www.zxrworld.co.uk

Noted. All good advice as usual.

Cheers for all the tips/advice.

Corosion can build up in the groove that the piston seals sit in the caliper. This causes the pistons to stick
The only really effective way to fix this is to remove the pistons and seals.
I use a small rotary wire brush with my Dremmel that just fits nicely in the groove and cleans them out till they shine

If you managed not to damage the seals thay can be cleaned in water (NOT solvent of any kind) and reused but it's better to fit new ones (dead cheap anyway)

Getting the pistons out can be done useing the brake lever and the hydralics but you need to ease them out together as once one is out then the fluid is gone............and then you'll need a compressor...........or a garage airline.

I'll see how I get on cleaning the 5mm of piston that was suggested, before taking
the whole lot apart. Failing that a full piston removal/clean is on the cards. Dremmel
is on stand-by.

Might have inadvertently used some spirit to clean all the gunge/salt etc off
the calipers. Could that have had a go at the seals? Seeing as how you've
said only to use water near the seals?

If its a water based spirit then it should be ok. You should use a can of brake cleaner anyway.

Getting a feeling that it'll not be a quick clean up job after all.
Think I used bog standard white spirit, not sure if that's water based or not.
May even have thrown some meths on as well to try and shift the crap, so
looks like I've dived in head first again.....

cargo wrote:Corosion can build up in the groove that the piston seals sit in the caliper. This causes the pistons to stick

never thought of that cheers! next time Gems pistons stick i'll look at that.

well, personally id go get some brake cleaner and carry on. If its gotten worse then you know they are now ruined and time to start stripping. for the tough bits a use a flat tipped screwdriver to shift them off, just dont press too hard.

Just nipped out and got some brake cleaner and rubber grease. Guy behind the counter
can't have been wearing his mask, cos he just charged me £1.50 for a sachet of grease!

I'll keep on the cleaning route and see how I get on. No point in taking the whole lot apart
to find the seals are ok after all.

Not looking forward to completely stripping the brakes down, given the increased opportunities
for me to break something
Also, one of the pins that go through the pads is completely jammed in the blind hole. No
amount of coaxing/wd40/etc could shift it, so the new pads had to be fitted by splitting the
caliper.

bit of heat and a lot of wriggling should shift them pins.

On all of my bikes, ive dabbed the end of the pin in copper grease so it never gets stuck again!

Funnily enough, I was worried about the rubber seals when I was applying the heat.
Didn't give them a 2nd thought when dousing liberally with every chemical in the
shed!!!
Didn't go in too hard when trying to shift that pin, for fear of breaking it altogether.
The one on the back brake was stuck too.

Put a wee drop of high temp grease (only stuff I had) on the end of the pin that I did
manage to get out for the future.

Good stuff, any grease should do i guess, long as it prevents the corrosion between the pin and the caliper

Tried cleaning and greasing the pistons, but they're not going anywhere
quickly. One of them caam out easy enough using the brake lever, but
is a bugger to go back in, so it looks as if the seals will need replacing.

One question though, do the pistons on the outside of the caliper travel
further than the ones in the inside? The outside ones seem to be doing
most of the moving.

cheers