removing brake pistons.

[red_phil]

Hi all.

I recently scored a GS500 front brake caliper on e-bay.
It's in a pretty good state, but I was wanting to replace the oil and dust seals.
problem is, HOW do I get the pistons out to remove the old seals?

Currently my old Caliper is still on the bike and functioning but it sticks a bit.
I planned on reconditioning the new one then doing the swap in one go so
my bike wouldn't be off the road long. For this reason I would like to avoid
connecting the new caiper up to the bike just to shift the pistons.

oh, and I dont have an air compressor.

Any good ideas?

[onefastgs500]

phil take caliper off take to somewhere that has air use a rubber tipped blowgun place a rag where pads go and blow with air(keep fingers out of the way)

[3imo]

wouldn't it be possible to just remove the pads and pump the brakes until the pistons came out?  just an Idea.

[sledge]

A bycycle hand pump is the best way, but you need to come up with a way of connecting the the pump to the caliper inlet. I used a combination of brake line, hoses and jubilee clips. You can feel when the piston is just about to `pop` out. The rubber tipped high pressue method works but you have little control. Removing the pads and pumping the lever is a recipe for disaster.......you will dump all the brake fluid  over the calper, fork leg and wheel.

[gsmetal]

Take it to a garage and have them blow it out.

[Turd Ferguson]

Indeed, I'd just take it somewhere.  If they try to charge you, leave!  It takes 2 seconds to remove with a rubber tipped air gun.  Put something soft on the pad cradle so the piston doesn't hit it and cause damage.

-Turd.

[red_phil]

Thanks for the Advice.
Done now.

tools used.
1 Towel (fluffy)
1 foot pump
1 G clamp


I put the banjo bolt & connector from my new Stainless brake line onto the caliper, then rammed the foot pump adapter onto the end of this.

the connector looks like the bottom item in this picture


It was a bit tight but the thread helped screw the pump on.
Next I put the towl in place to catch the pistons and pumped.

*POP!* larger piston comes out.

Then I placed the large piston just a little bit in and used the G calmp to hold it there.
Another pump and *pop* the smaller piston is out.
Now the big piston is almost out and I  pulled it free with my fingers.