Topic: Phnumatic Caliper Piston Popper

[OldSchool_IsCool]

Built a simple air coupler to attache to a flared brake line to force out a stuck caliper piston using a standard quick release air fitting, a pipe nipple and a small chunk of plastic tubing.

Procedure:
Screw the pipe nipple into the quick release.  Use Teflon tape to ensure an air tight fit.  Mount the assembly in your drill press and ream the inside dimension suitable for tapping.  Tap with a 10x1.25 metric tap.  Cut a few centimeters of plastic tubing and pound it into the assembly.  NOTE: this tubing is larger then your typical aquarium air hose, something close to 10mm OD.  Drive the tubing in about a half inch.  The tubing is there to seal with the flair.

If you aren't using a flair fitting, a straight 10x1.25 OD chunk of pipe could be used instead.

Here are some pictures:





Usage:
- fire up your air compressor to 100 PSI
- Connect the Piston Popper to your brake line
- wrap your caliper in some rags
- put the rag ball into a plastic bag (you don't want brake fluid flying about!)
- Set you air regulator to say 60 PSI and connect an air hose to the quick connect.
- A few gentle raps with a hammer against the piston/pad can help to get things moving.
- for stubborn pistons, dial up the pressure, but be extra careful!  The higher the pressure the greater the danger!

[Industrial Cafe]

exciting, did you get it apart?

[OldSchool_IsCool]

Yep!  dialed 'er up to the full 100 PSI and POP! out she came!  There was some normal grunge in the exterior of the piston, the innards looked good.  Unfortunately it messed up the finish so I'm redoing that. 

[Hasenkopf]

thats a good idea, but even 150 psi couldn't remove  mine!

[SOHC Digger]

I've used this method before and it does work!  Use caution though!  I've shot pistons across the garage before.  Make sure there is something to keep their movement limited.

[Industrial Cafe]

well good.

do you have a small toaster oven for curing the paint?

[OldSchool_IsCool]

Cured it with a heat gun.  Looks pretty good I must say!  Almost as good as when I got it from you!

[Industrial Cafe]

cool.
glad you got it un-schtook.

[themotoworks]

works even better with a mc hooked up, that can apply fluid pressure at up to 1000 psi, so even easier to get it unstuck

[754]

Air method is dangerous.. if you must put it in a 5 gallon pail or something stronger.

 Like the last post pointed out the brake itself will put out 10X the pressure (probably more) and is safer..

 I use the grease method, machined an adaptor, then use a grease gun... harder to cleanup, but no painteatingfluid, leaking on caliper and your shoes...

[City Boy]

Hi gang.I use a dedicated master and water.No mess to clean and saved the grease for lubing!    Rock On

[754]

Is that DOT 3 water or DOT 5 water.....

[City Boy]

Detroit River water.

[themotoworks]

Detroit River water.

dot 7 eh?

[Honda?]

Haha I used 150 psi at the shop. Pretty crazy when the piston blows outta there. Btw if you want to make things easier just use a rubber tipped blow nozzle. Put the rubber tip against the inlet hole on the caliper and give it a quick squeeze.

[mick7504]

The compressed air gets 'em out most of the time, but occasionally they come out like a bullet.
The best idea is to keep the caliper well covered with a plastic milk crate and rags if you want to blow them.
It's a good idea to err on the side of caution because there's no second chances if the piston gets out of control.
I've seen 'em richocet around the workshop like a 44 and take out overhead lights and brake fluid in the eyes is no fun.
Hydraulicing them out with the master cylinder is the safest way.
Mick

[Helmet Hair]

I recently embarked on a caliper and MC overhaul on my '82 Nighthawk, this model has the twin piston set up at the calipers. most of what I've read on here seems to deal with the single piston caliper so just in case it helps someone else here's how I went about dealing with getting two pistons out of the caliper.
I started by pumping the pistons out hydraulicly until they contacted a piece of packing about 8.5 mm thick which was set against the caliper frame on the fixed side.
This puts the internal face of the piston pretty much up against the inner seal edge in the bores, I then removed the packing and pumped the brake lever to force out one or other of the pistons, so far ?
obviously this leaves the second piston still in situ so how to get this one out ?
not wanting to pay out £25 or so for a set of piston pliers I decided go down the compressed air route. I'd read a couple of threads on the CB650 forum suggesting holding the expelled piston against the seal to maintain pressure inside the caliper and blowing out the second piston.
I know all the dangers of using compressed our and have read various accounts of piston's flying across garages so decided to try something a little safer that avoided having my fingers anywhere near a high velocity projectile.
I cut a disc shaped piece of old wet suit neoprene large enough to cover the exposed bore hole, I found that a 22mm socket was a nice couple of mil' larger diameter than the bore hole.
I placed the wrench end of the socket against the neoprene 'gasket' and clamped it all in place with a G clamp, the rotating 'pad' of the G clamp fitted nicely inside the splined end of the socket.
some rag was placed in front of the piston to catch it and a healthy squirt of compressed air was applied via the banjo bolt hole, pop, and out it came, caught by the rag, no damage to the piston, caliper, fingers or garage wall, hopefully the attached picture helps with the written description

[OldSchool_IsCool]

Thanks for the tip, HH!  and welcome to the forum!

The trick I use on my dual piston Goldwing calipers is to remove the pads, then place a strip of 1/8" plate in the caliper jaw.  Pump the master.  One piston will typically move all the way out to the plate, then the second will start to move.  Once they both make it to the plate, they will pretty much fall out with a little bit of wiggling.

BTY, be sure to watch your master and add fluid if it gets low!!

[Oette]

I have another solution:

Just get a grease gun and screw in the fitting grease nipple where the brake line ends. After 4-6 times of pumping it should be done. Worked well in my case and saves material.

Greets
Oette

[SOHC Digger]

I have another solution:

Just get a grease gun and screw in the fitting grease nipple where the brake line ends. After 4-6 times of pumping it should be done. Worked well in my case and saves material.

Greets
Oette

Yes, the grease gun method works much better.  I've been converted.

[cyclepsycho]

I have adapted a 4 ton porta-power pump to various brake caliper fittings.  Using automatic transmission fluid, it will separate ANY piston for the caliper body, no matter how long it has been held captive.  It's similar to the grease gun trick, but a lot easier to clean up.
I have a link to it on my website, but apparently, I can't post it here.

[strynboen]

+ 1 for the grease gun..safe and easy..like to have 10 fingers...

[crazypj]

I've used various methods, some fun as hell and really dangerous and some just really practical.
 Grease gun is best as it can develop a lot of pressure (mine will do max of 8,000psi)
It's messy to clean up, but, everything has to be cleaned properly anyway
 I forgot I have an adapter so made a new one 
You do need correct thread though, things go a lot smoother (bad pun intended)
 Honda calipers use 10x1.25 thread, Brembo and Suzuki mostly use 10x1.00 thread