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Stuck brake piston....

  • Thread starter Thread starter Seana23
  • Start date Start date
S

Seana23

Guest
Hej da. Ive got a GS with a stuck brake piston....
How do i get it out???
Air line, mole grips, large hammer!!?
Ive soaked it in WD40 but its still stuck...
What can i try now?

Thanx all.
Seana
XXX
 
Air line works well. The piston may shoot out when it releases so protect it with a rag, and keep your fingers clear.
 
I had a really stuck one and had to use a combination of everything above: PB Blaster (penetrating oil, better than wd-40; thank you GSR!), air line into the caliper with one hand, holding the caliper down to the bench with the other (clamps were not enough) AND a buddy with vise grips pulling on the piston!! :eek:

Hopefully yours will be easier, just keep going at it! :D
 
If all else fails, thread a bolt in the banjo bolt hole of the caliper, loosen the bleeder screw, put the end of a grease gun on the alemite fitting and pump away.

if you don't have a grease gun, pack the banjo bolt hole with grease and thread a bolt into the hole-repeating as necessary.
 
Is there enough of the piston to grab with a bench vise?
If so you'll get much more leverage to pull and twist at the same time.
 
I tried air, no go, ended up with a pipe wrench on it.

Be warned if you do that it will be unusable afterwards, and check your cylinder bore very closely!

Actually... is this the brake caliper piston or the master cylinder piston?
 
I always reconnect the original brake lever, bleed the system roughly using a vacuum pump and just work the piston out by using the brake lever. Always works. in case of multiple pistons, you'll have to think of a way to stop the other piston(s) moving too far out.
Once all the pistons have a mm or so left, you can usually wiggle them out by hand.

Be very very careful with air pressure. I saw someone try that, he shot the piston through the roof and never found it back
 
Last edited:
Excelent, thanx all. I dont want to write off the piston (brake caliper piston by the way) so ill try the Penetrating fluid first and work up to mashing it up.
Thanx again, ill let you know what eventually works...


Seana
XXX
 
Put an o-ring between the air and where the line bolts in. Push down hard. Mine popped out.
 
Good news Peeps. They came out!! Using the Ole Screwdriver and Angle grinder Spanner Lever trick... One either side under the lip ov the piston and plenty ov WD40, and..... Pop! Out they came.
Thanx for your kind advise.

XXX
 
Glad to hear you got it out! Now the fun part to inspect that cylinder bore and make sure she's all hunky dory for a newey...
 
ok, ive cleaned it up and oiled the seals... is there a knack to getting the pistons back in straight, so they dont wedge into the cylinder? thought maybe a vice that gives an even pressure when pushing it back in??? any other way?

Seana
XXX
 
Put a little bit of air pressure into the banjo bolt hole and place the brake fluid lubricated piston squarely over the dust boot. air pressure will cause the dust boot to go around the caliper piston allowing you push the caliper piston easily with your hand into it's bore (after removing the air pressure from the port) .
 
rustybronco said:
Put a little bit of air pressure into the banjo bolt hole and place the brake fluid lubricated piston squarely over the dust boot. air pressure will cause the dust boot to go around the caliper piston allowing you push the caliper piston easily with your hand into it's bore (after removing the air pressure from the port) .
Click to expand...

Man I wish I had've done that putting mine in!

I did the awkward lube up the piston, get the dust boot around the bottom, push it in and get the dust boot to pop into the recess on the top of the piston...
 
Its not the dust boot thats the problem, its the seal inside the calliper... I just cant get the pistons past it!!! I've pushed pretty hard but it wont go down... Dont want to force it cos i may ruin the seal but dont seem to be able to get them in...
I dont understand how forcing air into the calliper will help me push the piston down??!
Please advise.

XXX
 
Hmmm I had no problems with that bit... just made sure it was lubed with fluid and it slid down with some pressure.

If you get it on an angle it won't though...
 
Will the caliper piston fit into the bore w/out the seal in place? if it does and you have the correct piston seals, more than likely, you haven't cleaned out the groove well enough for the square cut seal to fit properly.
 
Thats exactly why they came out so hard too. If you have removed the seal from the groove you should have seen a bunch of built up scale. The scale has to displace something, so the seal is forced tighter and tighter against the piston. Use a nut pick and get into all the bottom corners and get all that scale out. The seal will seat further into the groove thus allowing more space for the piston to reseat and operate poroperly when its all bled down . You can use the little wire brushes on a dremel to clean the grooves in just a few minutes..
 
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