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I am planning to refurbish the calipers on my 72E (M type) following a good post in this section.
While ordering materials I have though of replacing the pistons with stainless steel ones. Question is Is it a good idea? if so does anybody know where I can buy them?
Thanks
Arturo
Arturo
I've just ordered a set through Stoddart. Cheaper than Pelican.....
I think repacing anything old with new in the braking department is a good idea :)
Good luck
Advantage of course is added strength and corrosion-resistance (thus longer-lasting seals as well) compared to originals. A good bet in the long run.
great info, ordered form stoddard. thanks
Yes but why Factory never built them in SS ?????:rolleyes:Quote:
Originally Posted by richemj
Stainless Steel Pistons seem to be used quite commonly as replacements and seem to offer some advantages with regard to corrosion resistance and reduced thermal conductivity compared to either cast or conventional steel pistons.
Most of the Stainless Steel Pistons I have seen are made from an Austenitic Alloy such as 303. This alloy has Selenium additions so that it will machine and grind to a higher level of finish than more common alloys such as 304 or 316.
The Austenitic alloys do , however, have a much higher coefficient of expansion than a standard piston. Thei increase is around 70% which for a 2" diameter piston would be about an extra 3.0 thou.
This extra expansion could lead to increased seal wear unless it was allowed for and then cold clearances would be higher and may make seals more prone to leaks.
It would be better to make pistons from an alloy such as 410 which is a Martensitic steel and would have similar expansion to a typical engieering steel. This type of material would grind to a better surface finish, still have excellent corrosion resistance and also has a relatively low thermal conductivity (but a little higher than Austenitic Alloys)
The best solution may be an Alpha-Beta Titanium which would be extremely corrosion resistant, has a similar coefficient of expansion to engineering steels and an even lower thermal conductivity than Austenitic Stainless.
It may be worth acidic anodising this type of piston to reduce galling but they are used in a number of Brembo calipers and I am not 100% sure if they are anodised.
I very rarely find 40 year old steel pistons to be bad...
Stainless have been good (we use Stomski's) but basically only for S-Calipers. Plated S-Caliper pistons are almost "always" bad.
As stated herein, never a bad option but, again; I've rarely seen bad M-Caliper pistons.
Can someone comment about differences between Stomski (Pelican) at 240$ vs Stoddard at 140$ ??
Thanks !
JD
Hmm. Titanium. Sounds nice, but pricey.
Steven realized over the years that he was priced out of the market. I believe he's buying them from our supplier which I turned him on to a few years back. I'd be willing to bet he hasn't updated his website in a while. We offer full sets for $128.00 or our new Aluminum versions for $160.00.
The hard anodized aluminum is the best piston I've seen yet. No more dissimilar metal corrosion and harder than steel. All Porsche calipers from the 930 caliper on used this material for pistons and, I've found that when you go to rebuild those calipers you simply wipe them clean and reinstall. They are less than 1/2 the weight as well.
http://www.early911sregistry.org/for...1&d=1293994800