Right, I think I need to rebuild the brakes on my 4s. The lever pressure is good, but the effort doesn't seem to translate to stopping power as well as it used to. I know you generally have to go via KTM to get caliper seal kits, but do you have to do the same for the master cylinder kits? Anyone have the spec of the seals from KTM? P
I've no experience with ST4S or KTM, but I'd be surprised if the master cylinder had problems if you get good lever pressure. For calipers it could be worth doing the easier job of giving them a really good clean before resorting to rebuild. The first thing to do is to whip them off and have a good look to see if one or more pistons is staying in when you squeeze the lever.
@Recidivist Yeah, I've done that fairly regularly, cleaning up the exposed piston area and surrounds and then using red rubber grease on them, and there has been an improvement each time, but the bike has now done just 54k miles and I think there might just be wear on the seals. I changed the brake fluid recently too and after a good bleed, it felt good initially but there just doesn't seem to be a the same initial bite as before. A
Good point - that's a significant mileage! There could also be a build-up of dirt/corrosion in the grooves in the caliper where the seals fit, perhaps making the tighter/stickier.
You would think so but when I did mine at 30K+ the pistons and bores were like new. Maybe one seal had gone but the others were also in very good condition
@johnny: That's a fair point mate, but 54k is a lot more than 30 and while I wpould generally do a good clean and lube every spring and autumn, I wouldn't be meticulous in between. A
