Author Topic: Brake Piston Removal  (Read 4355 times)

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Offline markusarealius

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Brake Piston Removal
« on: January 31, 2012, 01:48:46 pm »
All,

I am sure someone else has thought of this but recently i trying to restore the brakes on my CB750F 78 model.  All three calipers were severly stuck and would not come out with any amount of air pressure I applied to them.

Being broke and limited resources, I decide to take my grease gun and insert it into the brake caliper (where the brake fluid line goes) and close off the bleeder valve, it worked like a charm -- give it a couple three pumps and she slowly pushes out!!  No damage other than grease clean up....

Hope it helps anyone...
Markus
1978 750F
2007 Triumph Tiger
1987 XT 350
1976 750f Bobber

Offline volare71

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Re: Brake Piston Removal
« Reply #1 on: April 26, 2013, 07:03:51 am »
 :)
I have used hydraulic pressure to ease out three caliper cylinders now and the pressure works gently.  I was amazed at the amount of curd in the caliper ranging from a 1/2 tsp to 1 Tbs (15 grams).   This is my setup using a freshly rebuilt Master cylinder.

Offline 70CB750

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Re: Brake Piston Removal
« Reply #2 on: April 26, 2013, 07:47:01 am »
Love the grease gun method.   I bake my first caliper in the oven and was able to get the piston out, but the grease gun approach is the best.


Offline krusty

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Re: Brake Piston Removal
« Reply #3 on: May 18, 2014, 10:57:33 pm »
I've used the grease gun with great results on really stubborn pistons. No special adapter required. Maybe I was lucky my grease gun was just the right size.
Here's how I do it.

I remove the injector tip from the grease gun.

Then wrap lots PTFE tape around the thread. Note the end on my gun is tapered.

The gently screw the caliper onto the gun until it is firm. DO NOT OVER TIGHTEN.
Then pump in the grease. The grease gun pressure will gently ease the piston out. BTW make sure the bleeder is closed or blocked off.

« Last Edit: May 18, 2014, 10:59:29 pm by krusty »
Honda
1976 CB750F1
1978 CB750F2
1972 CB350F
1961 C100 Cub
1962 C100 Cub
1959 C76
1963 C92
1964 C95
Suzuki
1963 M15D 50cc
1961 250TA Colleda
1961 250TA Colleda x 2 primed ready for paint and assembly
Yamaha
1977 DT175E x 2
1978 DT125E
1979 DT125F
1976 DT250E
1978 DT250G
1984 FJ1100
1990 FJ1200

Offline 70CB750

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Re: Brake Piston Removal
« Reply #4 on: May 19, 2014, 03:55:20 am »
Maybe I am luckier, since my grease gun works with the bleeder as zerk, I just hold the gun on it and pump.

Thanks for posting, I am sure there is more than one way to skin the cat. :)

Offline Stev-o

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Re: Brake Piston Removal
« Reply #5 on: May 19, 2014, 04:58:42 am »
I've used the grease gun method too.  When possible I prefer to use the bikes master cylinder to pop out the piston though - did it yesterday. 
'74 "Big Bang" Honda 750K [836].....'71 Honda 750K project.....'76 Honda 550F.....K3 Park Racer.....K5 Fiddy Dolla Special!......and a Bomber!............plus plus plus.........

Offline tomk1960

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Re: Brake Piston Removal
« Reply #6 on: May 19, 2014, 05:28:46 am »
2001 Kawasaki Vulcan 1500 Classic
1984 VF1000F Interceptor
1983 CB1100F Super Sport
1983 VF750F Interceptor
1982 CB900F Super Sport
1978 GL1000
1977 GL1000
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Offline JMS28411 I'm no Spring Chicken

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Re: Brake Piston Removal
« Reply #7 on: April 11, 2016, 09:39:48 pm »
I just use my air compressor :)
My 1977 CB550F Project

Offline trueblue

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Re: Brake Piston Removal
« Reply #8 on: April 11, 2016, 10:15:06 pm »
I just use my air compressor :)
which works fine unless the piston is stuck, and can get quite dangerous if the piston suddenly releases. The grease gun method is nice and controlled, with no chance of a piston turning into a bullet.
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Offline JMS28411 I'm no Spring Chicken

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Re: Brake Piston Removal
« Reply #9 on: April 12, 2016, 03:11:45 pm »
I just use my air compressor :)
which works fine unless the piston is stuck, and can get quite dangerous if the piston suddenly releases. The grease gun method is nice and controlled, with no chance of a piston turning into a bullet.

Low pressure quick short puff not high pressure
My 1977 CB550F Project

Offline trueblue

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Re: Brake Piston Removal
« Reply #10 on: April 13, 2016, 02:50:28 am »
I just use my air compressor :)
which works fine unless the piston is stuck, and can get quite dangerous if the piston suddenly releases. The grease gun method is nice and controlled, with no chance of a piston turning into a bullet.

Low pressure quick short puff not high pressure

If using low pressure, it definately won't remove a stuck piston.  Trust me, after 14 years as a mechanic I kinda know what I'm talking about ;)
1979 CB650Z
Nothing can be idiot proofed, the world keeps producing better idiots.
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Offline mystic_1

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Re: Brake Piston Removal
« Reply #11 on: April 13, 2016, 04:49:29 am »
Air compresses, so you have to pump a lot more in before you're applying the same amount of force as using a grease gun. 

This is also why compressed air can launch a stuck piston once it lets go, all that stored energy in the compressed air.

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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Brake Piston Removal
« Reply #12 on: April 13, 2016, 11:10:16 am »
If air pressure gets it out it is NOT stuck. Flying pistons hurt, maime, break car windows, etc.

Just get a full grease cartridge (if a mini gun) and either loosen the bleed valve and use that to pump grease into or insert the threads into the opening for the brake line in the caliper and pump away. Threads don't exactly match but that's OK so don't attempt to thread it very far.

This works. Period. End of subject. Make it easy on yourself.

Oh, may as well grease your swing arm while you have the gun out.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)