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Can anyone help me with information on how to get a stuck brake piston out to clean an lube it?It's the rear caliper I'm trying to rebuild, When I got this aspencade last month, it was in alot of parts and pieces - the brakes being someof them, so I can't use the brake pedal to pump them out.and I'm sure they have alot of "crud" stuck down with the pistons, they are both (both pistons) really seized up, Is there a way to get the whole caliper apart or is there something a repair shop can do to maybe press them out? Or should I just bite the bullet, give up with this one,and try and find another caliper.Thanks to all who contribute here, I'm learning alot about this great motorcycle.:cool:
 

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Compressed air.

Calipers off the bike, just stick an air hose blow gun in the brake line hole and the piston should come right out, maybe forceably, be carefull, place a shop rag around the piston and caliper to slow the parts and stop the fluid from becomming airborne.
 

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Another method is to hold on piston in place with a c clamp and press the pedal to push the other piston out some, then alternate back and forth until both pistons are almost all the way out, then you should be able to get both out.
 

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If you're planning on replacing the pistons (and if stuck that badly they probably need replacing) and can't get them out with brake pressure and air, try grabbing them by the exposed skirts with a pair of pliers and rotating them while using air or brake pressure. A penetrating oil will help, but make sure you flush out the caliper with brake fluid when cleaning them.
 

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 Pliers will damage a piston for sure !!!...... If you want to keep the piston, and  try to clean it up./forums/images/emoticons/big_grin.gif........... I once   removed   pistons  undamaged  with the brake pressure,  and a  narrow strap wrench/forums/images/emoticons/cool.gif... clean the exposed  piston wall, and rub a little cleaner  on the inside of the strap, to soften it up just a bit... (makes it tacky/forums/images/emoticons/confused.gif )... .  rotate the piston with the wrench as you push with the brake  lever.... as I recall, I clamped the other piston with  a C-clamp... and took them both out in stages  until they freed up../forums/images/emoticons/big_grin.gif........  SilverDave /forums/images/emoticons/emoticonsxtra/cooldj.gif
 

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SilverDave wrote:
Pliers will damage a piston for sure !!!...... If you want to keep the piston, and try to clean it up./forums/images/emoticons/big_grin.gif........... I once removed pistons undamaged with the brake pressure, and a narrow strap wrench/forums/images/emoticons/cool.gif... clean the exposed piston wall, and rub a little cleaner on the inside of the strap, to soften it up just a bit... (makes it tacky/forums/images/emoticons/confused.gif )... . rotate the piston with the wrench as you push with the brake lever.... as I recall, I clamped the other piston with a C-clamp... and took them both out in stages until they freed up../forums/images/emoticons/big_grin.gif........SilverDave/forums/images/emoticons/emoticonsxtra/cooldj.gif
Yes pliers may damage the piston, however with a little care they won't, I've done it more than once on frozen pistons. It's a bit academic anyway, it the piston is stuck that hard, it's likely to be pretty well corroded and need replacement. I don't think it's a good idea to buff down a piston so much as to remove the plating. If the pitting is such that it's necessary to sand it down that much it would be better to replace.
 

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Max 5640 wrote:
Can anyone help me with information on how to get a stuck brake piston out to clean an lube it?It's the rear caliper I'm trying to rebuild, When I got this aspencade last month, it was in alot of parts and pieces - the brakes being someof them, so I can't use the brake pedal to pump them out.and I'm sure they have alot of "crud" stuck down with the pistons, they are both (both pistons) really seized up, Is there a way to get the whole caliper apart or is there something a repair shop can do to maybe press them out? Or should I just bite the bullet, give up with this one,and try and find another caliper.Thanks to all who contribute here, I'm learning alot about this great motorcycle.:cool:
Max 5640, with the master cylinder being in parts & pieces you have lost the option of hydraulicking the pistons out with the bikes brake system..

Other choices include placing a hard piece of wood in the caliper opening (between the pistons & caliper) then using compressed air to blow the piston(s) out.. If doing that do so away from any painted things like cars, trucks, bikes, etc.. Sometimes when they pop out it will blow some brake fluid around.. Be sure to add the wood (or plastic) between the pistons & caliper so the piston(s) don't come blasting out & damage them. Also be sure to keep your finger out from between the pistons & caliper as they could severely damage your fingers..

If you don't have high pressure compressed air, or that doesn't work, then find a threaded brass pipe bushing that comes close to fitting the brake hose hole on your caliper, theninstall that bushing, then install a grease Zerk fitting in the bushing,, then use a pump up grease gun to force the pistons out.. If one starts moving let it move a little then place a wood block between the piston & caliper to keep it from popping out, then allow the other piston to also move.. If those pistons are stubborn you might have to use a propane torch to heat the caliper slightly while applying grease pressure.. You will be surprised at how much pressure a grease gun can generate..

Twisty
 

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Modern hand operated grease guns can deliver 6000 PSIG of force, so be careful and be cautious, since when excessive pressure is used any part prone to failure, the likely hood of failurewill do just that, safety glasses and coverings over the caliperare needed. High pressure hydraulic fluids can pierce the skin and cause all kinds of medical problems, grease, brake fluids are under great pressures, but the use of a hand operated grease gun is even higher.
 

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I know a guy that has a non running bike just sitting there to hook calipers up to the hydraulics to force out the pistons. Really. Wierd, eh? Maybe you can bolt the rear caliper up to one of the front hoses if you're also going to be messing with the front. Verify same size banjos first. Bob
 

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Whether you use compressed air, the bike's brake system, pumped grease or whatever, wrap the caliper in a rag first so the various crud, fluid and whatever that flies out will be trapped.
 

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don't hold the caliper in your hand. loss of fingers type scenario, put the caliper in a cardboard box with some rags and a piece of wood between the pistons and the caliper. I use air, you go to your nearest gasstation and ask them to pop them for you also.
 

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I used a pair of nylon jawed plumbers pliers to gently twist the pistons back and forth until they loosened up. Then I alternately pumped them out using the brake pedal/lever and increasingly smaller sockets to brace the one while the other pumps out.

Hobie
 
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