Seized caliper pistons - going nuts!!

[GrumpyGuts]

Hi,

I've spent all day trying to get these bastards out:

https://i46.tinypic.com/352kyvc.jpg

But I'm about to give up. I used a G clamp to push them down so I could break the seal that was keeping them frozen, then force them out with compressed air. That idea didn't work as too much air was leaking around the nozzle...so I hooked up the calipers (front calipers btw) and tried to use hydraulic pressure. No dice, the fluid was being forced back into the MS.

I'm totally stuck, literally. This caliper was bought off ebay to replace the caliper that had the snapped bleed nipple!

Anybody got any ideas?
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My Bikes: Lifan Beat 125cc '11 -> Suzuki B120P '76 -> Suzuki EN 125-2A '08 -> Honda CG 125 '04 -> Honda CB600F Hornet '98 -> Kawasaki ZZR 600 '99 -> Kawasaki GPZ 500S '95 (Current)
Theory test passed - 09/02/2012 >>>> Module 1 passed 24/07/2012 >>>> Module 2 passed 24/10/2012

[Pigeon]

Would a release agent be of use on this? Doubtful.

What about hot+cold?

Apply some heat to the outer casing and dump a few ice cubes inside the pistons.

Still needs the compressed air to work though.

I have no idea what I'm talking about though.

[SWID]

Connect them back up to the MC & use hydraulic to push them out.

Don't be too eager, calm down, relax & be patient !

I find it hard, very hard to believe that you've already done this & fluid was being forced back into the MC.

[mr jamez]

You can buy rubber tips to go on the air blower. I think I've got some elctrical tape wrapped around the end of mine for this job as its tapered. Does the trick, with a loud pop
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NSR 125F > BROS 400 > NC30 > BROS 400 > Trumpet S4 > '97 VFR 750

[Pete.]

Clean the caliper first to make sure none of that crud gets in the hole the pistons come out of.

Fill the master cylinder, remove the pipe banjo at the master cylinder and pump the level with your finger over the hole to prime the piston. Try not to spray fluid all over the paintwork. Now quickly fit up the brake line and do the same by pinching over the banjo at the pipe end. Hook the caliper back up to the brake line and bleed it normally.

Now put a flat bar/spanner across the gap where the disc runs in the caliper and pump out both pistons until they both touch the bar. Clean both pistons with rag wetted with brake fluid, press them back in a ways and pump them out again. Whichever moves the easiest, try to hold that back with something and pump the other one all the way out with the bar removed, then pull out the other piston.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[GrumpyGuts]

In the meantime what can i soak the caliper in to help loosen it up?
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My Bikes: Lifan Beat 125cc '11 -> Suzuki B120P '76 -> Suzuki EN 125-2A '08 -> Honda CG 125 '04 -> Honda CB600F Hornet '98 -> Kawasaki ZZR 600 '99 -> Kawasaki GPZ 500S '95 (Current)
Theory test passed - 09/02/2012 >>>> Module 1 passed 24/07/2012 >>>> Module 2 passed 24/10/2012

[SWID]

[Kickstart]

Hi

Suspect nothing you soak it in will help, and some things will hinder (anything that reacts with the seals and makes them expand). Normal problem is a build up of corrosion between the seals and the caliper.

Fully agree with Pete on bleeding them through and carefully pumping the pistons out.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[GrumpyGuts]

Would it be easier to use the brake hose from my CG to connect it to the MC on the Hornet and then the other end on the caliper?

It's a pain in the arse pumping fluid into two calipers - so in effect all the pressure will go into one caliper as these pistons are frozen solid? (dust deals were actually wedging the piston)
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My Bikes: Lifan Beat 125cc '11 -> Suzuki B120P '76 -> Suzuki EN 125-2A '08 -> Honda CG 125 '04 -> Honda CB600F Hornet '98 -> Kawasaki ZZR 600 '99 -> Kawasaki GPZ 500S '95 (Current)
Theory test passed - 09/02/2012 >>>> Module 1 passed 24/07/2012 >>>> Module 2 passed 24/10/2012

[Kickstart]

Hi

Yes, pretty much any hose and master cylinder will do it. Short hose probably makes it easier. You don't even need to use brake fluid, and water would do the job fine (not like you are using the brakes like that so no heat for the water to cause a problem, and you will have cleaned out any trace of the water when you clean the calipers up)

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[GrumpyGuts]

Thanks for the advice lads...

