Brake Caliper Disassembling Help

[Bewarethemoon]

I’m hoping someone can offer some help in clearing the hurdle I’ve stumbled at today.

When trying to disassemble my YZF R6 calipers I’ve come across a problem I thought I’d enquire about before I mess something up.

So obviously I’ve followed the guidance in the service manual.

My first problem is that not all of the pistons were forced out by the air blasted into the caliper, meaning that it’s difficult to create a decent seal to pop the remaining pistons out.

I hope this post makes sense? If anybody can offer any guidance I’d be hugely appreciative as I’m a little stuck at the moment.

Daniel.

 

[XsJosh]

Can you put the other pistons back in just a bit and hold them with a zip tie or 3 while you apply pressure?

 

[Raymond]

DANGER this might be bodging advice. When I have had pistons stuck in a brake caliper, I have taken hold of the exposed rim of the piston on one side (like at 12 o'clock) with mole grips, using a piece of cloth to protect the piston. Then, rotate the piston, like 11 o'clock - 1 o'clock and gently pull. Once it starts to rotate, it will generally come out without too much fuss.

In this case, with opposing pistons, not easy to get hold of the piston at one side. You could do what the manual says not to do and separate the two halves of the caliper? Or you could open up the mole grips so as to grip the piston at both sides (like 12 and 6 o'clock) and again try to rotate?

Hopefully, somebody will have a better suggestion.

 

[MaxPete]

...and once again, I see that a need to bring into play my translation skills - so here are the next ones:

1)

DANGER this might be bodging advice.

2)

Or you could open up the mole grips...

TRANS-ATLANTIC TRANSLATIONS:
1) "WATCH IT GUYS: This advice may be seen by some experts as an amateurish or unworkable repair method."

2) "Alternatively, you could select a large pair of vise grips from your toolbox and open the jaws sufficiently to..."

Ahhh, it is so useful to be multilingual...

 

[thuban]

I found the air pressure method makes a mess. If at all possible, I use the master cylinder to jack the pistons out. If one piston moves easily and the other is stuck, I put a block of wood to stop the one piston moving and direct pressure to the stuck piston. Have to watch the fluid level in the MC. I always jack the piston/pistons most of the way out before I disconnect the brake line for exactly the reason your having now. I would stick the one piston back in. Get a block of wood and hook up the brake line. You can bleed the system normally or use the MC in slow easy movements to bleed most of the air and let you apply pressure to the pistons. Works for me, anyway.

 

[Bewarethemoon]

Can you put the other pistons back in just a bit and hold them with a zip tie or 3 while you apply pressure?

This is definitely worth a shot!

 

[Rasputin]

I’m assuming you want them out to clean, replace seals etc. Clean and re assemble the pistons that have come out then put them back and clamp them in place and either compressed air or grease depending how stuck the others are jack them out. One May come before the other, if so clean it and replace it then clamp that one and go to the final one.
I use this.

 

[Bewarethemoon]

DANGER this might be bodging advice. When I have had pistons stuck in a brake caliper, I have taken hold of the exposed rim of the piston on one side (like at 12 o'clock) with mole grips, using a piece of cloth to protect the piston. Then, rotate the piston, like 11 o'clock - 1 o'clock and gently pull. Once it starts to rotate, it will generally come out without too much fuss.

In this case, with opposing pistons, not easy to get hold of the piston at one side. You could do what the manual says not to do and separate the two halves of the caliper? Or you could open up the mole grips so as to grip the piston at both sides (like 12 and 6 o'clock) and again try to rotate?

Hopefully, somebody will have a better suggestion.

Again, worth a shot. I’m not sure how much purchase I’ll get on the pistons as there’s not a lot exposed?

The caliper doesn’t separate into two halves. You can remove the piston bolt and gently tap the piston in that bore out, you can that see through to the opposing piston.

I plan on fitting new pistons so if I have to sacrifice these it’s not a problem.

 

[Bewarethemoon]

View attachment 166473 I’m assuming you want them out to clean, replace seals etc. Clean and re assemble the pistons that have come out then put them back and clamp them in place and either compressed air or grease depending how stuck the others are jack them out. One May come before the other, if so clean it and replace it then clamp that one and go to the final one.
I use this.

