disc marks

[butthead]

hopefully ive uploaded a picture of my front disc, it looks initially like watermarks but its not , im not sure what it is hence why im posting to gain your thoughts , best theory so far is its age related marks on one disc only but both sides of that disc and only the central holes and marks are clearly centrifugal in nature  , braking is as powerful as always no drop of in performance and there is nothing to feel ,cant detect any deformation , i actually mostly removed the marks with 400 wet n dry took it for an hours spin, in the dry, the marks are back again following that. bike has only done 32k miles and im not a heavy breaker by nature but i didnt have the bike from new but it only had 16 k when i got it so ive done half of those miles , theres no splits or cracking around any of the holes so there not stress marks , but what the cause is i cant figure?

[agricola]

Discounting chemical reaction, water marks etc, I'm leaning towards hairline cracks at the surface. Reason I say that is because the rotor looks to have its fair share of wear judging by the steps at the outer and inner edges, with the deepest scores across the affected holes. As rotors wear, the characteristics of the metal can subtly alter due to constant heating/cooling/chemicals on the road etc and this can show up on the surface as hairline cracks a few microns deep. I'd check the rotor thickness against the minimum spec first and if on the limit or below, then new rotors first up

[butthead]

Discounting chemical reaction, water marks etc, I'm leaning towards hairline cracks at the surface. Reason I say that is because the rotor looks to have its fair share of wear judging by the steps at the outer and inner edges, with the deepest scores across the affected holes. As rotors wear, the characteristics of the metal can subtly alter due to constant heating/cooling/chemicals on the road etc and this can show up on the surface as hairline cracks a few microns deep. I'd check the rotor thickness against the minimum spec first and if on the limit or below, then new rotors first up

i cant see any hairline cracks not without checking with a magnifying glass ,which now i will check deeper as i do have a magnifying glass but i did search online about this very topic you suggest and the hairline cracks are very visible to the naked eye but they might have been extreme examples ? , but it could be that these marks are the precursor to hairline cracks ?  you are correct , the discs are fairly worn and are near the wear limit,  i dont know what mileage you'd expect to get out of discs but id imagine way more than the 32 k its done .

[BBROWN1664]

If they are near the limit, scrap them anyway.

[returning rider]

What pads does it have? sintered pads can increase disc wear quite a bit no idea how long you should get out of them as everyone brakes differently.

If they are near the limit then I would replace them

is the other disc worn to the same level? strange this only happens on one disc

[butthead]

What pads does it have? sintered pads can increase disc wear quite a bit no idea how long you should get out of them as everyone brakes differently.

If they are near the limit then I would replace them

is the other disc worn to the same level? strange this only happens on one disc

they are sintered pads yes , i believe the discs are the same age and both show similar amounts of wear but these marks are only on the one discs , both sides of that one disc.

[Grahamm]

Are the marks smooth, or do you feel a dip when you run your finger over them?

It could be that the disc is starting to warp.

[butthead]

Are the marks smooth, or do you feel a dip when you run your finger over them?

It could be that the disc is starting to warp.

no theres no dip or any deformation completely smooth to the touch.

[unfazed]

If it's the left disc then marks are most likely cleaning fluid marks after being on the side stand . They are probably on the inside of the right hand disc and nothing to worry. Just check the thickness of the disc as others have said and replace them if necessary. I use EBC Sintered pads and never had any issue with them wearing the discs just great brakes. My discs lasted too 70,000 miles and that included track days and city riding to and from work

[returning rider]

If it's the left disc then marks are most likely cleaning fluid marks after being on the side stand . They are probably on the inside of the right hand disc and nothing to worry. Just check the thickness of the disc as others have said and replace them if necessary. I use EBC Sintered pads and never had any issue with them wearing the discs just great brakes. My discs lasted too 70,000 miles and that included track days and city riding to and from work


Good to know sintered are the better option but on cars at lest they do increase disc wear but at 70k no one can grumble that awesome my bike will never see that many miles 

[unfazed]

If it's the left disc then marks are most likely cleaning fluid marks after being on the side stand . They are probably on the inside of the right hand disc and nothing to worry. Just check the thickness of the disc as others have said and replace them if necessary. I use EBC Sintered pads and never had any issue with them wearing the discs just great brakes. My discs lasted too 70,000 miles and that included track days and city riding to and from work


Good to know sintered are the better option but on cars at lest they do increase disc wear but at 70k no one can grumble that awesome my bike will never see that many miles 

I noticed that they do increase disc wear in Cars. I dont think the Car Discs are as hard as bike ones. I bought Brembo vented front discs for my car last time and they were a fifth of the the price of the Brembos I bought for the Fazer.

[darrsi]

I had an issue 2 years ago with rapid disc wear after i tried a new set of SBS pads on the front.
Please note that i do have aftermarket discs, due to another issue many years ago, but my normal pads that i'm always going on about for the front are Galfer G-1054 and they have always not only lasted a long time but were extremely kind to the discs showing barely any wear at all. They were so good i just presumed that sort of thing was standard, but when i had a go at the SBS they ate the discs and i had to remove them after 6 months, bought Galfer again, then things went back to normal.
On that note i presume SBS are okay on OEM discs so bear that in mind too, but i personally haven't tried that combo.
Always Galfer on the front for me, but i do buy Ceramic SBS for the rear as they do keep the dust down and treat the disc pretty well.

As mentioned though, if any of the discs look ropey you might want to start saving to purchase a new pair, or if you're lucky you may even find a decent used pair if you search around. Otherwise after market ones will be the cheaper option by far. Unfortunately brake discs and rear shocks tend to be the pricier parts on these bikes, but for most people brakes and tyres need to be in tip top condition because nothing else will stop you, not in a pleasant way anyway.

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What pads does it have? sintered pads can increase disc wear quite a bit no idea how long you should get out of them as everyone brakes differently.

If they are near the limit then I would replace them

is the other disc worn to the same level? strange this only happens on one disc

Depends how well you look after your calipers and pads really? The pads, calipers and discs are independent on each side, so they don't always have to behave the same way.
For starters, something no doubt overlooked by many is simply keeping the pad pins clean so that the pads can slide freely without getting stuck in place which can lead to all sorts of unwanted grief.
And better still, you can pull the pins out while everything else, including the pads, can remain in place.
I use stainless steel wool to clean them up very quickly, the type you use to scrub pots and pans with, and because the pins are so accessible this can be done a few times a year and takes less than ten minutes to do. The rear pad pins just need unscrewing and can be done as well while you're at it.
It's really worth learning how to clean the calipers up yourself as well, which i tend to do at least once or twice a year, normally before and after winter as i ride all year round. 
Once you've finished the brakes will feel like new and become extremely sensitive and powerful, which is when you realise how grubby they can get.