Press brake piston into caliper bore?, how to do that? Options

[dangqiwu]

Can't press piston into caliper bore. Any advice?


This post has been edited by dangqiwu: Jan 2, 2013 - 11:35 PM

[Nial]

Remove the rubber boot and check for corrosion.

[dangqiwu]

Remove the rubber boot and check for corrosion.

Thanks for advice. Btw, what kind of tools should I use?

[Nial]

I dont think you will need any tools, remove the brake pads, press the brake pedal once or twice, enough to push the piston out by a half inch or so, remove the rubber boot, you might need a small flat blade screw driver to wangle the metal spring clip off the outside of the boot. once the boot is removed look at the brake piston, if its nice and clean then you should be able to push it back in, However, corrosion will cause the piston to jam against the seal which is perhaps why it wont go back in. You will need to replace the piston with a new or rust free second hand one, in an ideal world you should change the seal too, but you can sometimes get away with reusing the old one if it has not suffered any damage.

[xrav22]

Remove the rubber boot and check for corrosion.

Thanks for advice. Btw, what kind of tools should I use?

Oh I would not do all that. Take out the brake pads(remembering how they go) and just get a c clamp and press the caliper back slowly moving side to side.
Make sure to remove brake resiviour cap because your fluid will rise back up, and put the cap BACK on before pressing the brakes after you are done. Or you will have to bleed brakes.

This post has been edited by xrav22: Dec 22, 2012 - 4:06 PM

[dangqiwu]

I dont think you will need any tools, remove the brake pads, press the brake pedal once or twice, enough to push the piston out by a half inch or so, remove the rubber boot, you might need a small flat blade screw driver to wangle the metal spring clip off the outside of the boot. once the boot is removed look at the brake piston, if its nice and clean then you should be able to push it back in, However, corrosion will cause the piston to jam against the seal which is perhaps why it wont go back in. You will need to replace the piston with a new or rust free second hand one, in an ideal world you should change the seal too, but you can sometimes get away with reusing the old one if it has not suffered any damage.

The piston looks OK, just several point of rust.

Would it help if I loose the bleeder screw?

Oh I would not do all that. Take out the brake pads(remembering how they go) and just get a c clamp and press the caliper back slowly moving side to side.
Make sure to remove brake resiviour cap because your fluid will rise back up, and put the cap BACK on before pressing the brakes after you are done. Or you will have to bleed brakes.

I tried with a C-Clamp but it's not working...

[xrav22]

I dont think you will need any tools, remove the brake pads, press the brake pedal once or twice, enough to push the piston out by a half inch or so, remove the rubber boot, you might need a small flat blade screw driver to wangle the metal spring clip off the outside of the boot. once the boot is removed look at the brake piston, if its nice and clean then you should be able to push it back in, However, corrosion will cause the piston to jam against the seal which is perhaps why it wont go back in. You will need to replace the piston with a new or rust free second hand one, in an ideal world you should change the seal too, but you can sometimes get away with reusing the old one if it has not suffered any damage.

The piston looks OK, just several point of rust.

Would it help if I loose the bleeder screw?

Oh I would not do all that. Take out the brake pads(remembering how they go) and just get a c clamp and press the caliper back slowly moving side to side.
Make sure to remove brake resiviour cap because your fluid will rise back up, and put the cap BACK on before pressing the brakes after you are done. Or you will have to bleed brakes.

I tried with a C-Clamp but it's not working...

No you can't loosen bleeder screw or you will have to bleed the whole system
just remove the brake filler cap beforehand to let the pressure out.
Just (I am looking at your pic for reference), take out the pads and squeeze the piston back in very slowly with one side of the c clamp on the piston and the other on the back of the brake caliper( area next to brake line connection). It will go back slowly. I have done it 100 times always works. Just make sure to put the cap back on the resivour ( how do you spell that) after you have it all reassembled , before you press the brake pedal.
Good luck.

This post has been edited by xrav22: Dec 22, 2012 - 8:58 PM

[Nial]

I dont think you will need any tools, remove the brake pads, press the brake pedal once or twice, enough to push the piston out by a half inch or so, remove the rubber boot, you might need a small flat blade screw driver to wangle the metal spring clip off the outside of the boot. once the boot is removed look at the brake piston, if its nice and clean then you should be able to push it back in, However, corrosion will cause the piston to jam against the seal which is perhaps why it wont go back in. You will need to replace the piston with a new or rust free second hand one, in an ideal world you should change the seal too, but you can sometimes get away with reusing the old one if it has not suffered any damage.

The piston looks OK, just several point of rust.

I dont know if you have succeeded yet?

When you say "several point of rust"...where abouts? it wont take much rust/corrosion to jam up a piston enough to stop it from fully returning. if that rust happens to be making contact with the seal, simply forcing it back in will not do you any favours at all. It can lead to damage to the seal which at best will leave you with leaking brakes, at worst brake failure (a little over dramatic but it can easily happen).

