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Brake piston removal tip


Steve Blackdog

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Steve Blackdog

I thought I should share the very easy (if not potentially dangerous) method I used to remove the piston from my rear brake calliper. Not sure this would work for multiple pistons, but with the rear single pot, it does the trick.  
 

Honda say you should used compressed air - squirting bursts of air to push out the pot. 
 

I don’t have an air compressor.  But I do have a soda-stream CO2 bottle….  I use it to top up my beer pressure barrel.   It has a “hambleton bard” style adapter:-

 

https://www.co2supermarket.co.uk/sodastream-hambleton-bard-s30-homebrew-p498.html
 

Simply place a tap washer over the brake fluid inlet and give it a short burst of CO2. 
 

WARNING:

 

the piston will fly out, so you need to place the calliper on a solid surface (work bench), with the piston facing away from you, preferably wrapped in a cloth to prevent damage to the piston. Note that CO2 powered air guns are potentially lethal.  I would expect a flying piston would do a serious injury. 

 

 

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outrunner

If you do not have access to air/co2 pressure then put the caliper still connected to the pipe in a plastic bag and use the brake pedal/lever to push it out then disconnect the pipe. Makes the caliper messy but you are going to clean it anyway. :D

 

 

Andy.

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fusing a piston tool is way the best option unless very badly sizes then reconnecting to the hydrolicsbleeding and usindfluidpressure is the correct option using ANY gas is dangeriousas gas incompressible and a sudden freeing can No Will resultin a flying piston

In the workshop we have spare master cylinders and hoses so it simple

again donot use compressible medium   i.e. any gas !

 

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Christmas 2020 I bought my son a pair of Draper Expert Motorcycle Brake Piston Pliers from Machine Mart. He always had problems removing brake calliper pistons. He reckons it is one of the best tools that he has in his tool kit and saves time, causes no damage to the piston or calliper and is safe to use. I have no connection with Machine Mart apart from being a very satisfied customer.

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Steve Blackdog
13 hours ago, davebike said:

fusing a piston tool is way the best option unless very badly sizes then reconnecting to the hydrolicsbleeding and usindfluidpressure is the correct option using ANY gas is dangeriousas gas incompressible and a sudden freeing can No Will resultin a flying piston

In the workshop we have spare master cylinders and hoses so it simple

again donot use compressible medium   i.e. any gas !

 

As I said it flew out.  Like all things being aware of the danger helps, but it probably isn’t worth the risk. 
 

I encourage anyone tempted to use CO2 to free a piston, should read Dave’s post and find a safe way to do it instead. 
 

so how do you use piston pliers- there’s virtually nothing to get hold of?

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outrunner

Piston pliers fit inside the piston, then open up to press against the inside giving you a grip on the piston.

Like these.

 

Andy.

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Beerbelly

I managed to use a foot pump over the bleed nipple on an old Yamaha caliper, bit faffy to get a good seal but it did the trick.

Edited by Beerbelly
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Johnnie Mototrans

No excuse if the correct tool is less than £20.

However.

I have successfully used expanding rawl bolts for the job.

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Andy m

I've always used the master cylinder and bucket method. Wear rubber gloves of course. 

 

I've never seen any huge risk with compressed air, but then again it's what I work with. It will deliver a lot of energy of energy though and if you release it you can expect projectile motion*. Use a regulator and point it somewhere safe. 

 

*Off topic commercial vehicles park on spring brakes. You usually have a 24 square inch piston that pushes a spring back at 4 bar or so. Release the air and the spring puts the brakes on that'll hold 5 tons on a 40% gradient. The spring is made of wire as thick as your thumb and uncompressed is a foot long. There are clear warnings not to remove them from the casing, the factory uses a remote hydraulic press inside a box made of three inch thick steel. The MOD decided this didn't apply to them and took an angle grinder to one. The back half of the case and spring went through a breeze block and brick wall and embedded itself in armco across the width of a road. The weapons test could be viewed as unsuccessful as the REME failed to do more than worry the cavalry regiment they accidentally were pointing it at. 

 

Andy 

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Steve Blackdog
3 hours ago, Johnnie Mototrans said:

No excuse if the correct tool is less than £20.

However.

I have successfully used expanding rawl bolts for the job.

According to Honda the “correct” tool is an air compressor!

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