Date: Sat, 20 Jul 2002 01:37:32 +0100
Reply-To: Clive Smith <clive.harman-smith@NTLWORLD.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Clive Smith <clive.harman-smith@NTLWORLD.COM>
Subject: Re: Warped discs and silly honda theories
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Mmmmmmmmm. Mebbe, mebbe not.
Don't think the bit about rapid cooling adds up, it doesn't happen and long
periods between hard stops can't possibly do any harm - like 100 years, they
might corrode a bit but they won't warp or wear... no, can't get my head
around that at all. And when I once took an early Lancia Thema Turbo out for
quick blast up an A-road full of roundabouts every 2 to 3 miles, then parked
up on a gravel surface at night, the red glow on that gravel quite shocked
me as I walked around the front of the car - and it didn't go away for
several minutes - thats not chilling! theres lots of hub metal and wheel
thermal capacity too. P.S. Never ever noticed fade with this superb rocket
ship luxury saloon - officially timed at 139mph (just about hit 140mph in
it - once, going to my wedding, naughty but nice!)
>Unfortunately, the light-brake philosophy can carry through to a
manufacturer's more sporting cars, where enthusiasts more easily uncover its
limits."
In some cases maybe, what we call under-chassised cars - heavier cars built
on the running gear of an intrinsically lighter one. Seat here used to be an
example, using lighter weight Fiat running gear, but soon upped their discs
sizes - only when pushing the car hard on fast A roads did I suddenly
realise at corner No. 5 that this car was seriously undersprung, underdamped
and underbraked - but then I was used to Lancias, always built to handle and
stop - unless some idiots put cow-dung brake pads in them, which nearly
killed me once (I think I nearly pulled the steering off its splines, I was
pushing that pedal so hard).
But generally, I don't know about US imports but European cars all seem to
have quite amazing brakes these days, althought the cars are getting heavier
(is this the problem in the US, all that extra gear that we don't have, AC,
Cats etc). Certainly sports models are almost overbraked for most of their
users, but they are always up to the job for the one that wants to use the
car when they can.
Ah! just thought of another factor ***
*** Change the pads before they get anywhere near thin on material -now that
can cause excess disc wear and maybe warping as a result - don't wait until
they get anywehere near the metal - most mfrs put a healthy spec on this but
of course once out of warranty, things don't always get done on schedule -
driving in hilly country is very different to tooling up and down motorways
all day. ***
Clive
'88 Syncro Transporter (sans propshaft)
----- Original Message -----
From: "David Brodbeck" <gull@CYBERSPACE.ORG>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, July 20, 2002 1:18 AM
Subject: Re: Warped discs and silly honda theories
> On Fri, 19 Jul 2002, Clive Smith wrote:
>
> > Rubbish, I'd say, what they're trying to save is unsprung weight, not
> > overall weight for fuel consumption
> > If indeed they are using thinner barke disc, which surprises me greatly!
>
> Hmm...you're probably right about trying to save unsprung weight,
> though I'd guess saving money is an even higher concern. Here's an
> article that's from a 1998 Road & Track:
> http://integra.vtec.net/carmag/warped.html
>
> "As Ruiz explains, the biggest problem isn't rapid brake heating, it's
> rapid cooling. In the typical undersized passenger-car brake system, this
> shows up as high peak temperatures from a hard stop, followed by chilling
> from either long periods between hard stops or parking the vehicle. This
> is also why adding cooling ducts to an undersized brake system can make it
> even more efficient rotor-warping device. The increased cooling air
> blasting away on a hard-working small brake means the rotor will
> heat-cycle that much more rapidly, leading to warped and cracked rotors."
> ...
> "The problem is, the brakes are an easy place for the auto
> manufacturers to save a couple of dollars. Most drivers stay well within
> even the modest performance of the average braking system, and such
> systems can usually make one panic stop at the limit of the suspension and
> tires without bursting into flames. What gives is the the system's
> durability. Unfortunately, the light-brake philosophy can carry through to
> a manufacturer's more sporting cars, where enthusiasts more easily uncover
> its limits."
>
> _ _
> __ _ _ _| | | | David M. Brodbeck (N8SRE) Ypsilanti, MI
> / _` | | | | | | +-----------------------------------------------------
> | (_| | |_| | | | @ cyberspace.org
> \__, |\__,_|_|_| "Geekdom is fantastic at being AGAINST something, and
> |___/ it's hopeless at being FOR something."
> -- Andrew Orlowski in The Register.
>
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