My RR7 failed its MOT due to "excessive binding of the front brakes". Hoping it might be a simple case of cleaning & lubing the pistons, I set about cleaning them up. However, one of the outer seals had seemingly failed and could be seen poking out of the bore! Obviously wedged between piston & bore, stopping the piston retracting, hence the binding. In for a penny, etc... I've removed and fully disassembled both calipers. Got new seal kit with bleed nipples from TRK incoming, along with slide pins from Pro-Bolt and even shiny new caliper joint bolts. Pistons themselves seem fine. Anyone got any words of advice or caution about rebuilding the calipers? I'm assuming it's simply a case of cleaning everything thoroughly, slather the new seals in red rubber grease, refit pistons, re-join the caliper halves, job done. Missed anything?!? Manky caliper, with manky joint bolt.
Brake fluid on the piston seals and red rubber grease on the dust seals, and only a smear. Also do not forget to service the discs, if the caliper was in that condition, when was the last time you cleaned and freed the disc bobbins? Seized bobbins, most common reason for warped discs.
Ah, important detail, thanks! With the bolt and washers so you can turn the bobbins? Haven't done for a little while, but you're right, I'll make sure I do that. Initial clean of calipers yielded ok results... think a bit more scrubbing is required to remove a bit more of the baked in brake dust. Shame about the pitting.
When I was commuting through the winter, it’s was a monthly PITA, just blast the bobbins with brake cleaner to soften up the crud and yes nut and bolt trick to grind out the crud and get them moving freely
You've pretty much nailed it. The bleeding process will be a PITA though. Don't forget to bleed the master cylinder too, otherwise you'll be there all day.
Do what I did, fit a set of 08 calipers - monoblock design (instead of split as on 07 and before) and straight swap, got a very clean pair for £80. If the pistons aren't pitted then the rebuild kit your using should solve things
Well this is a good option. If I had a bit more time I may have done this. I'd really like a set of brembo M4s, or even the new Hel ones... will have to wait until next year now.
Had another bash at cleaning them, but they're just not coming up great, so just cracked on. However, I like to thing the shiny new joint bolts, slide pins, and mounting bolts have made up for it. And look ok fitted Bled pretty well... now have the lever tied back (controversial?) to bleed the last bit of air out the m/c.
As usual I went overboard when servicing mine (a 2010) (same issue as you) Changed the pistons to SS (2008+ pistons will shockingly corrode) then polished them to 1micron Also bought and applied very small amounts snake oil lubes especially for pads/pins and clips - I know there is a lot of opinions/debate using any sort of lube in the brakes! Piston seals get brake fluid Dust seals get red grease Caliper gets a fine mist of ACF Bobbin maintenance For me tying down the lever ie keeping the system under pressure, is good check for leaks, allows full extraction of the pistons and allows the seals to reset (gives an impression of a hard lever), possibly compresses air bubble allowing them to reach the bleed nipples? Ongoing maintenance is none, I have found washing actually just washes all the good stuff away! Calipers just get a wipe down, bobbins get checked. The above gets repeated at each pad change
