Brembo 3.0in calipers

[Harpo]

I picked up a pair of the Brembo 3.0 in calipers. I'm hoping to use these for my rear brakes. These currently have steel pistons. I want to replace with aluminum piston but there don't appear to be any available. The 48mm pistons are not compatible with these Brembo calipers.

There is a very small step (1.0mm ?) on the face of the piston but I'm sure what the purpose is or the science behind this feature.

Looking forward to input from the experts

Thanks

David

[Harpo]

I have circled the feature that I'm inquiring about

[Flojo]

this "step" is reasoned for angled pressure application on the pad.

when re-installing piston in caliper you must respect the position

please do a search, this has been outlined here many times.

here's a quote from Bill after a very quick search:

Originally Posted by Bill Verburg

there are tools that rotate the pistons, Porsche tool P84 measures the angle as well


when you pull the pads the backs should have witness marks like these

[Harpo]

Here is my rough draft of my step file for my cad

[Harpo]

So it looks like I simply need a certain amount of surface area on the leading edge. Something over 50%

[Trackrash]

So, how are you going to make this?

What alloy of aluminum?

What surface treatment will you apply?

Why not use stainless?

[Bill Verburg]

The best material for the pistons would have a low thermal transfer coefficient
Ti is best SS next best followed by steel

there are some really, really high end ones made either from ceramic or w/ ceramic buttons

[Harpo]

Bill, I was hoping you would post on this. Why not aluminum, same rate of thermal expansion as the caliper? Titanium would be neat but I'm under the impression that the rate of thermal expansion is less and the goal was to have the caliper & piston grow at the same rate. I was planning on using aluminum because that is what I have in my "S" calipers.

Gordon, I was planning on hard coating the aluminum pistons.

Do I need grade 5 or will grade 2 suffice. I will ask my machine shop if they can machine titanium.

[Mixed76]

Stainless has low thermal conductivity but fairly high thermal expansion.

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[Bill Verburg]

Originally Posted by Harpo

Bill, I was hoping you would post on this. Why not aluminum, same rate of thermal expansion as the caliper? Titanium would be neat but I'm under the impression that the rate of thermal expansion is less and the goal was to have the caliper & piston grow at the same rate. I was planning on using aluminum because that is what I have in my "S" calipers.

Gordon, I was planning on hard coating the aluminum pistons.

Do I need grade 5 or will grade 2 suffice. I will ask my machine shop if they can machine titanium.

All the heat is generated at the pad rotor interface and readily conducts through the pad, backing plate and piston into the brake fluid, you want to minimize that thermal path, if it's a street car then by all means go w/ aluminum

[Harpo]

No plans to race this car. Do you have a source for Ti or ceramic pistons?

Thanks

David

[Bill Verburg]

Originally Posted by Harpo

No plans to race this car. Do you have a source for Ti or ceramic pistons?

Thanks

David

Porsche Motorsport