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Classic Bike Trackdays

SDR200 front brake conversion
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James P



Joined: 31 Mar 2013
Posts: 184
Location: Sydney, Australia

PostPosted: Mon Jun 22, 2015 2:32 am    Post subject: Reply with quote

arlurt wrote:
...Of course your new calliper bracket can't just be in flat plate can it? The one you have looks like it's milled away where it mounts to the fork leg, and I guess it's also cut away on the face that the calliper mounts to?


Yes, that's right - the SP Tadao adaptor in the photo gives the caliper zero offset; i.e. the caliper is in the same position (relative to the centreline of the bike) as it would be if simply bolted to the fork leg with no adaptor. It is made from 13mm plate, milled to half thickness on each side. My new adaptor will be of similar configuration.

I suppose I could have used the 1KT disc and made a different adaptor for the caliper (with 5.5mm offset), but the disc was still too close to the fork leg for my liking!
I don't anticipate any further problems, but will post an update when I (eventually) get it sorted.

Regards,
James
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James P



Joined: 31 Mar 2013
Posts: 184
Location: Sydney, Australia

PostPosted: Fri Aug 21, 2015 2:08 am    Post subject: Reply with quote

I've made a bit of progress on this:


This is the semi-finished adaptor, based on the SP Tadao design.


I didn't have any suitable material to make the new adaptor and neither did my machinist, so I had to buy some. Making a rough measurement of the cardboard template suggested that 80x16 flat bar would be suitable. Unfortunately, when marking out the profile, the template overhung the edge of the bar, but only by a millimetre or so. Even more unfortunately, I made a mistake in allowing the overhang to exist on the "visible" part of the adaptor, rather than the part which would be hidden behind the fork leg...doh! Embarassed That is why the radius around the top rear caliper mounting hole doesn't look right. I only realised the impact of the error halfway through the milling process. I may or may not decide to tidy it up later - I'll live with it for the time being.


Luckily, the basic design seems to work, as the brake pads align with the disc's braking surface properly - no "wasted" pad surface now. The new adaptor is 16mm thick, compared to the 13mm of the SP Tadao adaptor. I'm of the opinion that any minor weight advantage would not justify the work involved in milling the new adaptor on both sides to reduce the thickness.

Regards,
James
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arlurt
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Joined: 28 Nov 2006
Posts: 680
Location: North Yorkshire

PostPosted: Fri Aug 21, 2015 6:56 am    Post subject: Reply with quote

Looks good.

Why not just reduce the radius round the calliper mounting holes? Looks like you've got plenty of material there to do what it needs to.

I'd think you could take material out of one side of the bracket as well, to make it more "C" shaped than square. the stuff in the middle isn't adding any strength where you need it. That would make it lighter, and perhaps less obvious as an adapter plate.

If you made it a backwards "C" you could keep the material where it's so nicely shaped round the fork leg mount and reduce the radius at the calliper mounts at the same time?
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James P



Joined: 31 Mar 2013
Posts: 184
Location: Sydney, Australia

PostPosted: Sat Sep 05, 2015 8:31 am    Post subject: Reply with quote

arlurt wrote:
Looks good.

Why not just reduce the radius round the calliper mounting holes? Looks like you've got plenty of material there to do what it needs to.

I'd think you could take material out of one side of the bracket as well, to make it more "C" shaped than square. the stuff in the middle isn't adding any strength where you need it. That would make it lighter, and perhaps less obvious as an adapter plate.

If you made it a backwards "C" you could keep the material where it's so nicely shaped round the fork leg mount and reduce the radius at the calliper mounts at the same time?


Good advice! I have deliberately left it alone for the time being, so I can have a think about the best way to tidy it up. If I don't make a hash of it, I'll put up a picture of the outcome Laughing .

Regards,
James
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