Aluminum pistons for brake calipers

[phantom lunger]

I am looking at replacing my old pistons in my brake calipers on my formula ford. I'm not to keen to replace them with standard AP ones as the plating tends to flake off on contact with the pads and then starts to rust. I have come across a supplier of hard anodised aluminium pistons for ap brake calipers and obviously I am quite attracted to them due to weight/corrosion advantages etc. they are roughly the same cost as standard steel ones. My only concern is the heat transfer properties of aluminium. i.e will they make the brake fluid prone to boiling more than steel ones and also is there a chance they could seize upon expansion. any comments would be greatly appreciated.

[phoenix]

I'm no expert, but aluminium is over 5 times more effective at conducting heat than steel, and 15 times more effective than stainless steel.

If you can get stainless steel pistons, with no plating to flake, they would probably be your best bet, but aluminium would not appear to be a good idea.

[Speedy1]

aluminum pistons in aluminum housings is common on bicycle disc brakes
although a word of caution
it is possible to transfer enough heat to melt the plastic supply line and loose the brakes on a 65 mph downhill ! ! ! !

supply lines on a car are no doubt better?

worth a try with a temp monitor system

[AU N EGL]

Alumium pistions heat up too much. Go with Stainless Steel

[Notso Swift]

Alloy doesn't like fast heat cycles either

Anyone heard of Titanium being used? I think it would be just about the perfect material

(No, I am not suggesting you buy the for you FF, 10 sets of tyres would be a better investment to increase your return! More a general question to the masses)

[Zico]

What brake temps are involved, what type/grade of steel and what type of coating do the pistons have on them?

Would the heat treatment process of nitriding be a good thing to do for brake pistons? It would increase surface hardness, wear resistance and massively reduce the oxidisation problem you have.. Im not sure how the currently unknown brake temps would affect these qualities though. Id speak to the metalurgist at your local Heat treatments company, as if its an option.. it would probably be the cheapest one.

[Tim Falce]

I had no end of trouble with mine, the heat build up was so great it would constantly melt the seals. I ended up going back to cast callipers with steel pistons.
This was however on inboard Jaguar rear brakes so maybe if they could have been larger the problem may not have occurred.

[Notso Swift]

What about extra air flow Falcemob?

[sereneseven]

Just to add a little to this topic... hard anodized alum. pistons are used in nearly all current racing calipers (ap,alcon,brembo..etc) the key is that all of manufactures also fit some kind of heat sink in between the piston and the brake pad backing plate the most common design is a Ti spacer apx. 3/16" thick and is cross drilled to allow airflow between the pad and piston These heat sinks are available for most common sized pistons from most of manufactures separately.