brake rotor grooves

kz750 ltd 1980 has 3 brake rotors and all of them have grooves/scratches I am not sure if they are supposed to be that way.
They are cross drilled for heat dispersion and I am wondering if I should take them down. I tried my belt sander on the back rotor with the center stand and the wheel spinning with no real results.
I have to get another set of pads for the front.
Should I take the old metal from the bad pads all the way around to flatten the rotors?

They're stainless steel. belt grinder won't do a lot.

The minimum thickness is cast into the rotor, so measure them and figure out if they'll still be thick enough after turning/grinding, the if they are then look around for a machine shop with a Blanchard grinder.

Or measure the diameter (four cylinder I assume) and post it and I'll see if I have any.

Its been that way for a long time, and so evenly, I am wondering if they were made that way.

donthaveakawman wrote: kz750 ltd 1980 has 3 brake rotors and all of them have grooves/scratches I am not sure if they are supposed to be that way.

Not when new, but all rotors develop grooves with use. It depends how deep they are. If you can hang a fingernail in them, that's too deep.

donthaveakawman wrote: They are cross drilled for heat dispersion and I am wondering if I should take them down. I tried my belt sander on the back rotor with the center stand and the wheel spinning with no real results.
I have to get another set of pads for the front.
Should I take the old metal from the bad pads all the way around to flatten the rotors?

I went to Harbor Freight and got a small rectangular sharpening stone and used machine oil and worked the rotor faces gradually (rubbing the stone diagonally across the grooves). Takes a really long time, go slow and do both sides. It took a couple of hours, use calipers to monitor thickness but you probably could only take off a couple of thou in an hour if that much.

steell wrote: They're stainless steel. belt grinder won't do a lot.

The minimum thickness is cast into the rotor, so measure them and figure out if they'll still be thick enough after turning/grinding, the if they are then look around for a machine shop with a Blanchard grinder.

There are a couple of places online that grind them, but you can't "turn" them like regular rotors they have to be surface ground like a flywheel. A shop that can do flywheels might be able to do them.

www.thumbtack.com/mi/carleton/motorcycle...-old-rotors-like-new

www.truedisk.net/

here's a blanchard grind service:

www.aptechservicesinc.com/machine.htm

edit error - my mistake

bountyhunter wrote: There are a couple of places online that grind them, but you can't "turn" them like regular rotors they have to be surface ground like a flywheel.

You can turn them on a lathe, just make a stub shaft to bolt them to that fits in the chuck, then make a two tine tool holder with a tool bit in each tine so you can cut both sides at once, and have at it. Not economically feasible for a commercial shop at the moment, but certainly the guys with lathes in their garage can do it. I'm not sure they couldn't be turned on a regular brake lathe. Can't think of any reason they couldn't be.

bountyhunter wrote:

steell wrote: They're stainless steel. belt grinder won't do a lot.

The minimum thickness is cast into the rotor, so measure them and figure out if they'll still be thick enough after turning/grinding, the if they are then look around for a machine shop with a Blanchard grinder.

There are a couple of places online that grind them, but you can't "turn" them like regular rotors they have to be surface ground like a flywheel. A shop that can do flywheels might be able to do them.

www.thumbtack.com/mi/carleton/motorcycle...-old-rotors-like-new

www.truedisk.net/

here's a blanchard grind service:

www.aptechservicesinc.com/machine.htm

Thats what I do,just take them to an auto parts store that oes flkywheels,just make sure they have enough meat left to machine the grooves out

martin_csr wrote: Afterwards, should he look into getting different brake pads having a softer metal? To prevent regrooving the disks?

They're ebc brakes, I don't think there are any hooks underneath the pads, the metal is soft enough to slow me down. :evil:

martin_csr wrote: Afterwards, should he look into getting different brake pads having a softer material? To prevent regrooving the disks?

Problem is that now that asbestos is illegal, newer pads are a lot harder. Most are either metallic or semi metallic. They do seem to eat rotors more than the ones we used 25 years ago.