Topic: Brake Piston Removal

[markusarealius]

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

[volare71]

 
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.

[70CB750]

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.

[krusty]

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.

[70CB750]

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.

[Stev-o]

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. 

[tomk1960]

Here's how I do it:

https://www.youtube.com/watch?v=rHvIA_--BAs

[JMS28411 I'm no Spring Chicken]

I just use my air compressor

[trueblue]

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.

[JMS28411 I'm no Spring Chicken]

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

[trueblue]

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

[mystic_1]

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.

mystic_1

[Jerry Rxman Griffin aka MuthaF'er]

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.