Using a C-Clamp to push the piston back in will easily give you enough force to return the piston home (normally you should be able to do it by hand) if that is not working then there is perhaps another issue going on that needs investigating before any permanent damage is done.

The two most common reasons for the piston not being able to be pushed in....as mentioned corrosion on the piston making contact with the seal, or the piston being forced in such a way that it is now at a slight angle to the calliper, using a c-clamp usually pushes the piston straight! unless you have tried before to lever it in using a screw driver or something?

Maybe another photo or the corrosion might help.


or am I too late and you now have it all sorted?

This post has been edited by Nial: Dec 23, 2012 - 12:23 AM

[dangqiwu]

No you can't loosen bleeder screw or you will have to bleed the whole system
just remove the brake filler cap beforehand to let the pressure out.
Just (I am looking at your pic for reference), take out the pads and squeeze the piston back in very slowly with one side of the c clamp on the piston and the other on the back of the brake caliper( area next to brake line connection). It will go back slowly. I have done it 100 times always works. Just make sure to put the cap back on the resivour ( how do you spell that) after you have it all reassembled , before you press the brake pedal.
Good luck.

Alright, I won't loose the bleeder screw. But the piston is really hard, I use the c-clamp do press it hardly but no move at all. I guess something inside stuck the piston.

I dont know if you have succeeded yet?

When you say "several point of rust"...where abouts? it wont take much rust/corrosion to jam up a piston enough to stop it from fully returning. if that rust happens to be making contact with the seal, simply forcing it back in will not do you any favours at all. It can lead to damage to the seal which at best will leave you with leaking brakes, at worst brake failure (a little over dramatic but it can easily happen).

Using a C-Clamp to push the piston back in will easily give you enough force to return the piston home (normally you should be able to do it by hand) if that is not working then there is perhaps another issue going on that needs investigating before any permanent damage is done.

The two most common reasons for the piston not being able to be pushed in....as mentioned corrosion on the piston making contact with the seal, or the piston being forced in such a way that it is now at a slight angle to the calliper, using a c-clamp usually pushes the piston straight! unless you have tried before to lever it in using a screw driver or something?

Maybe another photo or the corrosion might help.


or am I too late and you now have it all sorted?

Not yet. I guess, as you said, the piston may got stuck by seal. I'll take a photo later.
Btw, would the fluid leak if I remove the piston?

This post has been edited by dangqiwu: Dec 23, 2012 - 3:02 AM

[Nial]

Btw, would the fluid leak if I remove the piston?

Do you mean whilst the piston is removed? yes all the fluid in the reservoir will leak out so a complete system bleed will be needed afterwards. But unless the piston is corroded there is no need to remove it completely from the calliper.

If when the piston has been removed the seal is intact and has no damage has been done whilst removing the piston then it will be fine and it should not leak...just make sure everything is clean, use only new cloths to wipe things down, have somewhere clean to put parts down where there is no grit or dirt and put it all back together. If you suspect any damage to the seal then I would use this time to replace it.

What ever you do make sure everything is spotless, dont try to force anything too much.

[dangqiwu]

Here is a photo of piston. There is no rust on piston inside the rubber seal.
Still can't move it. Any trick to line up the piston and seal?



This post has been edited by dangqiwu: Jan 2, 2013 - 11:35 PM

[dangqiwu]

I found the instruction to remove caliper. It says, "Disconnect brakeline from caliper. Plug brakeline to prevent fluid spillage. Remove caliper mounting bolts or slide pins if necessary. Remove caliper from torque plate."

Anyone teach me what it means to "plug brakeline to prevent fluid spillage"? Thanks!

[Smaay]

dont worry about doing that. if you need to push the pistons back in just use a large C clamp and close the ends on the back of the caliper and the piston. it will go in fairly easily

[Nial]

The piston does look clean so I guess not corrosion thats stopping it from going back in.

Using a C-clamp, although a good idea will only really work if the piston is lined up correctly.

What I would do is (carefully) using a screw driver try and push the piston in with moderate force, work the way around the piston at 12 oclock, 3 oclock, 6 oclock and so on.....you will suddenly (well you should) suddenly feel it give and start to move back into the caliper....then you should be able to finish the job with the c-clamp.

[dangqiwu]

Thanks guys. Finally it moves!!!
The point is the c-clamp should press in the center of the piston with a steel plate or an old brake pad. My mistake was to press piston on the edge.

[xrav22]

Thanks guys. Finally it moves!!!
The point is the c-clamp should press in the center of the piston with a steel plate or an old brake pad. My mistake was to press piston on the edge.

You can press on the sides but rotate around to make equal presure.