SOHC.co.uk Forums > CB350/400
Drilling brake rotor
Mikep328:
I have a spare CB 400 front brake rotor and am thinking about having it drilled. I COULD do it myself but the measuring/marking out/drilling the holes is more fiddly than I prefer to deal with! ;) Can someone recommend a UK shop that does this?
DomP:
If you have a pillar drill I'd go with plan A, I found print out templates for my xs disk online. Low speed/cutting oil and go up through drill sizes stating at around 3mm and its easy, centre punch all holes first for a nice accurate start.
Mikep328:
I decided that, although it looks cool, drilling the rotor was too much trouble/effort for what is just an "appearance" thing. I can spend more "bike time" doing more useful work! Today I'll be checking out the clutch and neutral switch mentioned in a different thread.
TrickyMicky:
--- Quote from: Mikep328 on August 06, 2025, 08:30:25 AM ---I decided that, although it looks cool, drilling the rotor was too much trouble/effort for what is just an "appearance" thing. I can spend more "bike time" doing more useful work! Today I'll be checking out the clutch and neutral switch mentioned in a different thread.
--- End quote ---
I agree with you wholeheartedly re the "appearance" thing. The idea of drilling holes into a possibly 50 year old brake disc beggars belief. The invisible damage that could be caused to the metallic structure of the disc doesn't bear thinking about. A shattered brake disc is a frightening prospect. I think with the choice of pads available now, the old problem of wet weather braking has been all but eliminated. The number of holes I have seen in some discs must have surely reduced the amount of braking surface area, and as for "cooling", we are talking about vintage vehicles on public roads, what sort of riding is required to get the brakes that hot? Maybe we should start drilling through the rear brake drums as well. Good luck with the clutch switch, a solution to a much more everyday problem. Stay safe.
ST1100:
https://4into1.com/ sell drilled SS repros of the P/N 45120-374-700 rotors...
https://4into1.com/stainless-steel-drilled-brake-rotor-honda-cb450k-72-74-cb500-550/?searchid=3556121&search_query=45120-374-700
seem the safer option over DIY drilling... but I don't know about about import VAT and/or other trouble arising in the strange times we currently live in...
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