Caliper rebuilds

I tried to persuade Mrs Clipper to go out for the day, leaving the way clear to put them in the dishwasher, but I don't think its gonna happen.

I'd avoid the dishwasher where brake calipers are concerned. I did the little aprilia calipers in the dishwasher and even though they came out clean, after a few weeks they would be covered in a white powdery substance. I first thought it was something to do with the dishwasher detergent or the salt. But even though I took them back off the bike and scrubbed them with brake cleaner, they kept getting that white powder reappear on the surface for ages after. I eventually got rid of it by stripping the calipers back down and soaking them in a tub of WD40 for a week or so before rebuilding them.

Never used them myself but they look ok to me. Mind you, they can sometimes take a lot of persuading to come out. Sometimes they practically twist out though using just your hands. I've always used compressed air. The pistons are very easy to damaged, so avoid any pliers or similar tools.

Bingo.

The reason they stick is the bit in the breeze gets corrosion or just surface crud. If yer getting the pistons out anyway clean em up with very fine wet n dry to stop em sticking.

I got mine all out today.
Pumping when still attached to the hydraulics last week had made it clear that at least one piston in each caliper would resist. I tried a bit of extra pneumatic pumping with a foot pump bodged into the banjo bolt hole today and the free pistons moved, but the resistant ones stayed put, so I split the calipers and tried the circlip plier trick.
I started with one of the sticky pistons, but unlike the chap on the video, I was using those cheap circlip pliers with exchangeable heads, and they clearly weren't up to the job, being seemingly made of plasticine. Before destroying the pliers totally, I moved onto the other piston in the same caliper half just to test the theory and that came out OK. So off to the hardware store and a set of fixed jaw circlip pliers later and the job was a good 'un. Well, it wasn't actually as easy and smooth as the video made it look and I did damage the wood of my workmate which was gripping the caliper bodies and I did also swear a bit.
What did surprise me was that the pistons were not steel as all other pistons I have ever encountered have been, they are some sort of alloy and indeed have a coating like teflon or similar on the "outside". I cleaned them using brake cleaner (Lidl special, seems OK considering the price) and a scourer and they came up really nice easily OK to be resused. The calipers needed a good scrub, but all looks good and scraping the seal grooves with a short bit of bamboo kebab skewer seems to have got all the crustiness out ready for the new seals to go in tomorrow without damaging the inner walls of the piston wells.
Going to try to get up early tomorrow to get on with it! Got my next trackday on 9th May but I do really need the bke to go to work when I go to the local office.