Brake rotor rust...

mn2007 · 01-28-2008, 11:49 PM

Hi,
Rainy season is here but I've only been caught a few times (and Im good about drying off the bike if it is drenched.) It's parked in the garage. I noticed today that all the rotors were starting to rust along the edges (not the surface.) The bike is less than 6 months old - Ive heard this corrosion problem with Ducatis but Im surprised - any suggestions? thanks,
m

RoLoo · RoLoo's Garage

...I polished the same kind of rust away with a bit of chrome-polish...
...rubbing it away with a (nylon) scouring pad will work also...

lee1980 · 01-29-2008, 02:44 AM

Theres some on mine around bolt heads not to much, bikes nearly 2 years old done 5300 miles by previous owner, and looks like not many wet miles either

phoenixtexoma · 01-29-2008, 05:24 AM

Although it's a lot of one-time work, you can remove the rotors and polish them carefully with something like Met-All. Use masking tape on the pad surface, and then spray high-temperature clear coat on them. I also had all my bolts, including the lug bolts, chrome plated (except for the threads, of course). Zinc plating would be ideal, but the rotors won't plate.

Bob Hancock · 01-29-2008, 05:32 AM

Might be acid rain or something because I regularly wash my bikes, dry them off, brief ride around the neighborhood, and back in the garage and I've never had anything like that....neither Ducati's nor BMW's.

JonyRR · 01-29-2008, 07:33 AM

I see you're in SF, no?

How close to the ocean are you?

that looks like saltwater corrosion to me...

Guest24 · 01-29-2008, 07:35 AM

Surface rust is a natural occurrence with ferrous materials. If left damp or wet it can develop in a very short time H-D went to chrome and stainless steel rotors to alleviate this problem but just plain steel or composite materials dissipate heat more efficiently which is a must for a sport bike. I use 00 steel wool to clean off the surface rust. I certainly wouldn't polish them.

BMathison · 05:00 AM

As Nail24 stated, it's ferrous iron and that is natural. The material was chosen mainly for it's friction properties (among a few other things) not corrosion.
Just use a little steel wool and don't fret it.

Even if you never took care to clean it, they would probably need replaced from normal wear before the corrosion ever got bad enough to worry about.

Edit: I was assuming they were iron, after looking again, I'm not sure they are.

Bob Hancock · 01-29-2008, 02:24 PM

Is this an R12S? I thought they were stainless. The rotors on my FE are iron and they will get a light rusting patina on them just from humidity that wears off quickly when used. Never seen it go out of the "braking zone", however.

JonyRR · 01-29-2008, 03:42 PM

Hmmm...I thought the R1100S OEM rotors were stainless. Mine sure seem like it. I have a meehanite iron rotor (from Kosman specalties) laying around and it surface-rusts like a bandit, but as Bob said, the pad scrubbing action when first engaged takes it right off.
Stainless in NOT rust PROOF, just very rust resistant, some more, some less, in it's various alloys. Moybin is a pretty darn good jackleg metallurgist, he could probably speak to this with great accuracy...

wswartzwel · 01-29-2008, 07:10 PM

Could be worn off bits of semi metallic material from the pads, rusting and leaving the stain.

Guest24 · 01-30-2008, 06:01 AM

+1 Jony. Stainless Steer does show surface corrosion. I've had stains where the moist pads touch showing the outline of the pads after a an overnight outside.

Fenring · 01:29 AM

I ride often in rain, and sometimes wash the bike too and leave it wet to dryout on it's own. It's normal for rust to form on the clear surface of rotors, especially under the break pads where water lingers, so these stainless steel rotors come as surprise to me. I've never seen rust form on the edges or near and around the bolts though. Could be salty air if you ride near the sea, or maybe you washed the bike with an over agressive detergent?

EDIT:
This morning I discovered similar rust stains on both brake rotors. The bike was outside over night, because i couldn't use the garage while the floor is being tiled. The night was cold, foggy and there was little rainfall as well, non directly on the bike, but enough to create a moist environment.

Bob Hancock · 01-30-2008, 01:11 PM

Quote:

Originally Posted by Fenring

or maybe you washed the bike with an over agressive detergent?

I've had S100 and the Honda stuff of the same formulation affect finish if not thoroughly rinsed off. Thorough as in wash it with soapy water and a mild detergent. Fenring may have something there.

plucky · 06-04-2009, 06:37 AM

I'm resurrecting an old thread for reassurance

I was out in the rain over the weekend and have rust similar to the photo in the original post.

I figure a nylon scrub pad would clean off most of it, but It seems to but under the mounting bolts as well - which concerns me more.

Will this grow significantly, or does it remain surface rust?

thanks

anotheroldrider · 06-04-2009, 08:25 AM

I can't see my rotors when I'm riding. I don't care when I'm not.

RBMann · 06-04-2009, 09:00 AM

I commute in Seattle all year round and never dry the bike=no rust. I am thinking if it sets outside the problem might be dog pee.

Moybin · 06-04-2009, 09:27 AM

2 cent opinion, nothing more...

Salt air in SFO can't be good. Like JonyRR says, there's no such thing as stainless steel, it's 'corrosion resistant' steel. That said, I'd be surprised to learn that the rotors were 'stainless'. Series 300 SS is high in nickel and won't temper or take an edge, so what we are looking at is not 300 series (look at the machining marks). I bet if you hold a magnet to the rotor it sticks. Only the 400 series SS will do that; no nickel just chrome and carbon, and that WILL tarnish. And magnets stick to non-stainless alloy steels all of which rust.

Then you have surface contamination in stainless steel, something called 'free iron'. If iron and/or low alloy steel particles get embedded into the surface, such as during manufacturing, and usually due to cross contamination from grinding and other metal working equipment, then the 'stainless' steel will start to corrode, very quickly, from the contamination sites.

Most of the bolts on the R11S series were carbon steel. Hence all the SS screw kits out there. BMW probably can't justify the cost of SS fasteners to the bean counters, so the R12S hardware is probably also carbon steel.

Bob Hancock · 06-04-2009, 09:56 AM

Quote:

Originally Posted by Moybin

Most of the bolts on the R11S series were carbon steel. Hence all the SS screw kits out there. BMW probably can't justify the cost of SS fasteners to the bean counters, so the R12S hardware is probably also carbon steel.

Made me look.

plucky · 06-04-2009, 10:27 AM

Quote:

Originally Posted by RBMann

I commute in Seattle all year round and never dry the bike=no rust. I am thinking if it sets outside the problem might be dog pee.

Not dog piss, Not salt water, just rain.

If I was concerned about looks, I would wash all the mud off the bike, too. I am concerned that if it gets worse, bolts will seize or I will have to prematurely replace parts. If it won;t get worse than pictured, than great.

They bike only has 2000 kms on it (800km mine) and it has been wet once (in the time I have had it), although it has been humid and cold, with condensation in my garage the last couple of weeks.