I am in the process of changing my rear brake  caliper and have adapted a R 1150 single sided caliper to fit the existing k100 FD. The only problem I have is the brake rotor just rubs on the top of the gap in the caliper. I would like to reduce the diam of the rotor by 5mm to allow clearance. Does anybody for see any dramas in doing this. To fill in the gaps the rear wheel is now a BMW hub laced to a 15 inch rim and the conventional caliper will not clear the spokes. Would I need any special tooling to trim the rotor down being stainless.

Provided the brakepads don't end up trying to grip either mid-air or the rotor centre, I don't see any problems with removing that much metal. You'll need a lathe and the proper cutting tools, but I'm assuming you already have those?

No kind of expert, but from my limited knowledge of machining, stainless is problematic. Someone will be sure to correct me if necessary, and I can ask an expert on Wednesday Oz time, but a sharp cutting tool and constant lubrication/cooling will be necessary, I think.

Bill

I'd agree with that Bill. I've drilled thru quite a bit of stainlees steel... very difficult. Need to use tungston carbide lathe bits at a slower speed. Spinning a disc with that diameter you'd need to calculate the required rpm.

And don't forget the earplugs. It's gonna ring like crazy!

Gold means low quality stainless it is the high chromium content that goes blue and nickel makes it gold then if hotter almost black

Ahhhh...... that might explain why every stainless brick rotor I have ever seen has brake pad grooves in it? I'm running cast iron rotors all round; I got incredibly lucky last week and got a second front pair off a breakers on ebay who were selling them cheap (£40) because 'they were covered in rust'. I said nothing and just hit the BIN button. Not a mark on them.

Glad it all worked out, Packo.

Bill