I too have had a spongy brake lever and have bled the brakes to death trying to fix it. The lever firms up nicey but not what I would call 100% as it just lacks that initial bite. The brakes work nice (new pads just fitted & caliper rebuild with new pistons & seals) but they just lack the initial bite they had when I first had the bike. I know it could be the master cylinder but when working on the bike today I noticed a drop of fluid or two under the reservoir where it meets the master. It could have dripped down from the res if it got past the baffle but it didnt look that way and if it is the o-rings it would explain the spongy lever. If I bleed from the top it does normally have a few bubbles instantly and the lever feels a tiny bit firmer but this doesnt last very long. I have read posts about the reservoirs letting in tiny amounts of air and replacing them but rather than shelling out on something I am not sure will cure the problem, I am hoping to simply change the O-rings and see what happens. So, has anyone else done this and what sort of O ring can I use with brake fluid? Can I use some of these if they are the correct diameter?? Halfords | Halfords Assorted O-rings Large Whoops... should have been in Technical help.....
