Shimano disc brake C bolt

joeyhalloran
Posts: 1,080
in Workshop
I am fitting Shimano flat mount disc calipers (grx) to a new frame and the existing bolt is now too long.
Does anyone know what the advantage of Shimano's C bolt is? It looks like it fits some sort of retaining clip but that part is buried deep inside the caliper. What does it do that a normal M5 bolt doesn't?

Does anyone know what the advantage of Shimano's C bolt is? It looks like it fits some sort of retaining clip but that part is buried deep inside the caliper. What does it do that a normal M5 bolt doesn't?

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Comments
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On my GRX calipers there is an opening on the "back" for installing the bolt fixing pin.
See page 22 here:
https://si.shimano.com/pdfs/dm/DM-GADBR01-01-ENG.pdf
On the front bolt, as you say, it's not fixed with the pin and a normal bolt would do.
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ah, I hadn't noticed that! Thank you.
Now, I wonder if that pin is really needed? Or just Shimano making super double sure.0