Topic: ANY IDEARS ON UNSIEZING MY CALIPER PISTON??

[chippyfive50]

I bought a secondary caliper for my pending dual disk setup, and the caliper piston will not budge....  I have done everything I can think of except heat it.
With no front wheel on, the brake lever is like a rock, and the piston just sits there mocking my lost $35.  I have also tapped(hard with a hammer) on the brake pad face.
ANY HELP OUT THERE......(besides a garbage can an another $35)

[mcpuffett]

persiverance  i think thats how you spell it, can you soak it in some freeing oil?   mick.

[volthause]

Can you get the supply side or bleed side of the caliper open? If you can, get all the old crud out as best you can, then let it soak in something highly toxic, or spray PB Blaster or WD40r in the supply side and let it sit. Maybe that will free it up.

(edit) ^heh.. beat me to it. 

[supersport_CB400F]

Use grease gun and pump it out  

[ohiocaferacer]

.....I have heard of using an air compressor to pop seized pistons out.....BE VERY CAREFUL!!

Stick the air nozzel in where the brake line goes and give it a few shots. I've heard when they come out they shoot out.

Later,
Greg
 

[rob]

BE VERY CAREFUL!!

I second that.  The first time I used an air compressor to release a stuck piston it shot off like a rocket... but it works quickly

Rob

[anparkinson]

I had one completely siezed after standing 14 years. I ended up pumping it out with a grease gun but beware - just as I was about to give up it shot out like a cannon ball. I had a local machine shop smooth the bore out and made me a lovely stainless stell piston all for 10 Pounds - about 18 bucks.

[upperlake04]

as OCR and Chippy say - use caution with the compressed air.  Might be wise to stuff a rag in and around the pad side of the piston to catch it when it ejects.   It would definitely make a mess of your bare finger if you tried to catch it.  I wrapped a wide rubber band around the tip of the air gun to help seal against the brake oil lime hole, and closed the bleed fitting. took but a second or two. Works great

[ProTeal55]

BE VERY CAREFUL!!

I second that.  The first time I used an air compressor to release a stuck piston it shot off like a rocket... but it works quickly

Rob

I third that. I popped a pistion out with compressed air, and the thing had to be dug out of my buddies garage wall. Wne right thu the drywall and fell inside the wall.
(true story )

[dusterdude]

is he still your buddy?

[chippyfive50]

NOW I HAVE AN EXCUSE TO BUY AN AIR COMPRESSOR!!! WELL, ITS UNANIMOUS, I'LL BLAST THE EFFER OUT WITH AIR CHOP CHOP.....
THANKS YALL...

[Bob Wessner]

Don't forget to license it as a lethal weapon. 

[Paul]

A note... The pistons don't always move with compressed air, Before you "Blast" it, clean as much crud from around the edges as possible and a liberal dose of WD40 or similar. The port is 1/8" bsp thread, so I put in a fitting, attached a piece of tubing / hose, Put the caliper into a tin, box, bag or other with just the hose protruding. Held the air gun and eventually after banding the air gun trigar it eventually blew out with a bang and I didn't see my dog for the rest of the day.
Another one, no matter what I tried ...no budge, Had to send it to an expert to do it.
Two more messy methods ...use brake fluid system to pump it out, or a grease gun.
Try garage air first, if it works, get the compressor ,push it back in and try again in fromt of some witnesses to justify your purchase.

[ProTeal55]

is he still your buddy?

For some reason he is 
It was his CB we were working on, so he really had nothing to say.
Since then he put up plywood in place of the drywall 

[rob]

Try garage air first, if it works, get the compressor ,push it back in and try again in fromt of some witnesses to justify your purchase.

I did this.  Only I put the piston in *backwards*.  The CB650 pistons have a lip for the dust boot to fit around, this lip got stuck past the recess for the brake seal and no amount of air would get it out.  For a while I thought I was going to have to cut the piston out of there, but eventually I hooked it up to the brake lever and pumped it out with brake fluid.  Definately a much less explosive and potentially damanaging way to get the piston out.

Rob

[Chris Liston]

I've used compressed air.  I put a towel folded over a few times on my work bench and then the caliper (piston side down) right on the towel.  Apply air and POP, you'll know when its out.  The towel takes the hit

[Jerry Rxman Griffin aka MuthaF'er]

No one has mentioned the old freezer trick. Dope em up with all the miracle solvents, etc the guys have mentioned then insert into your freezer inside a ziplock bag that has all the air sucked out(eliminates moisture from air). Provided you have not used a water based solvent and the metals contract it might give you just enough spare clearance to pop em out with a compressor or grease gun. Even with this 120psi hasn't touched the one I'm hoping to use for it's piston.
Jerry

[gregk]

I've tried both methods (air and a grease gun).  I think that the grease gun is the better but you have to spend some time cleaning the caliper out after the process.  The air method worked but like everybody else has warned, it comes out like a rocket! beware!

Greg

[Jmon99]

Dunno wether this'd work, but I once saw some guy on TV trying to free up a piston. He tried absolutely everything and just before giving up he tried hot engine oil.
He heated the oil (errr, be careful doing this) and poured it in.. ..left it over night to soak in and the next morning it moved great.

J

[upperlake04]

So Chippy - get that sucker out yet?

[cbjunkie]

yo, chipsta - did you know that you have a few nominations for "bike of the month"? Heffay is expecting you to formally accept the offer on the bike of the month thread so if you care at all go and "accept" so we can vote with you in the heap.

if you don't accept i'll pra nominate you again next month, so don't try to get out of it, it'll just keep coming back like a recurring nightmare until you accept the glory - 

[GroovieGhoulie]

Might be a bit late, but a good penetrating oil is "Mouse Milk".  Good stuff.  Used it to free a stuck motor.

[crazypj]

Compressed air usually only gets to around 125~160 max  Lever action grease gun does 4,000 to 7,000 psi. depending on size (oo, errr, miisssus )  When air fails, grease it is.
PJ

[Jerry Rxman Griffin aka MuthaF'er]

Grease gun I haven't tried. Please explain the procedure. How do you attach it or am I just missing something here?

[Magpie]

I threaded a suitable bolt into the inlet side of the caliper just snugging it down gentley, loosened the bleeder, stuck the grease gun nozzle on the bleeder and pumped until the piston moved. Just don't aim it at anything valuable because it may come out faster than you think. Worked for me. This is assuming the caliper is on your bench and not on your bike, it's easier off the bike.
Cliff.