Much has been said over a number of years about the topic of cleaning bobbins and indeed the differences between semi and fully floating discs, in fact this topic has recently been discussed at length on another forum that I frequent, and it is from there that I have unashamedly stolen this video clip.......interesting methinks :yes:
https://www.youtube.com/watch?v=jJPCy2AsULo
A good video for demonstration purposes but having worked with race bikes on fully floating rotors I'd say his need replacing as they are worn well past their best. They should be noticably moving but not making excessive noise when the wheel is rotated, a slight click should be heard.
Most road bikes are now fully floating but are at much tighter tolerances than race bikes for 2 reasons, 1) they don't get as hot so require less room for expansion, 2) we want our discs to last as long as is reasonably possible. Race rotors typically need changing at the equivalent maximum of 6000 miles due to excessive wear on the centre boss as can be seen in the video.
I'm no engineer but even to my untrained eye and ear I thought that all was not looking or sounding well with that race bike example :no:
EDIT: what's your view about cleaning bobbins, should they be cleaned occasionally, regularly or left alone ?
Quote from: O.C. on January 22, 2018, 02:32:59 PM
I'm no engineer but even to my untrained eye and ear I thought that all was not looking or sounding well with that race bike example :no:
EDIT: what's your view about cleaning bobbins, should they be cleaned occasionally, regularly or left alone ?
I usually clean my bobbins when I service the brakes, pads out and clean everything, bobbins included with a toothbrush and brake cleaner, run the pistons out to more or less full travel first before cleaning. Once clean I apply a very light smear of red rubber grease to pistons prior to pushing back in. Bobbins are just cleaned and checked for free rotation.
I have the same opinion...preventative maintenance :yes:
Interesting, just cleaned mine, how freely should they rotate?
Quote from: GTRpilot on January 25, 2018, 01:01:01 PM
Interesting, just cleaned mine, how freely should they rotate?
They are usually quite tight and not that easily rotated, I put a short bolt through with a copper washer against each side of the bobbin, nip it all up tight and spray with brake cleaner and turn the bolt as you spray. You'll usually notice a slight difference once it is clean and rotating freely. Lack of free rotation can and usually does lead to warping of the rotors. Very unusual for rotors to warp if bobbins are free. :wink:
Quote from: Robbieben on January 25, 2018, 01:10:54 PM
They are usually quite tight and not that easily rotated, I put a short bolt through with a copper washer against each side of the bobbin, nip it all up tight and spray with brake cleaner and turn the bolt as you spray. You'll usually notice a slight difference once it is clean and rotating freely. Lack of free rotation can and usually does lead to warping of the rotors. Very unusual for rotors to warp if bobbins are free. :wink:
I'm told there are spring washers behind/between the rotor bobbins and that too much rotation can damage these washers. I do agree that letting them become very dirty/fouled can lead to warped discs long term
It's a topic that excites lots of opinion from those that 'do' and those that 'don't' clean bobbins.....I do clean mine but not too often