I want to have the calipers coated before I rebuild them.

Would grease be more effective and driving them out?

How would you clamp them in place?

 

[Bewarethemoon]

I found the air pressure method makes a mess. If at all possible, I use the master cylinder to jack the pistons out. If one piston moves easily and the other is stuck, I put a block of wood to stop the one piston moving and direct pressure to the stuck piston. Have to watch the fluid level in the MC. I always jack the piston/pistons most of the way out before I disconnect the brake line for exactly the reason your having now. I would stick the one piston back in. Get a block of wood and hook up the brake line. You can bleed the system normally or use the MC in slow easy movements to bleed most of the air and let you apply pressure to the pistons. Works for me, anyway.

I don’t have a master cylinder at present bug this does sound like an effective way at removing them so I may have to source a cheap set-up just for this purpose

 

[5twins]

I've always just used air. It's not messy if the caliper is drained of fluid. Grease, on the other hand, makes a whole new mess to clean up. I haven't encountered one yet that air won't remove. Sometimes if really stuck, you have to clamp the piston back into the caliper a little to break it free using a big C clamp, but once you get it moving, it'll come out. Sometimes you need to "work" it though, in with the clamp, out with the air as far as it will go, back in with the clamp, out with the air, etc. Eventually it will come all the way out.

Yes, you're going to need to re-install the pistons that came out, clamp them in place, and then the remaining stuck ones can be dealt with.

 

[Bewarethemoon]

I've always just used air. It's not messy if the caliper is drained of fluid. Grease, on the other hand, makes a whole new mess to clean up. I haven't encountered one yet that air won't remove. Sometimes if really stuck, you have to clamp the piston back into the caliper a little to break it free using a big C clamp, but once you get it moving, it'll come out. Sometimes you need to "work" it though, in with the clamp, out with the air as far as it will go, back in with the clamp, out with the air, etc. Eventually it will come all the way out.

Yes, you're going to need to re-install the pistons that came out, clamp them in place, and then the remaining stuck ones can be dealt with.

Thanks for the really informative post 5twins, I think this is the way to go.

I don’t own a c-clamp, yet. Could you recommend a size and I’ll order one right away!

 

[Bewarethemoon]

A huge thanks to everyone who’s replied, I’ll keep you all updated on my progress

 

[arcticXS]

Did you unscrew the 2 blanking plugs? Those who look like a 5 winged torx screw head?
The instructions said they should not be removed.....

Anyway, since the plugs are out, maybe some kind of expanding puller (bearing puller) used with a sliding hammer can be used?

 

[Bewarethemoon]

Did you unscrew the 2 blanking plugs? Those who look like a 5 winged torx screw head?
The instructions said they should not be removed.....

Anyway, since the plugs are out, maybe some kind of expanding puller (bearing puller) used with a sliding hammer can be used?

I did remove these as I plan on re-anodising.

Do you think a bearing-puller would be able to grip the opposing pistons?

 

[gggGary]

Use 5T's advice, what I do and yes I've done several sets of blue dot calipers. Use the old pads to help with piston holding, retracting.

 

[Bewarethemoon]

Use 5T's advice, what I do and yes I've done several sets of blue dot calipers. Use the old pads to help with piston holding, retracting.

Use the old pads to clamp the pistons in place using a c-clamp?

 

[gggGary]

Sure what ever works, the pads stick out a bit give you some better options on clamping without damaging pistons, or any piece of flat steel helps also. PS ebay has several sellers of seals and dust covers for these calipers.

 

[arcticXS]

I did remove these as I plan on re-anodising.

Do you think a bearing-puller would be able to grip the opposing pistons?

Maybe, as they have a edge/ridge at the end, more likely to work if the pistons are of a soft steelor alloy.
Are you planning to keep or replace the pistons?

 

[Bewarethemoon]

Maybe, as they have a edge/ridge at the end, more likely to work if the pistons are of a soft steelor alloy.
Are you planning to keep or replace the pistons?

I’m going to replace with stainless steel pistons