What is this on my disc brake caliper?

s1mples

I was just realigning my disc brakes on a new to me MTB which are 2011 XT. There is what almost looks like a clip but feels like a ratchet when tightening!?

Cheers in anticipation.

whyamihere

It's to stop the bolt loosening. You're supposed to take it off when adjusting the bolts, then put it on when they're torqued to spec.

s1mples

Good job I asked then:-)

Thanks I'll take another look.

JBA

Shimano call it a 'stop ring'.
Spread the open ends apart slightly and you can remove it then refit it once you have retightened the bolt.
They are usually fitted to the calliper bolts rather than the adapter bolts.

reaperactual

Is it just me that's never seen them on adaptor bolts then?

Trying to look closely at the pics, as far as I can make out they don't look like the prongs are 'locked' to anything and are ineffective in stopping those bolts rotating anyway.🤔

JBA

reaperactual said:

Is it just me that's never seen them on adaptor bolts then?

No. As I said in my post, they are usually on the calliper bolts. However, Shimano fitting instructions do show them fitted to IS adapter bolts.



They don't 'lock' on to anything. Rather one or both of the prongs will butt up against a surface and prevent the bolt from rotating.

s1mples

Thanks for the further info.

reaperactual

Lock, wrong wording, butt up, more descriptive, either way I just throw them in the bin, use thread locker and tighten the bolts to 8Nm. Never had a bolt come loose yet.