September 11, 20205 yr 4 hours ago, RC4 said: The fluid is WD40 residue, I sprayed the caliper in the hope of freeing the pistons. It was dry before doing so. Like you, I think they should move out more than this. Any tips on freeing them? Last time I had a stuck caliper (Old Suzuki) I pulled it from the bike and used compressed air to force them out. Drained out the brake fluid, then stuck a set of well used pads in and hit it with the air.
September 11, 20205 yr The pistons must move out for 2 cm. Take the caliper off the bike and open it. Use compressed air to take the pistons off and check them, there must no have sign of corrosion. Clean with white petroleum, and put some grease (without metal inside...there is also a specific one from ATE) on the orings.
September 11, 20205 yr Hi folks and thanks for the advice. I have now taken the caliper off the bike. When connected one piston was slightly better / more out than the other, see image. This was with pedal pressed and after bleeding. My plan is to replace pistons and seals if I can get them out. Not clear how you push them out with compressed air? Anyway plan to visit Honda Montesa dealer in Glasgow to seek advice and necessary parts. You can probably tell I am no mechanic! Thanks again.
September 11, 20205 yr One piston normally moves more than the other, find a way to hold it in place and you can use the peddle to force the other one out. Edge them out in turn until one pops out and you lose fluid and the other won't have far to go so won't be a hard to get out.
September 12, 20205 yr Dear RC4, once the caliper is out of the bike, you must open it, unscrewing the two screws blocking the two parts.You will find a little hole connecting the two parts. Blow air in these holes, and close with your finger the oil inner (only on one side...). Once the pistons are out, check theme, and the seals. If they are not damage, you do not need to replace theme. I hope you could understand me... sorry for my English... Have a nice day. Massimo
September 12, 20205 yr Hi Massiimo. Thanks for the advice. I took the caliper to a dealer this morning and he did as you said. It took him 5 minutes! He split the casing, freed up the pistons and told me to clean it carefully later. I have now done this and the seels are fine and the pistons are now free. See the image now. Will put it all back together tomorrow. Dealer did this foc which was great.
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