If they are not seized solid you can get the pistons out with compressed air. The trick is to get them both out at the same time. You can just pop out one at a time if you have a large rubber stopper and a g-clamp or vice. Or you can use a pair of g-clamps and use one to stop one piston from coming all the way out and the other g-clamp to allow the one you are working on to come out a bit further. The clamps also stop you from losing an eye as the piston fires out. If all this fails you will have to bolt the two halves back together and try a grease gun. Note: The caliper seals are made from EPDM. They have zero resistance to petrochemicals and most solvents. Brakleen should be fine as it is mostly acetone. (I was wrong about Brakleen before, sorry CRC company).
Hi folks Seriously stuck with a brake piston caliper. It is a rear twin pot Tokico on a ZZR1100. one piston came out but not the other. So I split the caliper and have tried the following without success: Sealey Brake piston removal pliers - only succeeded in scoring the inside of the pistons Heating piston with burner followed by repeating step 1. no good. bought a brand new grease gun specially this morning. rigged it up grease started going in but stopped. kept the pressure up and seal went in the grease gun but no movement on the caliper seal. tried step 1 again.... nope no movement 10 bar of compressed air pressure through the bleed nipple fitting. Got a good seal, no leaks in the line and nothing not a mm of movement Tried soaking in Holts brake cleaner, Petrol and WD40.... no good Boiled the caliper - and have left it to cool down. and will try again in the morning. anything else I can try? cheers!
Try pushing it into the bore with a g clamp. It’s quite possibly slightly crooked and obviously seized. Getting it straight and moving in any direction should solve the problem.
You could try using a heat gun on the caliper body , careful not to damage the caliper coating and use freeze spray on the piston itself.
No, a piston puller. Pretty expensive, but works good.I rebuilded several calipers with it. Very handy with cleaning the pistons too. Found a vid, action from 4:00 minutes:
Try Gizziracer's approach first - but if it doesn't work there is a last resort. Assuming you have the caliper halves apart - or it's a single sided one with the other side a skeleton. Drill and tap the pistons. Preferably as central as possible.Be sure not to drill into the caliper body....The couple of times I've done it,I found 6mm was big enough, but whatever you've got. Insert screw - socket head or hex head - and push the piston out. If they've seized this bad, you're going to want a piston kit anyway.
Chuck it in the freezer overnight. This has worked for me a couple of times on old HQ calipers Sent from my SM-G988B using Tapatalk
I have tried air and all sorts of other mechanical techniques without much success. Best method for me so far is to just hook up an old master cylinder and hose assembly. Fill it with fluid, bleed and then just pump until the piston(s) pops out. Do this over a dish as brake fluid goes everywhere.
Most grease guns get around 1,000psi of pressure so am surprised that did not work. Try the tapping a thread in the piston as above as if is stuck that bad the you will need a new one anyway.
Finally got it out. I boiled the caliper again then let it cool and while cooling put a G clamp on it and it moved ever so slightly. I connected the air compressor and out it popped! thanks for all the advice.