Well, I thought I would tackle the job and I’m glad I did so far as the job has been very easy. I thought I would get away with just stripping the calliper, cleaning the rust and crud and rebuilding it!Not quite as straight forward as I first thought.I stripped the piston out and discovered there was a ridge of rust deposited around the edge and I also discovered that the piston is not made from steel, but some sort of resin material / Bakelite. Anyway, a very light rub on some 600 grit wet and dry and the rust deposit was removed.This photo shows the piston after I removed the rust.Next I realised the rust had come from the ring of metal by the seal in the casting.So a gentle rub with the 600 paper and all the rust was removed.In the process of rubbing this area of the cylinder, I realised that there must be a split in the outer seal to have let all the water in which had caused this to rust up. Sure enough, here is the split.A quick call to Lighthouse who have the service kits in stock and I’m now waiting for the post in the morning.Knowing that there is a new piston on its way I removed the internal seal from the cylinder and inserted the piston and to my surprise it got stuck despite having removed all the crud and rust! In some positions it was working, but if I rotated it a few degrees one way or another it became stuck again. I very gently rubbed the piston again on the 600 paper and now it’s a perfect fit! I will use the new piston though. But it just goes to show, what you thing is clean and back to size is not! I also rotated the piston in the cylinder after this second sanding and there was no sign of any interference, just a good close and snug fit.The service kits include the piston, inner seal and outer seal are only £13.90 plus VAT and p&p. I’ve ordered 2 sets!
