Brake piston removal "screw it!"

Yet another way to help remove those pesky li'l blighters known as the pistons in our calipers, for those cases where nothing else we've tried is moving those most sticky of stuck pistons...

First, trap one piston (the free one if there is one, obviously) using a piece of flat plate passed through the caliper, teamed up with a 2x4 behind the caliper & secured with 2 G clamps.

Then remove banjo bolt & bleed screw, slowly fill caliper with our favoured fluid (I used, wait for it... brake fluid. Other fluids are available!) through the banjo hole until it overflows from the bleed hole (thus expelling air from the caliper, air is bad!) then, keeping the caliper steady, replace the bleed screw & nip up gently taking care to not spill the fluid.

Now comes the fun bit, take one caliper *retaining bolt* and start slowly screwing into the banjo bolt hole (same thread, at least on the 900 type caliper, check first), causing a hydraulic lock... we know brake fluid doesn't compress & that one piston is held securely, so where can it go? it can only force the free (stuck but not clamped) piston out, which is what we want...

This is admittedly a slow process as we're only moving a little fluid at a time, however due to exactly this fact, we also have a huge mechanical advantage & as such this technique makes "starting off" a really stuck piston a lot easier, and once it's moved a few mm's it's usually a lot easier get it to move using one of the more well-known techniques such as the grease gun or compressed air, and less likely to result in ceiling-holes when it does free off due to the small amount of fluid being moved...

Pics to follow subject to getting the bloody camera to work again!

Small Print/legal
As with any suggestion or guide on this forum, your experience may vary, neither the site owners nor the author will be held responsible if a piston should fly out & amputate a finger/other bodily part you chose to put in the way :? , nor if you damage your caliper due to using a mismatched thread you didn't check first/any other fluids than the one suggested. All mechanical work can be dangerous, if you lack the skills/confidence to carry out this procedure please refer your calipers to a professional mechanic. All rights reserved copyright 2013 BoredBloke Publishing Ultd. :wink:

 

I've used the g clamp method effectively. I helps if you have a 3 handed alien standing by to hold everything!

 

does the snap-on guy sell those?

 

Ahh but if you use the ratchet action ones (work a bit like a caulking gun) you can get away with only a 1 handed alien to help

I think snap-on only does 6 or 7 handed & waaay too expensive for my wallet!

 

what i did was remove break caliper spring and rubber seals a gentle heat then it just screwed right out then of coarse a good clean up then new seals took me maybe 40mins total

 

You didn't have a stuck piston then ya lucky beggar!

 

totally chewed up the old piston with an 18" stillson but tossed it anyway as i had a spare one thank god, oh it was stuck alright seized would be the better word :wink:

 

Aha, and therein lies the benefit of using the BoredBloke "hydrolock/screw-it" system lol, you get to keep your piston (and if the piston is too far back you can't get a stilson on it either )

 

Small Print/legal
As with any suggestion or guide on this forum, your experience may vary, neither the site owners nor the author will be held responsible if a piston should fly out & amputate a finger/other bodily part you chose to put in the way :? , nor if you damage your caliper due to using a mismatched thread you didn't check first/any other fluids than the one suggested. All mechanical work can be dangerous, if you lack the skills/confidence to carry out this procedure please refer your calipers to a professional mechanic. All rights reserved copyright 2013 BoredBloke Publishing Ultd. :wink:[/quote]

Is it me or did anyone alse read the small leagal print fast like tey do on tv?HAHA

 

Yes, me when I proofread it... funny that isn't it, I believe it's something to do with social conditioning...

 

Is a "G" clamp a "C" clamp in America?? And who's spelling it wrong??

 

Ya we call them "C" clamps.Dont know who is right i guess its like what came first the "chicken or the egg"?

 

A Grease Gun will move the Piston out.

High Pressure Compressed Air works.

Removing the Pads and Pumping the Break Lever can do it.

Also:
L@@K closely at the Edge of the Piston that contacts the Pads.
Look for a Shadow of the Pistons exposure to elements.

You can GRAB that SHADOW with Padded Jaws of Medium-sized Channel Locks and rock it back and forth applying extraction pressure.

DO NOT make tool marks beyond where the Piston travels within the Caliper Seal.

 

You could also use a vacuum chamber. Use a bolt to close the inlet (same as outlined in 750E-II_29Rbloke's method, filling with liquid might be necessary in some cases), and make sure the bleeder is closed. Place the caliper inside of the chamber and draw vacuum. The piston should pop right out.

Oh, you don't have a vacuum chamber? Vaccum Chamber Plans

It's a bit more involved than using a grease gun, but once you have a chamber made you can use for casting parts out of resin, silencing annoying bells/ phones, and popping corn without applying heat.

