caliper refurbishment

[thomas111]

Hi anyone on here refurbing calipers one of my pistons is only moving a wee bit the other 3 moving ok

[Wicky]

Blow or pump em out to check seals, condition of piston and clean em up or replace. Plenty of threads on the subject if you search using keywords.

[thomas111]

Thanks wicky the piston in question is not moving out enough to try pull it

[Dr B1G]

Search YouTube for tutorials, it's easier than you think

[Wicky]

Thanks wicky the piston in question is not moving out enough to try pull it

Block/clamp the moving ones with spacers and pump / blow the stubborn one out. Might want to wear eye protection/bullet proof vest when carrying this procedure out.

[BrianC]

I can only reinforce to be very careful with blowing a piston out. I used my mini compressor to try and dislodge the piston in the rear calliper and very stupidly put my thumb between the piston and calliper side and basically trapped my thumb nail !!!!!!

Picture me running round in agony trying to get something to prise the piston off!!!!

Some humour but it bloody hurts!!'!!! And it leaves you with a black nail

[sirch345]

If you remove the pads, unbolt the caliper from the fork leg and keep the brake hose connected. Find yourself a piece of metal about 4mm thick by around 25mm wide and the same length as the caliper or slightly longer, cover it in a piece of cloth to protect the pistons, drop it in the groove in the caliper centre, groove pointed out in photo below with red arrows. The metal will then hold the pistons from coming all the way out so that more pressure can be put on the sticking piston(s) (you'll need to hold it in place with one hand while you operate the brake lever with the other hand). Once you get the sticking piston(s) moving you should be able to clean it/them. Once clean, push it/them back in a little and pump it/them back out, doing that a few times should free it/them up.

NOTE keep an eye on the fluid level, you will most likely need to add some with the pistons coming out this far. Also once the pistons are all free you may need to syphon some fluid out of the master cylinder reservoir before you can push all the pistons back into the caliper. I would cover the fuel tank and fairing as much as you can before starting the job, just in case you should get any brake fluid splashes. Brake fluid will damage your paint if you didn't already know.


My photo is just for reference to show the centre groove I'm talking about, ignore where the pistons are, although you can pump them out until they touch in the centre of the caliper without losing any fluid.



Anyone thinking about working on brakes, only do so if you feel confident enough.

Chris.

[thomas111]

Thanks guys job done

[Wicky]

I can only reinforce to be very careful with blowing a piston out. I used my mini compressor to try and dislodge the piston in the rear calliper and very stupidly put my thumb between the piston and calliper side and basically trapped my thumb nail !!!!!!

Picture me running round in agony trying to get something to prise the piston off!!!!

Some humour but it bloody hurts!!'!!! And it leaves you with a black nail

LOL Get a candle and straighten up a paperclip - I'll let you work out the rest on how to release the pressure under the nail as a very charming grinning nurse did many moons ago in A&E after my first ever bike crash involving a Ford Capri coming out the wrongway from a one-way street into my path.

[BrianC]

I passed on that method - happened a few weeks ago so i just put up with it lol

You live and learn !!!!

[thunderbolt]

I can only reinforce to be very careful with blowing a piston out. I used my mini compressor to try and dislodge the piston in the rear calliper and very stupidly put my thumb between the piston and calliper side and basically trapped my thumb nail !!!!!!

Picture me running round in agony trying to get something to prise the piston off!!!!

Some humour but it bloody hurts!!'!!! And it leaves you with a black nail

PICTURES please!!!

[kev64]

Brake cleaner is your friend doing this job

[thomas111]

Thanks kev yea I used the brake cleaner and did you get they links I put up for you for the bellypan in ur post in the wanted section

[agentpineapple]

I refurbed two rear calipers, I used the mini compressor method, the first one came out nice and slowly, but the second one shot out so fast, it flew across the room, narrowly missing a window and hitting a wall, it would have easily smashed the window....
note to self, be careful next time......
I hope the fingers feeling better mate, I've smashed my thumb 3 times, twice needing hospital treatment, so I feels ya pain.

[MacV2]

A grease gun.

With the caliper off pump grease in via the bleed nipple.

It's a bit messy but it works, you just need to make sure you clean the caliper really well afterwards with lashings of brake cleaner to get all the grease out.