OK to use water? (Sorry I am still learning) I'm running out of brake fluid and have no new copper washers left!

When I tried to use hydraulic pressure before, it was extremely difficult and I was not getting anywhere, however I shall try again.

Thanks again and I will let you know what happens!
____________________
My Bikes: Lifan Beat 125cc '11 -> Suzuki B120P '76 -> Suzuki EN 125-2A '08 -> Honda CG 125 '04 -> Honda CB600F Hornet '98 -> Kawasaki ZZR 600 '99 -> Kawasaki GPZ 500S '95 (Current)
Theory test passed - 09/02/2012 >>>> Module 1 passed 24/07/2012 >>>> Module 2 passed 24/10/2012

[Kickstart]

Hi

For THIS it is fine. Just make sure there is no water in the caliper / hose / master cylinder after you have cleaned everything up and are reassembling it.

At this stage all you need is something that will transfer pressure and water is just as capable of doing that as brake fluid.

Where water causes problems in brakes is that it boils at a relatively low temperature compared to brake fluid. Hence as braking from speed is converting forward motion to heat you don't want water in the brakes in normal use.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Triumph1300]

DON'T use water.

1 drop left behind in a hose or whatever will cause problems.

Just get some cheap brake fluid
____________________
BWJ
Back on a BMW R80RT
Punctuation - the difference between knowing your shit, and knowing you're shit

[SWID]

I cannot frickin believe that folks are advising someone to use water in a motorcycle braking system.

What's next? WD40 to clean brake dust off pads, sillicon spray to shine up tyre treads

[dansp1]

[Kickstart]

Hi

The water is irrelevant. It isn't going to contaminate the system (ie, using a spare hose), and if you clean the calipers out you will likely use far more dodgy stuff. The water isn't going to react with the hoses, seals or anything else, and unlike brake fluid it isn't going to strip paint off things it gets onto (important consideration when you are using it to pump out the piston when fluid will inevitably pee out all over the place)

You aren't using the water as brake fluid, merely a temp fluid to push the pistons out. Then you are stripping and rebuilding the caliper, cleaning out and flushing out any debris. Then thoroughly drying it of any residue, whether that is water, brake fluid, brake cleaner or anything else.

And yes I have done this quite a few times. Prior to putting the caliper body under the tap and cleaning with the water and then drying it thoroughly (air line).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[GrumpyGuts]

I'm borrowing the hose from the CG so not really a spare, but to be honest that needs new fluid anyway. I can stick the air compressor nozzle down the pipe and flush it before I bleed that caliper.
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My Bikes: Lifan Beat 125cc '11 -> Suzuki B120P '76 -> Suzuki EN 125-2A '08 -> Honda CG 125 '04 -> Honda CB600F Hornet '98 -> Kawasaki ZZR 600 '99 -> Kawasaki GPZ 500S '95 (Current)
Theory test passed - 09/02/2012 >>>> Module 1 passed 24/07/2012 >>>> Module 2 passed 24/10/2012

[SWID]

The very real prospect of even a minute amount of water remaining in the system is enuff to not even go there.

Please DO NOT under any circumstances EVER put water in a motorcycle's hydraulic braking system.

Kickstart knows no better. This bloke/twat once claimed that drilling a hole in a bar makes it stronger

[mospeed]

Send em back to the person on ebay, if youve been trying this long to get the pistons out with no joy.

[Kickstart]

[SWID]

[Old Git Racing]

You'll be ok using water as a temporary fluid to get pistons out, done it many times myself, just flush it through properly after. As said recycle the real fluid.

OGR
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2022 Tiger Sport 660 2019 Street Twin 2003 K3 gixxer 1000 1998 Srad 600 track hack

[carvell]

[Kickstart]

[SWID]