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Surface rust on disks

Care to do some searching for thermal conductivity of the ultimate high performance brake material - Carbon carbon? It's the stuff they used for the black heat shield tiles on the space shuttle. Thermal conductivity is not thermal transfer rate to air, it is how much heat it can transfer to the core of the material. Less is better. One piece cast iron discs are poor as they conduct lots of heat to the hub. This changes the bearings running clearance (can result in lose bearings!) and overheats the grease. Good brakes have discs either riveted, screwed or best of all fully floating on alloy bells. The alloy bell dissipates the heat and as it has thin spokes it gives a poor conductive path, reducing the heat going into the hub and bearings.

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Reply to
Peter Hill
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Fitting steel or iron rotors to a bike is a bloody good way of impacting your nuts on the tank the first time you use them in anger. The difference is really that great in my experience. Plus you get much much better wet weather performance and less heat fade at the expense of some pad life. I can live with that.

And aren't they vile. I've seen a few on 'Gary' cars in this country. Discs without calipers. Hmmm.

S/S discs wouldn't be good on a car, you'd get serious heat fade, the friction is lower[1], so you'd get less braking performance, leading to applying greater pressure, which will generate more heat, which gives more fade. Put upwith the rust. It scrapes off after half a mile or so anyway, leaving a lovely pock marked surface for the pads to really bite in to.

My current bike has S/S rotors, and by 'eck do I notice the difference from the iron rotors on the previous one.

[1]This I don't get. My S/S discs get seriously hot and stay hot for longer, yet I get lower braking performance. How can that be?. They don't retard as well, yet they get and stay hotter. I thought the heat came from the friction or is it just that S/S doesn't shed the heat as well as iron?
Reply to
Sean

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I did say 'replacement car SS discs'. Replacement discs would have to have the same o/a dimensions as existing cast iron ones. With vented discs being anything up to

25mm thick, the SS disc would have to be the same, even if it were bolted onto a redesigned 'top hat' portion. Thinner conventional SS discs could not be used without changing the 'top hat' or hub and callipers as well. So my point still stands. It would be horrendously expensive. As an engineer, I'm well aware that the braking system of any car could be modified to accept a cheaper manufactured SS disc than the way I suggested, but the discussion appeared to revolve around a simply change from cast iron discs to SS ones. Mike.
Reply to
Mike G

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