Andrew C. Green writes in reply to Phil Ethier:
>I'm not sure how true this is. I notice that most cars are
>equipped with these although the likelihood of them acting
>as a shield against flying debris seems a bit remote; ergo,
>what are they doing there? I think they act somewhat as
>air scoops to drag cooling air in. (Most shields seem to be
>opened towards the front, often with an obvious flared opening
>to grab air.) I believe that without the shields to gather air,
>the disc, more or less in the same plane as the tire, is
>spinning in a low-pressure area with perhaps a lot of turbulence
>but not much real air flow-through. Just a thought.
And a followup to that thought. Just last evening I reinstalled
the brake calipers, pads, tie-rod ends AND the brake shields.
The point here is that the disk rotors on the Jag XJ-S that I
am building are vented. That is, they are really a machined
casting of two parallel rotors with cast "spokes" between them.
Again, the idea is cooling. The "shields" fit neatly around the
inside of the rotor with no flairs on the perimeter. However,
they do have an aircraft type air scoop that delivers air to the
axis of the rotor presumably where the openings to the "spokes"
begin. This is a relatively sealed system as the shield fits
snugly so the rotor itself would function as a centrifugal air
pump to assist the scoop in collecting air.
I assume that any protection from gravel, etc. lodgeing in the
the caliper is just a by product as pretty large gravel could
be sucked into the scoop. Phil, I would install them and Andrew,
I think your thoughts are right. Just my thoughts...
Rick
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Richard O. Lindsay / __ __ __ __
Senior Research Scientist / / /_/ /_ / / /_/ /_/
Amoco Production Research / / / / /_/ /_/ / / / \
/ /_/
/
My opinions are my own, until they're worth something, at
which point they become the property of my employer...
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