 

It would be the very first time, in over 45 years, that I have heard of a Caliper Piston being extracted via "Vacuum Chamber"

Before I would fabricate a Vacuum Chamber, ...

I'd go to Duncan Donuts.
Buy a "Box-O-Joe", a dozen donuts, cream and sugars ... on-the-side.
Bring the above and the Caliper(s) to a Brake Shop.
Look for the Tech involved in the most tedious brake job.
Walk over to him and say:

"Jesus appeared to me and said you needed a break. I have coffee and donuts rather than bread and wine. Take a break. Let's have coffee!!

During the coffee break.

"Jesus also said one of you could get the Piston out from this Caliper."

 

if a guy was to take that dozen donuts to SpaceX, maybe they could get your caliper on the next resupply mission to the international space station.
then you could use donuts and vacuum !

 

Well actually, it's a G-Cramp but I said clamp as a concession to the mainly American readership :lol:

And technically, you guys are in the wrong as your C clamp came after our G clamp/cramp by dint of American English being a subsidiary language of "true" or "British" English :wink:

And Rick, I'm aware of the other methods used to extract pistons & indeed was writing this in the wake of having read some of the other methods suggested here, and with the intention that one of these methods be used to complete the job once said piston's death-grip had been broken by the "screw it" technique, in the event that any of the other methods had initially failed to move the piston. Indeed if you care to read the original post fully, you will notice that I even said so there

Vacuum sounds fun, but if I were going to that amount of trouble I think I'd just make some black powder & try a variation on the Polock cannon

 

You can put three teaspoons of water in the Caliper, ... tighten the Bleed Screw and plug the Banjo fitting.

Heat the Caliper to 215 degrees.

Use EXTREME Caution.
Steam Pressure was used to pull 80 Coal Cars.

 

And if you're scared of firing the piston thru' your ceiling (yes, I have read them lol) or just want a more "controlled" way, see the above...

Less caution required too, liquid pressure never exploded a boiler & killed it's operator 8O

Like I say, just offering up another alternative. Not trying to tread on your toes or promote one method over another.

 

Compressed air, a soft tipped air nozzle, a rubber mat (to seal the split caliper). Jab the air nozzle into the banjo port and watch your fingers. I usually end up kneeling on the caliper to hold it down and keep the piston from ejecting at 100kph.

 

The "grease gun method" works in "slow motion" so there's no danger, just a minor mess.

 

I removed the caliper and the pads, but still leaving the lines etc intact so I could use the MC to push the pistons out. Worked great and no extra tools required.


A tip when putting the calipers back in though, add a couple of drops of brakefluid on the new seals and the piston will slide in a lot easier.

 

I've done that one time before, the explosion of brake fluid convinced me it's not something I'd do again in a hurry lol (must have had some air left in the caliper too as it went EVERYWHERE!) 8O

 

"A tip when putting the calipers back in though, add a couple of drops of brakefluid on the new seals and the piston will slide in a lot easier."

Xj4ever seals come with their own little supply of special grease 8)

 

I did that with my 750 calipers. I used an old aluminum pot as a container, so nothing flew any great distance.

 

While there are many ways to solve a problem, there is always going to be..

One that is quick and easy,

One that is quick and messy,

One that is slow, but efficient,

One that is slow and frustrating,

And one that is unnecessarily complex, but really, really fun. The vacuum chamber method is the last type

Pump, pump, pump, waaaaaiit..... POP!

If I hadn't already had access to one I wouldn't have done it that way.

 

where does my steam method fall in that list, i thought it was fun

 

I tried filling my calipers with water and screwing a long bolt into the hole for the banjo fitting. The water simply leaked past the threads till the bolt reached the bottom of the threads. I then threw the water filled calipers in a pot of boiling water and made no progress.

Finally I used the grease gun method, which is abhorrent because grease is rather difficult to clean out of small passages. The method also worked on the anti-dive pistons. The bleeder nipple is impossible to remove from my grease gun fitting so the bleeder-nipple/grease-gun-fitting combo is now a tool in my toolbox.



Smart individuals would use the MC to pump the pistons free of the calipers BEFORE they disassmble the hydraulic system.

Oh and my calipers pistons pass the clunk test! Hell you can even operate the pistons(extend/retract) without the seals installed by sucking/blowing into the caliper with your mouth

Not for the Seca 750 they dont, though I think len suggests 100% silicone grease for all o-rings. Brake fluid isnt supposed to eat rubber though so brake fluid should be ok.

 

I'd imagine it'd fall under quick, potentially messy, efficient, scary and loud