I am rebuilding the front brakes and have stripped down the calipers. The calipers appear fine, but all four pistons have corrosion on them, near the edge; the new seals will be making contact below these areas of corrosion.
Will it be feasible to reuse these pistons as they are?
A few pictures are at:
I would say not. I think you'll find that with new pads the corroded area of the pistons will be in contact with the seals. Even if it isn't, it's too close for comfort. I would definitely advise replacing them. It's not worth the risk, just to save a few quid. Mike.
If the corrosions in front of the seal in the caliper then it won't affect anything. The one in the middle looks like it'll overlap though.
too close to call if it were me i'd swap them as one sems to look as it if's just going to encroach on the seal side of things
Nope, not usable
Dump...
Dunno what car it is but even being cheap as I am I find it much much better to just get replacement calipers. I can never get the pistons to move freely if I just replace the seals.
Eh? Sounds like rubber grease is your friend. Assuming you've cleaned things properly, and there's no damage to pistons or bore.
At the risk of causing all manner of flak..... I've filed and polished corrosion worse than that out ( as an experiment ). That was a year ago, I inspected the caliper regularly, last time was yesterday - no problems. Reason I did it was to save money, and I convinced myself that, if they had been working in a disgusting state, then I wouldnt make them any worse. Brakes have been well and truly hammered ( pedal to floor fade ) and they havent gone wrong.
Ideally change them.
Steve
Hmm. On my 4 pot callipers, the pistons are chrome plated. When rust starts, the chrome has failed. Polishing this out wouldn't work.
Good point, its certainly true that replacement is the best solution. I've got a feeling that the pictures showed that his ones were as well - oh dear......
Problem with all this brake caliper stuff is, every caliper I've ever pulled apart has been corroded, even quite new stuff. If you look too hard, you always seem to end up spending money :-(
Are pistons + seal kits cheaper than the ref-furbs ? Are all the re-furbs properly done ?
Steve PS. The seal kit alone for the front of my bike was 60 quid !!!!!!!
Provided the corrosion is above the point where the seal makes contact, I'd think it ok - for a while, at least.
For my SD1, the exchange price is about 120 quid each from Rimmer Bros. Seal kits from my local factor were under 20 quid the pair. I got a pair of 4 pot calipers from a breaker that used the same pistons for a tenner - I was able to examine the pistons for rust before buying. The calipers on mine are for vented discs with dual circuits, but several common cars used a four pot system with the same pistons, so I was lucky. Rimmers also sell the pistons new - at 11 quid each.
Bike, innit. Think of the proper price and quadruple it.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required