Help: 85 ATC250R removing piston from brake galiper

[Sinbad46]

Hi, someone have a solution for me. I want to remove the piston from front and rear brake galiper to replace the seal and dust seal...how can i push out theses piston?

[WIkid500]

AIR. I messed with mine on my X and the best way is to take the line off and put the blow gun to it. Give it a few nice shots of air and it will pop out. Just keep your hands out of the caliper while your doing this it WILL pop out with some force, it there isn't a better solution.

[Twilight]

I put duct tape over mine so they would hit and stick to the tape when blowing air.

[WIkid500]

I put duct tape over mine so they would hit and stick to the tape when blowing air.

Heh I just learned another trick. Thanks. :beer

[Sinbad46]

did you seal the gun with the oil inlet for doing that...or put the gun like 1 inch of the hole?

[WIkid500]

If you have a blow gun with a rubber tip you are good to go. I just used a rag in and around the tip and shoved it all in the hole and held the button till she popped.

[DIGGER DOG]

you could of course if you dont have air and the seals dont leak bad is keep the calipers assembled on the bike and pump the levers that works if you have single piston calipers and no air your just using the brake fluid to pump piston out.
I use air.

[Sinbad46]

ok thanks, i'll try that!!

[DeePa]

usually on dual piston calipers, one piston will come out first, then the other. well if one comes out, you lose pressure, and you have to put a piston back in.

I use a c clamp to keep one piston just close enough to hold pressure, so then the other piston starts to come out. Once the second one is one, i can usually wiggle the first one out by hand.

[Dirtcrasher]

I crack the bleeder and put a grease gun on it and remove them hydraulicly. Sometimes air doesn't do the trick, hydraulics have more force than air does......

[Sinbad46]

and after that...you clean the grease from the galiper? You remove all the grease successfully?

[WIkid500]

Use brake clean and emery cloth. It's a caliper BTW. When you put the piston back in get yourself some Syl-glide It's like an o-ring grease that will help you get the piston back in without ripping the new seals.

[Sinbad46]

with grease gun....piston are out in 10 minutes :) thanks!!!
The front piston are in plastic and the rear in steel....if the piston have some scratch on it...does replace it for new one or just sanding with fine sanding paper?

[WIkid500]

Mine had one deep gouge in it. I filed the ridge off and took emery cloth to it. Doesn't leak and it works good. Just hit it with some fine sand paper and polish it up.

I like the grease gun Idea too.