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 Post subject: Brake Calliper Issues
 Post Posted: Sat Apr 13, 2019 2:02 pm 
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Hi Guys,
I need some ideas please.

My F9.. 10k on the clock ..front right brake calliper has an issue. The middle of the three pistons (ABS) is jammed .

I was advised to yank it out, swap the seals and put it back all without messing with the fluid, just keeping the calliper in an upright position .

It all went to plan but the piston is still not moving..

All the parts look in good order and the old seals looked perfect to my eyes..

Any advise?

Many thanks..
Joseph


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 Post Posted: Sat Apr 13, 2019 2:24 pm 
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True Horneteer
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Are you trying to squeeze the piston out using the brake lever and hydraulic pressure?


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 Post Posted: Sat Apr 13, 2019 5:06 pm 
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JOB15 wrote:
Hi Guys,
I need some ideas please.

I was advised to yank it out, swap the seals and put it back all without messing with the fluid, just keeping the calliper in an upright position .

Many thanks..
Joseph



Did you thoroughly clean out where the seals sit? The pistons 'stick' due to a build up of dirt/corrosion behind the seal.

If you've only swapped the seals for new, then the new seals will still grip the pistons too tightly due to the dirt/corrosion behind them.

Another method/tool I've used to clean the recess, is a hex precision screw driver melted through a piece of perspex. Sharp and hard but not harder than the alloy, so no danger of damaging it.

Image

Works well... score a corner of perspex and snap it off.

:)

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 Post Posted: Sat Apr 13, 2019 11:13 pm 
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Hornet Pilot

Joined: Thu May 24, 2012 5:59 am
Posts: 88
Biggabit wrote:
JOB15 wrote:
Hi Guys,
I need some ideas please.

I was advised to yank it out, swap the seals and put it back all without messing with the fluid, just keeping the calliper in an upright position .

Many thanks..
Joseph



Did you thoroughly clean out where the seals sit? The pistons 'stick' due to a build up of dirt/corrosion behind the seal.

If you've only swapped the seals for new, then the new seals will still grip the pistons too tightly due to the dirt/corrosion behind them.

Another method/tool I've used to clean the recess, is a hex precision screw driver melted through a piece of perspex. Sharp and hard but not harder than the alloy, so no danger of damaging it.

Works well... score a corner of perspex and snap it off.

:)

That is some thing to try.
Cheers


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 Post Posted: Sat Apr 13, 2019 11:14 pm 
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Hornet Pilot

Joined: Thu May 24, 2012 5:59 am
Posts: 88
HOON98 wrote:
Are you trying to squeeze the piston out using the brake lever and hydraulic pressure?

the piston wont budge


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 Post Posted: Sun Apr 14, 2019 9:52 am 
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True Horneteer
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Joined: Mon Jul 13, 2015 8:08 am
Posts: 1884
Location: In The Garage
I've had to deal with a few frozen brake pistons in the past - I had a Kawasaki ZX7R and the six pot Tokicos were a f*cking nightmare - I ended up ditching them and fitting some Bandit 12 Nissin calipers because the Toks freezed up so often - but enough about me! back to your problem! :angel

If the piston is not moving with hydraulic pressure then you are going to have to bite the bullet and remove the caliper and try the following methods:

Compressed air - I actually managed to blow out a stuck piston once with a foot pump - but a proper garage type air compressor will be more effective - just make sure you stick a rag or something around the caliper to stop the piston going into orbit when it pops out.

Dedicated slide hammer type piston removal tool: I have one of these kits and they work well - but can fail to budge VERY frozen pistons - if you plan on working on your motorcycle brakes in the future then it might be worth investing in one of these - I found this set on Ebay for 30 quid - a few years back you couldn't get one of these kits for under 70 quid - so it's a bargain - check that one of the 12 adaptors will fit your pistons if you buy it - sizes range from 19 to 30mm - the reviews for this kit are very good.

http://tinyurl.com/y2bk6e7l

Grease Gun: only 12 quid from Screwfix. I haven't tried this but reports from people who have tried it says it works on VERY stuck pistons that the slide hammer tool can't budge - I'll definitely try this method next time I come up against a seriously frozen brake piston that has defeated the slide hammer:

The grease gun is an old trick - a lever action grease gun puts out 10,000psi,more than you will get any other way...not with air,not with an air powered grease gun either.Just a bit messy that's all.

You can see how it works here:

https://www.youtube.com/watch?v=NBmTmtuOsgw

and here:

https://www.youtube.com/watch?v=3HK1dn13bak

I know that you want to remove this piston as quickly and easily as possible, but from experience sometimes you just have to knuckle down and accept the fact that it's going to take removing the caliper and using one of the above methods to get that sucker out.

Hope this helps.


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 Post Posted: Sun Apr 14, 2019 1:04 pm 
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Hey Hoon.... i think he managed to remove the piston and change the seals.

From OP...

Quote:
It all went to plan but the piston is still not moving..

All the parts look in good order and the old seals looked perfect to my eyes..

Any advise?


... i don't think he cleaned out any corrosion or dirt build up.

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 Post Posted: Sun Apr 14, 2019 2:36 pm 
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Thanks Biggabit - my hangover from last night was interfering with my reading comprehension skills :pissed

Oh well - hopefully someone in the future searching for 'frozen pistons' will find it :angel


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 Post Posted: Mon Apr 15, 2019 1:12 pm 
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Hornet Pilot

Joined: Thu May 24, 2012 5:59 am
Posts: 88
Thanks for the effort Hoon.

Problem solved..

Today I went to the garage because my back brake pedal was pressing down way low.. I had gotten air in the system..
The mechanic discovered that the piston was now working properly , he bled it and we are all good now ..

Found out too that the middle piston is actually controlled by the back brake ...

Cheers Guys..
Happy Riding
Joe


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 Post Posted: Mon Apr 15, 2019 1:25 pm 
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True Horneteer
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Posts: 1884
Location: In The Garage
Quote:
Thanks for the effort Hoon.


Ha! No worries mate - might be useful info for you in the future :angel

Quote:
Today I went to the garage because my back brake pedal was pressing down way low.. I had gotten air in the system..
The mechanic discovered that the piston was now working properly , he bled it and we are all good now ..


Yeah - easily done.

Quote:
Found out too that the middle piston is actually controlled by the back brake ...


Crumbs! Never knew that. I've never had an ABS equipped bike so have never had to deal with that extra level of complexity.


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