Sprint Fractures In Rear Disc Sprint Rs, Anyone Seen This?

Hi all,

T'other week I bought another Sprint RS (MOT failure) as a donor for spares for my own. It is a 24,000 miler and failed on weeping fork seals (MOT tester specified as 'fine misting of oil on both forks) and a rear disc with multiple fractures. I have inspected the rear disc myself and it does indeed to have numerous small fractures that sprout off the holes drilled in the disc. Has anyone seen this on discs and, if so, any idea what causes it? I wouldn't fancy the idea of a brake disc disintegrating at speed!

The bike is actually so nice that I am contemplating storing her and tidying her up (the pillion section of the saddle has been horribly brutalised and there are a few stickers in odd places including a bleeding Shoei sticker on the centre of the nose cone flanked by some pointless(?) holes) with a view to then using her next year and doing up my current Black one.

 

I'd never heard of it before and, if I hadn't been looking for it I wouldn't have seen it. I seem to recall reading once of a brake disc disintegrating many many years ago but would I be right in assuming that it's not that common for a disc to actually go terminal? The guy that sold me the bike seemed to be of the opinion that the MOT tester had been a little picky in regard of the disc and the fork seals.