seized pistons in caliper

[1foggy]

Hi all took the calipers of the bike today to change discs and in both calipers the pistons that run on the outer side of the disc dont move and are flat to the bottom of the caliper any ideas on how to get them out to clean them so i can get them working again cheers

i thought of doing to get a screw driver on the in side of the piston to push it around to free it what do u think
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900 blade RR wpb yx160

[nsr_J22_FOXEYE]

its been done before, and it works but be careful it you put the pad in first as the are quite malleable.
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Never Ride Faster Than Your Angel Can Fly

[1foggy]

[Ichy]

Connecting an airline can help but be aware that if they are seized and it takes a bit of air pressure to release them then they piston can launch itself with a hell of a lot of force.

The easiest way by far is to leave it connected to the brake hose, clamp up the moving piston to stop it moving and then apply pressure at the lever. Keep pumping.
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https://www.metacafe.com/watch/1972097/how_to_behave_on_a_forum/

[dna50]

some people suggest put compressed air into the piston and they pop out but depends how bad they are. on my bike they were badly seized i had to use a parrafin heat gun on the back off the piston and then let it cool then sprayed wd40 in the gap after it had expanded and cooled. but yours should pop out if there not that bad with an airline if not compressed air
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hsaeed

[Scotsman37]

Or a tool like this will help you do the job without scratching the hell out of your pistons

https://www.pvrdirect.co.uk/productinfo.aspx?catref=VS1806

https://www.pvrdirect.co.uk/netalogue/photos/Sealey/VS1806.jpg

[BanditsHigh]

As mentioned above, the easiest and safest method is to connect them back up and use the brake system to get the pistons out ... easy, no damage to pistons and you don't kill yourself (or anyone else) with a piston being flung across the room.

On twin sided calipers I usually put a spanner down the length of the caliper and then pump the brake lever until all the pistons hit the spanner ... on single sided calipers I pump one piston out and then hold it with a G-clamp and pump the other out ... once they are mostly out it's quite easy to remove them.

The reason your pistons are seized is due to corrosion building up at the back of the dust seal groove, this jams the seal against the piston stopping the piston retracting when the brake lever is released ... clean corrosion out and then refit seals and piston (replacing with new items when required).

Have fun

[serlant]

[cyberglass]

this is what i do but with a spanner wrapped in a rag to stop any damage to the piston.
https://www.youtube.com/watch?v=mE-qitXDbuM
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DL650 Vstrom 2004
DRZ400S 2003
Yamaha R1 2005

[1foggy]

sorted it thanks to alex h it was just the dust seals that were holding the pistons back just glad its done
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900 blade RR wpb yx160