A useful tool if you maintain your own brakes, is a set of Sealey VS1806 Brake Piston Removal Pliers, cheapest I've seen is £12.50 from Tools4Trade. These would allow you to turn the piston during maintenance/cleaning etc, so the entire leading edge surface can be visually checked.
Just done my calipers using the rag technique, and it did the trick perfectly 👍Get it in the top tips as a sticky!
Lid off the master cylinder, then try pushing them in a little more. It could be that one of the pistons has crabbed, so they might need to be pumped out a little again, checked for squarness to the bores, then eased back in again. Failing that, it might be that you need to pull them out for seal replacement etc. To clean the crap out of the seal locations, I use a small pick tool. There are normally three in a set, one right angled, one oblique, and a straight one. Soak the crap first with something like penetrating fluid to loosen it up. Dont scratch the bores
I *was* happy with the job... until I tried spinning the front wheel and found that with a good heave it only manages one rotation. I can also hear slight rubbing. Without the calipers the front spins freely so the bearings are fine. The discs don't get massively hot but still, it's not right.Is it worth lubricating the pistons as it advises in the Haynes manual (silicone grease)? Would that make any difference? Or, as I suspect, is it going to be crap built up behind the seals causing the seals to grip the pistons? Or the seals themselves swelling for some reason and gripping the pistons? Either way, that means a proper overhaul. Bugger.Anything I should be aware of doing a full overhaul? What's the best way to clean out the seal recesses given the difficulty in accessing them? In the past I've found muck in there that needs cleaning out.
Don't use anything other than Red Rubber Grease on brake pistons. You can use it to keep the rubber seals in place, and aid the refitting of the pots, and it will prolong the life of the rubber.Then smear it on the exposed area of the pots before pushing them back in so that the pads can be placed.I service mine just before winter kicks in and then around April when it warms up again, and it keeps them functioning perfectly all year round.