Is this rotor bad? Is it fixable?

[jwess1234]

First ride today--got the rotors as a demo that only had a few miles. Front had discoloration, but I thought nothing of it. Until I went for my first ride today on my new bike, when the rear was super grabby and responsive (easy to lock up rear if I wanted). The front was not powerful at all and not responsive/grabby.

Here it is...

I only did about 3 miles to test the bike and the pads are all brand new. Is this contaminated with something, is it salvageable? Thanks in advance!

[11.4]

Did you bed the pads according to directions? That could explain the braking action.

I don't see anything on the rotors that suggests they are toast, but clean them carefully with isopropyl alcohol, wipe as well with acetone just to be sure, to be sure you got off any trace lubricants that are contaminating your pads. That this is happening on the rear always makes me ask about contamination. You'd probably be mentioning raucous noise if the pads were contaminated with oil, and I don't see lines from any solid material contaminating the pads.

I don't see marks suggesting that the rotor is bent, which potentially could be an issue.

Clean the rotors first, bed the brakes properly, and see if that fixes it. You may have to ride it for a bit to get rid of any surface irregularities on the rotors. And are the pads sintered or fiber? You get more noise and less smoothness with sintered pads.

Try that for starters. You'll get plenty of more comments here by the time you've done the basics.

[CiclistiCliff]

Scuff up the rotor with 80-100 wet dry paper. 'Resurface' the pads as well. Grab a bottle of water and squirt it at the caliper and hold the brake as you ride it around the block to heat up rotor. It's going to squeel until the water is gone and pads bed in. Boom. Silence. Good to go.

Lastly, looks like you may have some spacers between the caliper and mount. Remove them as the pads are not fully contacting the rotor.

[miguel]

80-100? **** no. Like 250-600. You just have to take the top layer off and that's not much

[lzuk]

You might try laying the rotor on a flat surface. Wrap 220 grit around a small block of wood. sand a bit angled and across the rotor face and wipe with a solvent.

[peanutgallery]

Hold the sand paper, Nelly

What you have is shimano. Clean everything with dawn and rinse. Pads, rotors the works. Reinstall

Splash a little water on there and ride. Grab the brakes and they bed in. Works every time

You roadies are going to have to step up your game with disc:)

[jwess1234]

Thank you everyone! Going to try to do this today--and yes, I need to step my disc game up!

[unterhausen]

Shimano apparently has a new brake pad formulation that doesn't suck as bad. I mean squeal as bad.

[Ken Robb]

Or you could upgrade to the lighter, well-proven, trouble-free dual pivot calipers. :D

[jwess1234]

Here's what I did and it worked:

Sand rotors with 220 wet/dry paper
Clean rotors with a fresh cloth and iso alcohol
Clean rotors with acetone
Sand pads with slightly coarser paper
Clean pads with iso alochol
Clean pads with acetone
Bed in by going down hill and doing moderate and consistent braking in various lengths of time, not locking up, not stopping completely


Made a world of difference at the end of the bedding in--much more responsive and grabby. No squealing sound at higher pressures like before. You can see the difference in color, so I presume the guy I got the rotors from had a slight contamination. You can see remnants of that color in the second pic towards the top on the edge of the cutout.

Thank you again everyone for the help!

[Joxster]

Simple fix

1: fit caliper/cantis
2: toe in blocks
3: ride bike

[oldpotatoe]

Or you could upgrade to the lighter, well-proven, trouble-free dual pivot calipers. :D

You mean those disc brakes with 622mm rotors and rubber compound disc brake pads with single point, flush mount hardware???:)

[Ken Robb]

You mean those disc brakes with 622mm rotors and rubber compound disc brake pads with single point, flush mount hardware???:)

You could put it that way, I guess. Wonderful marketing. :banana:

[CiclistiCliff]

80-100? **** no. Like 250-600. You just have to take the top layer off and that's not much

Ummmm, you need to scuff it to remove whatever pad material off and give it a coarse ish surface for new pads to bed into.