Aluminum Brake Rotors

[blownb310]

Hypothetical situation for discussion. What if I cast and machined aluminum brake rotors to duplicate the cast iron ones on a 3,700 lb. Bolt EV?

EVs barely use the brakes. In the salt belt, it's even difficult to keep the rust from forming on them. A Bolt EV has an enormous amount of regen capability and can come to a complete stop without touching the brake pedal. Even if a rare panic stop was needed, I don't think you would overheat the rotor from a single stop from less than 65 mph.

Is there anything I am overlooking?

[freebeard]

Compare CNC from a billet. What alloy do you propose?

Are they ventilated and/or cross-drilled? That wold complicate things.

[blownb310]

Probably just 6061. I see that Wilwood makes hard anodized aluminum brake rotors for sprint cars. So maybe that's how they get aluminum to last in a brake disc application.

The Bolt EV front rotors are common vented units, not cross drilled.

[freebeard]

These are OEM steel, on my Superbeetle. The cryogenic tempering cost about as much as the raw part.

https://www.thoughtco.com › cryogenic-hardening-2340006
Introduction to Cryogenic Hardening of Metal - ThoughtCo
Besides steel, cryogenic hardening is also used to treat cast iron, copper alloys, aluminum, and magnesium . The process can improve the wear life of these types of metal parts by factors of two to six. Cryogenic treatments were first commercialized in the mid-to-late 1960s.

[cRiPpLe_rOoStEr]

I only remember seeing aluminium disc brakes on motorcycles, yet since some Russian cars had aluminium rear drum brakes I wouldn't be surprised if the front discs were made out of aluminium too.

[oil pan 4]

Use carbon ceramic rotors. They are lighter than aluminum. Aluminum rotor will clog up the pad and grind up the rotor.
Aluminum brake drums have steel inserts.

[Piotrsko]

7075 alum, what we used to call armor plate still melts around 1500 degrees. I know there's other alloys, but, significantly pricier. Sprint cars don't use their brakes much during the race, going sideways tends to scrub off speed and the brakes are an ancient requirement from years past.

[Vekke]

Depends how you drive, mainly the top speed. In most cases with evs will work without major problems.

You can calculate what thickness you would need when you know your top speeds and driving style. Meaning mill new brake pads thinner so you can fit thicker rotors if needed.

https://youtu.be/JwjnQqfFSGo?si=IOMTo44iGg27rHDp

My version from years back. Those can be made from sheetmetal parts quite easily. Cost was same as racing rotors from cast steel

[JSH]

I'm assuming you are looking to reduce unspring and rotating weight? An easy way to do that would be to turn down the rotors to their minimum thickness. If you want to go further there is the option of drilling. The machined rotor material itself that contacts the pad and the area around the mounting holes for the wheel studs.




Bolt brakes are larger than necessary because they are shared with the Cruze Premier.

[serialk11r]

Aluminum's melting point is too low, though typical brake pads also don't work at high temperature either. With cast iron rotors + high temp pads, performance is pretty acceptable.