Anyone ever have the caliper pistons re-chromed

[Shaun Chandler]

I have a dilema on my build. My caliper pistons like many others have pitting on them from years of no use. The calipers are all cleaned and honed and I have my new seals.

Here in lies the dilema, you can find replacement pistons on ebay and online machined from stainless but when installing in an aluminum caliper you now have the problem of galvanic corrosion between those two materials. I know there are small platting shops around me that could likely do it but do I have these hard chromed or just regular chromed. I wouldn't assume this would cost to much more then buying the replacement pistons and I could mabey chrome a couple other small pieces at the same time. I'm not a big fan of chrome but sometimes you need it.

I know this is probably overkill because the stainless piston in theory shouldn't be in contact with aluminum due to the thin layer of fluid. But hey I'm anal.

Any thoughts? Regular chrome, hard chrome just use the stainless ones. Has anyone had these in for a long period of time and taken them out and looked?

 

[drewpy]

stainless all the way, still going strong after 6 years

 

[Shaun Chandler]

Awesome to here Drewpy. Thanks. I know they should work in theory but I've read about alot of issues in car calipers that have stainless pistons with no sleeve between the aluminum and the corrosion effects. I'm sure it wont hurt that I'll only be riding in the spring summer and fall. Not to many winter motorcycle riders here in ontario.

 

[HoughMade]

There's a whole lot of aluminum bolted to a whole lot of steel and iron all over these bikes. Just look at the bolts holding the caliper on, for starters.

 

[Shaun Chandler]

Ya plain steel and aluminum is fine, its just when stainless and aluminum get bolted together that there is a problem. There are other metals like that that react I just know that one in particular from my previous life as a fitter. If there is a barrier between them its no problem so paint and some coatings. But I usally avoid bolting aluminum with stainless bolts. Its not a quick reaction and I beleive weather like rain cold and such also speed things up.

I've never looked into why stainless does this and not regualr steel. My assumption would be the chromium in the stainless but thats just a guess.

Thanks again guys I think I'm going to probably order the stainless pistons, I guess it all just comes down to keeping the brake system clean right.

Anyone suggest the best place to buy the pistons from? I've seen a couple different places on line. I know there wasn't an actual match for my 1978 xs400 but I know several bikes shared calipers.

Drewpy / HoughMade -if you remember who you got your pistons from please let me know who it is. and what model I should be matching . off the top of my head I thought the xs500 was a match

 

[drewpy]

got mine off ebay in germany and also got a set made at a friends work for nowt!

xs750/850 and SR500 share the same caliper and some RD's and 650 have them too, but you need to see the caliper shape to know