Author Topic: Tips for removing brake piston  (Read 443 times)

Online Scout63

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Tips for removing brake piston
« on: November 30, 2021, 08:29:25 PM »
Any good tips for removing a stuck brake piston from the caliper?  They are Brembo F08s.  I usually use a little compressed air while assembled, which moves the less stick one out, then disassemble, put my finger over the hole and use compressed air again to try to get the other piston out.  It just gives me the willies thinking my finger is so close to the piston. Is there a better way?
Ben Zehnder
Orleans, MA USA
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Online nc43bsa

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Re: Tips for removing brake piston
« Reply #1 on: November 30, 2021, 08:37:48 PM »
Screw a grease fitting in place of the bleed screw, pump the caliper full of grease.

Use a small C-clamp to hold the non-stuck piston in place.
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Offline ridingron

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Re: Tips for removing brake piston
« Reply #2 on: November 30, 2021, 08:51:54 PM »
Quote
  Screw a grease fitting in place of the bleed screw, pump the caliper full of grease.

Use a small C-clamp to hold the non-stuck piston in place. 

+1

I would try to pump them out with the master cylinder first. Then go with the grease gun. It is amazing to me how much pressure a grease gun can generate. Of course you're left with a bit of a mess to clean.

Online Antietam Classic Cycle

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Re: Tips for removing brake piston
« Reply #3 on: November 30, 2021, 08:56:03 PM »
When using compressed air to remove the piston, I wrap an old towel around the caliper half several times, so that when it does come out, it won't go flying across the shop.

Heating the alloy caliper half will help if the piston is an original steel one.
Charlie

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Re: Tips for removing brake piston
« Reply #3 on: November 30, 2021, 08:56:03 PM »

Online Scout63

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Re: Tips for removing brake piston
« Reply #4 on: November 30, 2021, 10:13:07 PM »
Thanks everyone.  I think I might use a c clamp and rubber to block the fluid passage as well.
Ben Zehnder
Orleans, MA USA
1971 BMW R75/5
1972 Norton Commando Combat Interstate
1977 BMW R100S - next up to unload
1978 Yamaha SR500
1979 Moto Guzzi V1000G5 - T3FB mild custom
1979 Moto Guzzi V1000SP - on the lift

Online Canuck750

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Re: Tips for removing brake piston
« Reply #5 on: December 01, 2021, 12:50:16 AM »
Sometimes the steel piston is so corroded that no measure of pressure, compressed air or grease will budge it. As a last resort I weld the tip of an old bolt to the centre of piston and let it cool. Attaching a wrench to the bolt head I then turn the bolt / piston out, works every time.
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Offline Perazzimx14

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Re: Tips for removing brake piston
« Reply #6 on: December 01, 2021, 04:36:25 AM »
I used a channel locks and torch to get them out of the caliper. The pistons and seals were junk so scarring/marring the old ones was not of concern.   
It's the ones who've cracked that the light shines through!

Offline smsw

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Re: Tips for removing brake piston
« Reply #7 on: December 01, 2021, 08:02:10 PM »
Sometimes the steel piston is so corroded that no measure of pressure, compressed air or grease will budge it. As a last resort I weld the tip of an old bolt to the centre of piston and let it cool. Attaching a wrench to the bolt head I then turn the bolt / piston out, works every time.
If a steel piston is that far gone, isn't the caliper's aluminum also toast?

Online Scout63

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Re: Tips for removing brake piston
« Reply #8 on: December 01, 2021, 08:45:57 PM »
I donít think itís very far gone. The other piston popped right out with pretty good fluid still behind it.  The caliper body looks good with nice paint.  The bleed screws came right out. I was feeling a little timid and put it down for another night.  Expelling brake pistons with air is up there with seating tire beads for causing anxiety.
Ben Zehnder
Orleans, MA USA
1971 BMW R75/5
1972 Norton Commando Combat Interstate
1977 BMW R100S - next up to unload
1978 Yamaha SR500
1979 Moto Guzzi V1000G5 - T3FB mild custom
1979 Moto Guzzi V1000SP - on the lift

Offline Perazzimx14

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Re: Tips for removing brake piston
« Reply #9 on: December 01, 2021, 08:59:19 PM »
If a steel piston is that far gone, isn't the caliper's aluminum also toast?

No the steel will rust and pit. The aluminum is usually salvageable once the picks are removed and a good cleaning.
It's the ones who've cracked that the light shines through!

Online n3303j

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Re: Tips for removing brake piston
« Reply #10 on: December 02, 2021, 09:06:51 AM »
If a steel piston is that far gone, isn't the caliper's aluminum also toast?
The caliper bore only guides and secures the piston when braking. As long as the piston is a slip fit in the bore the caliper will function as intended.

BUT: The seal between the caliper and the puck is maintained by the square sectioned "O" ring. It is imperative that the surfaces between the "O" ring and the caliper body are smooth enough to seal. Being protected by the "O" these surfaces the surfaces of the groove are usually in excellent condition.
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Online Gino

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Re: Tips for removing brake piston
« Reply #11 on: December 02, 2021, 10:53:24 AM »
I had an issue with a Kawasaki last year and made this video, may help

https://youtu.be/1GAg5IHcCBo

Gino

Online Scout63

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Re: Tips for removing brake piston
« Reply #12 on: December 02, 2021, 08:49:00 PM »
I had an issue with a Kawasaki last year and made this video, may help

https://youtu.be/1GAg5IHcCBo

Gino

Thanks Gino.  Iíve heard about that but never seen it done.

I used a small c clamp and a bit of inner tube to block the inner port, wrapped a towel around it like Charlie suggested, and a little compressed air popped it out.
Ben Zehnder
Orleans, MA USA
1971 BMW R75/5
1972 Norton Commando Combat Interstate
1977 BMW R100S - next up to unload
1978 Yamaha SR500
1979 Moto Guzzi V1000G5 - T3FB mild custom
1979 Moto Guzzi V1000SP - on the lift

Online Gino

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Re: Tips for removing brake piston
« Reply #13 on: December 03, 2021, 05:59:40 AM »
Thanks Gino.  Iíve heard about that but never seen it done.

I used a small c clamp and a bit of inner tube to block the inner port, wrapped a towel around it like Charlie suggested, and a little compressed air popped it out.

Hi Ben
Compressed air works if its not too bad but sometimes if its too bad its worth keeping the grease trick up your sleeve
Gino

Online Scout63

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Re: Tips for removing brake piston
« Reply #14 on: December 03, 2021, 07:20:21 AM »
Roger that Gino.  You make it look so easy.
Ben Zehnder
Orleans, MA USA
1971 BMW R75/5
1972 Norton Commando Combat Interstate
1977 BMW R100S - next up to unload
1978 Yamaha SR500
1979 Moto Guzzi V1000G5 - T3FB mild custom
1979 Moto Guzzi V1000SP - on the lift


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