Removing stubborn brake caliper pistons

[canuck750]

I am rebuilding a set of Brembo dual bleeder calipers for a project and found a used set with pistons that refuse to budge. Rather than welding a bolt to the piston and pulling it out I clamped the flange of the piston in a vice grip secured to a bench vice.

I spun the brake caliper joining bolts into the caliper and used a long wrench to grab the bolt heads and then rotate the piston back and forth until I could pull the caliper body from the piston.





One seriously corroded piston



The opposite side body I just placed the bolts into the caliper pass through holes and used the same wrench technique



Removed the seal and vapour blasted the caliper body



To remove stuck bleeder place the caliper body in a vice, fit a 8mm wrench over the bleeder and take a brass hammer and tap down on the top of the bleeder while applying gentle pressure on the wrench to spin out the bleeder. If you tap long enough the bleeder will break free and spin out. The bleeder will be ruined but the caliper body will be saved.

[Hittman]

WOW. Never seen one that bad before! Good job!

[John A]

good tip on the bleeder, patience will save a caliper. I use a porta power hydraulic pump to get a stuck piston out.

[rodekyll]

Good save!

I use a pair of snap ring pliers -- the kind that open when you squeeze them -- for "normal" pistons.  For most stuck ones I like a blind race puller with a slidehammer.  I'll add heat if needed.  I don't care for compressed air or pumping grease.  Just a personal preference thing -- nothing wrong with it as a technique.

[John A]

yeah but were talking stuck pistons that haven't moved in 40 years David

[rodekyll]

Oh, I understand the situation demanded extreme measures, and that the piston was beyond sacrificial.  Any way to extract it without damaging the caliper is a win.  Judging from the pictures, he won big.   

[swooshdave]

It's amazing the bore doesn't look worse.

[Tom]

That piston is pretty bad.

[Stephen Hill]

The early pistons were chrome plated steel, as we see here.  The new replacements are anodized aluminum. 
I am a bit surprised at that choice of material.  Anodized aluminum also corrodes in the long run.
I am thinking of making some pistons out of stainless steel.
Anybody else done that? 
Thoughts??

Stephen Hill

[Antietam Classic Cycle]

It's amazing the bore doesn't look worse.

 :1:

I'd have chucked the caliper half in the oven first thing. Would definitely make it easier to remove the piston.

[Chesterfield]

Great idea, I like it!

[swooshdave]

The early pistons were chrome plated steel, as we see here.  The new replacements are anodized aluminum. 
I am a bit surprised at that choice of material.  Anodized aluminum also corrodes in the long run.
I am thinking of making some pistons out of stainless steel.
Anybody else done that? 
Thoughts??

Stephen Hill

Some of the replacement ones are teflon coated aluminum.

https://store.bevelheaven.com/Brake-Related-Parts/Brembo-F08-P108-Piston-Kit-38mm/

[wirespokes]

I've used stainless pistons before. Now that I've got a lathe, I'll probably make the next set when needed.

Yeah, I'd probably have heated the caliper to make removal easier.

A couple of times I've screwed a grease nipple into the bleeder hole and used the grease gun when nothing else worked. Kind of messy, but definitely an improvement over air pressure and old brake fluid spraying everywhere.

Of all the calipers I've worked on, I don't recall any of the bores being bad. Kind of interesting, huh?

[Huzo]

The early pistons were chrome plated steel, as we see here.  The new replacements are anodized aluminum. 
I am a bit surprised at that choice of material.  Anodized aluminum also corrodes in the long run.
I am thinking of making some pistons out of stainless steel.
Anybody else done that? 
Thoughts??

Stephen Hill

Yes, years ago for a Z1000 Kawasaki.
Used a thing called Eugema stainless, (turns beautifully).
They're still working.

[pete mcgee]

Well that was turning a pigs ear into a silk purse, very well done indeed.

[Sheepdog]

Good grief! That piston looks like it spent 20 years in a brining solution!

[John A]

It's a good reminder to change the brake fluid once a year ,on bikes anyway

[Tom]

Stainless steel takes longer to corrode but better option than oem.  The teflon coated aluminum cost only $27.  Seems a better cost option for most that can't make their pistons.