SS pistons?

[vxah]

I am soon going to rebuild the aluminium AP brake calipers on my Carlton and of course the pistons are as rusty as a horseshoe! So the general replacement it seems,as one cannot get originals,is to use stainless steel copies... I have this nagging worry about the corrosion problem caused by the dissimilar metals? Having had a google about has not really helped as people seem to fit them and not worry where others say it's madness and you will be needing new calipers in a year or two!

Is there any of you out there who know the answers? have done the same job and had no issues years later?
Any help would be appreciated....

[Scuffers]

some makers do use stainless, but I am not a huge fan of it, as it does have long term issues with electrolysis.

better to use decent billet ali (like 6061-T6) then have them hard anodized.

[vxah]

Thanks scuffers,although i did read ali is bad news as it transfers heat from the pads to the brake fluid too easily...just what you don't want!
Would be nice to find someone who has used stainless for a long time and inspected the calipers recently?

[Scuffers]

vxah said:

Thanks scuffers,although i did read ali is bad news as it transfers heat from the pads to the brake fluid too easily...just what you don't want!
Would be nice to find someone who has used stainless for a long time and inspected the calipers recently?

if heat transfer is an issue (and that's a big IF), then titanium is the other option.

to be honest, I have not seen any issues using ali pistons from a heat perspective, but if this is a problem, just use ceramic buffers on the back of the pads.

with road car callipers, to get the brake fluid to boil (as in decent new stuff) required the calliper temps to be over what the seals can deal with anyway, most issues with this are down to fluid contamination.

[randy]

I've seen heat issues with ali pistons but only in REALLY extreme use. Also I've seen issues with corrosion in anodized ali pistons but then they wear probably better than stainless which can score. Bottom line is whatever material you use register that road cars need dust shields that are in good condition and no brakes last forever.

[vxah]

Thanks Randy,can't fit dust shields to it so it's no wonder the pistons rusted so bad! One does have to question why Lotus built it that way,it is a road car after all!
Most likely i will fit the stainless jobbies and try to keep it out of the wet!