Front brake lever free play

I wouldn't disagree, not entirely anyway. Pistons do get dirty so pumping them in and out helps remove clag that could otherwise cause jamming and piston corrosion. But yeah, the problem is when the seal grooves (which are bare ally) corrode, forcing the seals out and grabbing the pistons. In the worst case this means a dragging brake because the pistons don't retract, but it can cause excessive lever travel as the seals grab the piston and deform rather than letting it slide through.

Anyhoo, I've got a full set of seals coming in the post and I'll let you know how it goes. I love getting covered in hydraulic fluid and grovelling on the floor bleeding brakes

[Bibio]

bleeding brake is easy and the best thing you can do is take the bleed nipples out and put ptfe (plumbers tape) round the threads. hold the nipple part in your left hand and wind the tape over the top and away from you (clockwise) about 3-4 turns is enough. once the tape is on then roll the threaded part between your thumb and forefinger to 'crush down' the tape. dont put tape over the hole or conical at the bottom.

put a clear tube over the bleed nipple and the other end into a jar with some brake fluid in the jar so it covers the end of the tube then open the bleed nipple and start pumping, doing this there is no need to keep opening/closing the nipple on every stroke.

keep a bucket of water and a wet cloth handy for fluid spills. i also wrap a wet cloth round the MC.

top tip: use a dremel and a 'disc' wire brush to get the crud out of the seal recesses, i use a dab of autosol as well.

[Adam Ef]

I'd agree with a total strip down of the caliper and best to fit new seals if going to the effort to take it apart. The couple of times I've done it I've been amazed how much oxydisation needes scraping out of the recesses.

Top tip someone gave me was to get a sharp ended curved dental pick to really get into the recesses to scrape every trace of oxydisation out.

[ophic]

I used an old wooden kebab skewer

I've got a tool I made from an old tent peg, the end bent 90 degrees and ground square to fit in the grooves.

Anyhoo, the seals came so today I stripped and rebuilt the calipers. A couple of those pistons really didn't want to come out! Handy hint, take the calipers off the discs and pump the pistons out. Depending on the extent of wear of the pads the pistons should come "almost" the whole way out together without actually popping out of their bores. This makes the process of pulling them out with pliers wrapped in cloth much easier. No way could I have removed them if I hadn't pumped them most of the way out first. Surprisingly there wasn't much if any corrosion in the grooves, but 3 out of 4 dust seals were missing, presumably extruded and chewed up somewhere in the last 15 years. With a little clean-up, new seals and proper red rubber grease it all went in nice and easy. Cleaned up and regreased the sliding pins, half an hour to bleed it and the lever travel is definitely better. I suspect it'll improve again as the pads bed in. Roll on spring (yeah I'm an FWB ) Thanks all for the inputs!

[Adam Ef]

Originally Posted by Tomcatracing

..A couple of those pistons really didn't want to come out! Handy hint, take the calipers off the discs and pump the pistons out...

Or find someone with an air compressor to blow them out for you, making sure you stand clear while they do it!

Good to hear you got it sorted. Sounds like it needed it!

[Nutsinatin]

Originally Posted by Adam Ef

Or find someone with an air compressor to blow them out for you, making sure you stand clear while they do it!

Good to hear you got it sorted. Sounds like it needed it!

Leave an old pair of pads in, stops the pistons firing off! Gets the pistons past the oil seals and you can easily pull them out by hand at that point.