Not sure if its classed as a piston so here goes. I have just minted the bike and decided to remove the front brake calipers and to clean the pads ect. The pistons were in the half open state except for one out of the four so i carefully pumped the lever to slightly open them so i could clean around them but only three worked so i pushed them in and tried again (3 times) each time one then the other came out except one .Whilst arseing about one then popped out just! ( and there was a very small loss of brake fluid Doh! .So Two questions here.(1) How do i get the stuck one out or will it work when all back together (2) Will the fluid loss put air into the system. ?
any loss of fluid is a bad sign. I'd remove the calliper completely and strip it for a full clean and replace the seals. You need to have a reasonable idea of what your doing with it.
Yes mate i'll need bleeding up again which is only a 2 minute job though. While they're off, seeing as you also have this issue wit one piston, get them all out, clean them up and service the calipers, it's satisfying and well worth it!
Not on a bike but had this on my car a couple of weeks ago. As said complete take out and strip down. Put the freed pistons in and secure them G clamp, block of wood? Then use an air line to blow the frozen one out. Make sure it can't come out completely, because depending on the pressure it goes like stink. If need be you can always use a pair of mole grips, just make sure you only clamp them on the very edge so as not to damage where the seal fits. Good clean up with scotch pad, re grease new seals and away you go..
The worry i have is that this bike is ABS and noting previous threads i thought it was a 3 hour job in the bike shop (Might need a little more help soon.Ta!)
I think i may have sorted without bleeding .I freed the piston off using a piece of cut plastic to hold the opposite pistons apart and an hex key between the 3rd piston and the inner caliper body so after a good dose of good old WD 40 and the other 3 pistons jammed i operated the brake lever and it came free so i cleaned around it did it again for luck and got it working ! So i sprayed the pads with brake cleaner and whilst wet give them a good rub with course sandpaper and a few more sprays loads of black dust came off them dried everything up and give it a run. So without a bleed the brakes feel a bit better with no brake lever issues or the like. (Have i got away with it??)
I stripped mine down last night. The calipers do not really have good dust seals around the pistons which lead to brake pad dust gathering around the piston which gradually corrodes the surface. Race spec pads are the worse than road pads as they throw off more abrassive dust. The pistons are made of alloy so rust is not a problem but it is wise to clean them every now and then with good quality brake cleaner, and if you want to push the boat out then remove the pads and wind the pistons in to clean the inner bore area.
O dear you defo defo defo need to bleed the brakes mate!!! and its ABS so enjoy! You should get away with a simple full bleed at each front caliper ie open nipple with a pipe on it into a bottle thats got flud in ie pipe in fluid then pump half way at a time!! repat till no air comes out and and gazza airline on a bike caliper and Boom fire lol not lke a car man
When you ride, check the discs occasionally, not after heavy braking, to see if one is hotter than the others. If consistently hot, remove all pistons,clean n polish em, check or replace seals and when rebuilding smear seals with Red Rubber grease. Usually works for me.
Cheers for the help boys .Just to be safe i took it to a mates and he checked it over and bled it . He said there was a tiny amount of air so thats that .Just come back and yes rode in the wet (Boring) I have just put a tie wrap around the lever as suggested so that may help although i am 100% .I have cleaned and put new pads on various bikes and in the past bled a couple of bikes but it seemed to take for ever due to me being a bit over critical and keep doing each side just in case and that as you know will go on forever.So minted today and the sucker is filthy again! having said that although it was only 20mins of a ride i really lapped it up'' good pace'' (except the roundabouts) taken about 5mph.
