07-22-2019, 02:27 PM
As Ohiorider says, have a shop check the runout on the discs with a dial indicator. Only need to check the outside surfaces, no need to check both sides. This is common practice on car brakes, and could show only one disc is out of true. Absolutely no reason to replace both if one is good.
Back in the late-'70s early-'80s Suzuki and Honda big bike rotors would warp from hard use, and replacements were no better. We used to have a machine shop surface grind them, and they wouldn't distort again. I would rather pay to have them surface-ground than try new ones. There is a saying that a new part is an untested part.
More complete machine shops will have them - similar to a milling machine, but a grinding wheel is used instead of a rotating bit, and the surface is much smoother and more precise. The process is to grind the mounting surface first, the outer surface next, then the inner surface.
(A shop I used to work at had one, and they would also grind valve shims if they didn't have the right size)
I can't think of any reason short of impact that a rotor(or rotors) can get bent in normal use. I've seen discs galled and blued that were still straight.
If you had the wheels painted or powdercoated, the disc mating surface needs to be masked as well as the bolt holes.
Back in the late-'70s early-'80s Suzuki and Honda big bike rotors would warp from hard use, and replacements were no better. We used to have a machine shop surface grind them, and they wouldn't distort again. I would rather pay to have them surface-ground than try new ones. There is a saying that a new part is an untested part.
More complete machine shops will have them - similar to a milling machine, but a grinding wheel is used instead of a rotating bit, and the surface is much smoother and more precise. The process is to grind the mounting surface first, the outer surface next, then the inner surface.
(A shop I used to work at had one, and they would also grind valve shims if they didn't have the right size)
I can't think of any reason short of impact that a rotor(or rotors) can get bent in normal use. I've seen discs galled and blued that were still straight.
If you had the wheels painted or powdercoated, the disc mating surface needs to be masked as well as the bolt holes.