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Brake caliper piston not pushing all the way in.


Wintermute
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Okay, so I'm in the middle of changing the brake pads for the first time on my YBR125. So far so good, I've removed the caliper and taken the old ones off and given the thing a clean.


However, the manual says to push the piston all the way in. It goes part way in but I can't get it to go any further. It suggests I should open the valve and bleed the caliper,but even with this open I can't get the piston to go back further. Unless I can do his I can't fit my new brake pads, so I'm panicking a bit! :crybaby:


I'd be very grateful for any advice people can give me on how to sort this out!

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If the reservoir is full of fluid you wont be able to push it all the way back, it was probably topped up when the pads were wearing low, best thing to do is buy some fresh brake fluid and bleed the system.

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Thanks everyone. I tried giving it another clean this morning and bled it yesterday. No joy.


So, given it is quite an important part to have functioning, I'm not going to risk fiddling any more and will book it in tomorrow. To be honest it probably needs a good post-winter go over anyway...


Gutted I can't sort it, but I figure I've learnt something new anyway and it isn't worth taking a chance and making it worse or ending up with a brake that might fail...

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Hi the piston will not go all the way back easily they do take some force. Just be sure the piston is clean as already said. A pair of bars - screwdrivers should normally be able to prise the piston back. Just be sure you protect the caliper from damage

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I keep putting mine off tbh...


I read something about opening the resevoir cap (make sure it's topped up) before you try push the piston in. Might be worth a go. Also if you're doing the brake pads do the fluid to. It's proper easy if you get a hose that stops air going back, just be careful as it will strip paint :D

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I read something about opening the resevoir cap (make sure it's topped up) before you try push the piston in.

NOOOOOOO!


If you're going to push the piston(s) back in, you want the reservoir as near empty as you dare. I bleed out as much as I think I can get away with without getting air in the system before start fiddling about changing pads.

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I read something about opening the resevoir cap (make sure it's topped up) before you try push the piston in.

NOOOOOOO!


If you're going to push the piston(s) back in, you want the reservoir as near empty as you dare. I bleed out as much as I think I can get away with without getting air in the system before start fiddling about changing pads.

 

This is why you don't trust random google pages ha!


I wonder how many more weeks i can put off doing my brake pad...

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I wonder how many more weeks i can put off doing my brake pad...

 

Awesome, we both bought Chinese bikes around the same time, we both passed our tests around the same time, we both bought unreliable first big bikes at the same time, and now we can be limping everywhere at the same time too :lol:

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I wonder how many more weeks i can put off doing my brake pad...

 

Awesome, we both bought Chinese bikes around the same time, we both passed our tests around the same time, we both bought unreliable first big bikes at the same time, and now we can be limping everywhere at the same time too :lol:

 




:D I think we were doomed to WALK this earth...

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Normally the reservoir has more than enough space in there to allow the piston to be pushed back. On assembly the calliper will be fitted with new pads then system is then filled up bled and level checked. Unless you have topped up the reservoir recently with well worn pads still fitted, then yes you might need to remove some of the oil. I've never personally had to remove oil to fit new pads be it car or bike.

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Normally the reservoir has more than enough space in there to allow the piston to be pushed back. On assembly the calliper will be fitted with new pads then system is then filled up bled and level checked. Unless you have topped up the reservoir recently with well worn pads still fitted, then yes you might need to remove some of the oil. I've never personally had to remove oil to fit new pads be it car or bike.

This is true but I don't want to take the chance of me bashing in to it and sending fluid slopping all over the plastic and paintwork.

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Normally the reservoir has more than enough space in there to allow the piston to be pushed back. On assembly the calliper will be fitted with new pads then system is then filled up bled and level checked. Unless you have topped up the reservoir recently with well worn pads still fitted, then yes you might need to remove some of the oil. I've never personally had to remove oil to fit new pads be it car or bike.

This is true but I don't want to take the chance of me bashing in to it and sending fluid slopping all over the plastic and paintwork.

If your not sure of the level just fit a piece of hose to the bleed nipple and put the other end into a bottle, crack the bleed nipple open then push the piston back. Then there's little or no chance of soaking the paintwork in brake fluid.

Have some brake cleaner at hand for a clean up just in case anyway

I would never push the piston back with the reservoir cover off, your really asking for trouble you could easily end up soaking the bike in brake fluid.

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