of my front discs, same place on each side. It is about 2 inches long, smooth to the touch.

2016 ST-S purchased new in Jan 2018...currently about 9k miles...and I do get some brake squeal at low speeds.

Thoughts?

[Peter Aawen]

That sort of 'brake pad rust mark' rarely causes brake squeal & is usually caused by the vehicle been left sitting for a while without movement. It happens on pretty much every vehicle that sits for a few days; it starts to happen the moment you stop; and it will occur quicker if you've been riding/driving in the wet extensively but without any hard braking to heat up & boil off the moisture that accumulates in the pads thru use. It occurs because the tiny gap between the pads & the disc make for an ideal environment for mild surface 'rust' to start. It's normal, it's not usually damaging, and it's to be expected if your vehicle sits between uses, only most generally don't notice it because the 'discoloured patch' is hidden by the pads until you start moving again, and by then you're on/in the machine & the first few applications of the brakes will usually wear it off pdq!! If it's a bit more than what you get after a couple of days standing, it can contribute to the brakes squealing a little until the pads/discs wear in again, and if it's really REALLY bad, it can require the removal of the pads & scuffing their surface with fine sandpaper.... but that's usually pretty rare.

However, if your vehicle has been left sitting for longer than a couple of days &/or left with wet pads in a humid environment it'll appear. If it bothers you, just find yourself a clear straight stretch of road & when there's no traffic you can annoy or put at risk by doing so, take your Spyder's speed up to saaay 30-40 mph and (after checking behind to make sure it's safe) firmly apply the brakes so you slow rapidly down to about 10-15 mph then ride on.... ride on for a couple of minutes & then repeat the whole process a few times. 2 or 3 times is usually enough, and anything more than saaayy 5-6 times probably isn't going to improve things beyond what you will have already done. If it's still there after that, you can either ignore it or it's time to remove the pads & scuff them up to remove any glazing. Probably wouldn't hurt to use a very fine sand-paper to polish the discs too, but that's not usually recommended due to the risk of 'scratching' the disc rather than 'polishing' its surface.

[BajaRon]

That sort of 'brake pad rust mark' is usually caused by the vehicle been left sitting for a while without movement. It happens on pretty much every vehicle that sits for a few days; it starts to happen the moment you stop; and it will occur quicker if you've been riding/driving in the wet extensively but without any hard braking to heat up & boil off the moisture that accumulates in the pads thru use. It occurs because the tiny gap between the pads & the disc make for an ideal environment for mild surface 'rust' to start. It's normal, it's not usually damaging, and it's to be expected if your vehicle sits between uses, only most generally don't notice it because the 'discoloured patch' is hidden by the pads until you start moving again, and by then you're on/in the machine & the first few applications of the brakes will usually wear it off pdq!! If it's a bit more than what you get after a couple of days standing, it can make the brakes squeal a little until the pads/discs wear in again, and if it's really REALLY bad, it can require the removal of the pads & scuffing their surface with fine sandpaper.... but that's usually pretty rare.

However, if your vehicle has been left sitting for longer than a couple of days &/or left with wet pads in a humid environment. If it bothers you, just find yourself a clear straight stretch of road & when there's no traffic you can annoy or put at risk by doing so, take your Spyder's speed up to saaay 30-40 mph and (after checking behind to make sure it's safe) firmly apply the brakes so you slow rapidly down to about 10-15 mph then ride on.... ride on for a couple of minutes & then repeat the whole process a few times. Anything more than saaayy 5-6 times probably isn't going to improve things beyond what you will have already done.

Exactly right!

Disk brakes never actually 'Release' like drum brakes. They always maintain just a bit of 'Touch' with the rotors.

The best rotor material is cast iron. But cast iron rusts like a fiend! That's OK for rotors that are not seen. Like with solid wheeled cars. But for motorcycles... pretty ugly. So, they put a certain amount of nickle in, which helps resist rust. But nickle is softer than iron, more expensive, and also reduces stopping power. So they try to put as little nickle in as they can get away with and still end up with a relatively rust free rotor. But if you ride into your parking spot with hot rotors/pads, ride in wet, and then let your Spyder sit for an extended period of time. You're going to get these rust patterns which perfectly match the footprint of the brake pads.

Nothing to worry about. They will go away on their own after awhile. Faster if you follow Peter's advise.

[BLUEKNIGHT911]

Exactly right!

Disk brakes never actually 'Release' like drum brakes. They always maintain just a bit of 'Touch' with the rotors.

The best rotor material is cast iron. But cast iron rusts like a fiend! That's OK for rotors that are not seen. Like with solid wheeled cars. But for motorcycles... pretty ugly. So, they put a certain amount of nickle in, which helps resist rust. But nickle is softer than iron, more expensive, and also reduces stopping power. So they try to put as little nickle in as they can get away with and still end up with a relatively rust free rotor. But if you ride into your parking spot with hot rotors/pads, ride in wet, and then let your Spyder sit for an extended period of time. You're going to get these rust patterns which perfectly match the footprint of the brake pads.

Nothing to worry about. They will go away on their own after awhile. Faster if you follow Peter's advise.

with Peter & Ron and let me add - I think if the pads are wet from riding in the rain this more likely to happen ….. IMHO if you are parking the Spyder after a ride and it has been raining, I would drag the brakes ( lightly ) for the last 500 ft. or so to heat up the pad and the rotor.... this will help them to dry befaore parking …… Mike

[Raprider]

Thanks Peter and Ron and Mike!
I feel much better now

[missouriboy]

...rust patterns which perfectly match the footprint of the brake pads.

That was the first thing I noticed in the photos. So the explanations above were obvious to me...

[PinkRosePetal]

Your discs are a little unusual since the whole of the inside surface has rust on the rubbed area. Two questions; 1, are you using non-standard brake pads, and 2, do you wash your bike and then leave it with wet brake parts. I notice, also, corrosion on the wheel clamp surface and light rust forming on your wheel studs where the plating had corroded away.