Disc Rotor Vibrations

[Brett CT]

I have recently upgraded my rear disc rotors from 160mm to 180mm and almost from the beginning of the swop I have been experiencing vibrations when applying the brakes. Today was the day to tackle the issue  and I initially thought that I might have a bent rotor but when I checked the rotor seems to run true. The rotor and pads are new and I haven't had any significant crashes since the swop.

Upon closer inspection of the rotors there is wear below the main ring of the rotor, onto the arms that support it and the about a 2mm section of rotor that does not show wear on the outer edge. It looks to me like this could be causing the vibrations as the support arms pass between the brake pads.

Has anyone else had this issue before? Can I solve it by spacing out the calipers so that the pads are better positioned? I have a set of convex/concave washers that I saved from a previous set of brakes that look like they will work well to solve the issue.

I just thought to check if someone may have come across a similar issue before.

 

[Newbie321]

Did you get the correct adapter when going from 160 to 180?  https://bike.shimano.com/en-EU/service-upgradeparts/mtb/category/disc-brake-mount-adapter.html

[guidodg]

I would add 2 thin washers to raise the caliper a little so the pads run more central to the braking surface...

[Steady Spin]

I have a 203mm rotor on 200mm adapter on the front and spaced it with 3 flat washers. No issues at all. 

You can safely space it. 

[thebob]

Did you change the pad compound or brand with the new pads? If I was you I’d give the disc braking surface a clean with brake cleaner then a light sanding with some high grit sandpaper and then another clean with brake cleaner. Also hit the pads with the sand paper and clean with brake cleaner. After than bed the pads in properly and hopefully the vibes will be a thing of the past

[RobertWhitehead]

You can add some spacers no worries. What I find a bit interesting is that the caliper actually drops in that deep without catching the roof of the caliper. Normally I know to add a spacer if it catches the top and makes a hitting sound. But if you need some more of those spacers you're welcome to look me up. I do have one or two. 

[HowardSteele]

If all else fails...Switch on and off 😊A friend of mine had a shudder on his disks after coming back from the LBS...after trying every thing we removed the disks...cleaned re-seated the disk tightening the screws like you would a car wheel ..every second bolt in rotation. worked like a charm .

[MORNE]

22 hours ago, HowardSteele said:

If all else fails...Switch on and off 😊A friend of mine had a shudder on his disks after coming back from the LBS...after trying every thing we removed the disks...cleaned re-seated the disk tightening the screws like you would a car wheel ..every second bolt in rotation. worked like a charm .

Underrated comment.

if you aren't drawing imaginary ‘pentagrams’ while tightening an array of bolts you should not even be doing something that basic in the first place. This can 100% cause a wobble. And then you don't fix 1 down all the way before moving to 2 and the rest. Snug…then rinse repeat. If you use a torque wrench you’ll know the difference this makes.
 

Edited May 1, 2022 by MORNE

[dasilvarsa]

That Disk Look a little Contaminated.