hi all
I noticed this anomaly on saturday, I'd just got a new M.O.T . when I noticed this strange marking on my front disc.
The history of the bike ,is that it stood idle for fifteen years in a lock-up surrounded by paint products, thinners etc after the cam shaft crapped out and the poor soul who owned it previously had a leg off
When I started to renovate the bike back in the late nineties,I had to turn off all the old chrome plating as it had started to lift and the brakes would have been either totally ineffective or downright dangerous.
The radial drillings I done myself using a dividing head on a mill,in the vain hope of improving the front brake and dispersing any water (still as wooden as ever)
The problem is this looks like a hairline crack forming , you can feel it with a finger nail, but only in one direction and its no where near my drillings and not noticable from the other side, Has anyone else ever seen such markings on their discs
steve
Attachments imag084.-jpg.jpgHi Steve, I have seen this…
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As you know, the standard…
As you know, the standard brake is rubbish. Now's a good time to junk the original set-up and fit a brake that works. I'm not a massive fan of RGM but I've had their master cylinder conversion for 45,000 miles without problems. Fitted a Lockheed racing caliper same time.
This year, I fitted a pukka Norvil disc from Mick Hemmings to replace the rattly RGM product. Braking hard from any speed is a two fingered operation.
If you go down this route you'll then have to improve the fork compression bump stop. Brakes are one of the many things not worth taking chances with - unless you enjoy hospitals.
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Hi Steve,
I have seen this before, it is heat cracking in the surface. It is not usually a problem. The fact that it doesn't come from a hole or edge means it won't get to the point of failure. Just keep an eye on it and check it doesn't grow.
if you are really concerned you can get it crack tested using magnetic partical inspection. Google it and you will see how it's done. They will be able to do it with the disc on the bike and shouldn't cost to much. A good inspector would have seen this type of cracking and can advise you.
good luck. D