Just lining things up. am I wrong in thinking that loosening the mount, braking, and tightening the caliper up will in theory, centre it?
Juicy 3s if that makes a difference
i do that with mine and then 10 minutes later all i can hear is it rubbing again... which is why i've taken it apart and broken it
Ok, it's making more of a wsssssssss than a sh sh sh sh noise now. Something of an improvement at least.
technically, if your pistons exert exactly the same force and are free to return to sockets easily...yes
although manual alignment works best for me
when you have a good alignment, hold it firm and tighten BOTH bolts slightly then one all the way.
not all the way up one at a time
Never works completely for me. But it will get you nearly there, just have a slight wiggle and you'll get it.
Oh dear. Youve got juicy wschhh..
Anyway's what works for me is starting with the grab and tighten approach mentioned above. Then I get a torch, put that on the far side of the caliper, spin the wheel, squint to see where I can just see the light and see what side needs to move a bit as the rotor rotates. Id usually start with the side furthest away from me (I'd be at the front of the bike). Usually it's a tiny fraction to move. For me though there was usually a lazy piston, but I do ride in all sorts of conditions (you can google this).
I find it much much better to loosen the bolts, spin the wheel and tighten the bolts as the wheel spins. This also tells you if your rotors bent as you go from no drag (as the caliper moves with the bend) to drag when it's all fixed up.
If it's parrticularly stubborn I also just set it up by eye until I can see light either side of the rotor.
I find the loosen, brake, tighten method often results in drag and uneven pad wear.
I have two bikes, both with fairly large diameter rotors. I need these because I usually take a bike out to the Alps once a year. I've been using discs since '98 and have spent an inordinate amount of time experimenting with pads, alignment etc. Nothing seems to permanently fix these issues although my Hope M4s have behave very well for well over a year now.
I find two things apart from caliper alignment which contribute to this occasional irritating noise, which comes mostly from the rear rotor :
1) It happens a little going along in a straight line on road, but not offroad. I reckon this is due to vibration cuased by the knobbly tyres when ridden on hard tarmac.
Usually when going around bends, but is worse on road than off. I put this down to lateral play in my hubs and a bit of flex in the wheel. I have bog standard Shimano and Diatech hubs. The Diatechs make less racket than the Shimanos, but then the Shimano hubs are pretty worn and are entry level (M575s - no seal version of the Deore hub - not recommended!). I have adjusted the cones on both wheels, but these are as tight as they should be.
Smaller rotors would mitigate the problem. When I get a spare bit of cash, one of these bikes will get a full rebuild and i'll spec a much smaller rotor. This'll be my everyday UK bike as pretty much any rotor size will work in the relatively flat lands of the SE.
I have often wondered if the uber expensive Chris King hubs would solve my problem, but the ridiculous cost of buying and maintenaning thse puts me right off.