How hard is it to find a good mechanic??
in [Aussie Drivers]
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From: Noddy on 29 May 2010 02:47 "John_H" <john4721(a)inbox.com> wrote in message news:ms8106pmmc3qormlin0tq7dc670ulur932(a)4ax.com... > It doesn't to me, but maybe that's only because I've been listening to > tribologists for far too long! ;-) Lol :) > Also taught in high school physics (which is about as basic as it > gets) back in my day. All you young folk here can probably blame > declining educational standards. :) That's my story and I'm sticking to it :) -- Regards, Noddy.
From: Albm&ctd on 29 May 2010 03:38 In article <htqega$un6$2(a)news.eternal-september.org>, atec7 7 <""atec77\"@ hotmail.com"> says... > Oh did I remember to tell you to gagf ? > Well at least someone cares :-) Al -- I don't take sides. It's more fun to insult everyone. http://kwakakid.cjb.net/insult.html
From: Jason James on 29 May 2010 16:30 "D Walford" <dwalford(a)internode.on.net> wrote in message news:4bffaa82$0$27783$c3e8da3(a)news.astraweb.com... >> > Contact area won't make any difference to the friction coefficient but it > does make a difference to how effective a cars brakes are. > Since the way brakes stop a vehicle is to convert kinetic energy into heat > energy getting rid of lots of heat quickly is advantageous and a larger > contact area would be better at doing that. Plus the further the caliper is mounted away from the hub,the greater the leverage effect... Jason
From: F Murtz on 30 May 2010 09:15 John_H wrote: > Jason James wrote: >> "Noddy"<me(a)home.com> wrote in message >> news:4bff0e6c$0$11949$c30e37c6(a)exi-reader.telstra.net... >>> "John_H"<john4721(a)inbox.com> wrote in message >>>> >>>> What I'm disputing is the existence of any credible theory that says >>>> the increased surface area due to scoring affects the performance in >>>> any way. >>> >>> I also tend to agree, however the theory that increased contact via larger >>> surface area seems to make sense. >> >> Except, the angled sides of scoring dont present the pad with as an >> effective friction surface as parts of the disc surface that are parallel >> with the pad surface. Make sense? :-) > > No. Because the contact area is irrelevant to their performance, so > is the shape. Two sheets of corrugated iron will behave exactly the > same as two flat sheets if you were to slide them apart under the same > load. do you mean two sheets of corrugated and two sheets of flat the same width or the same surface area? > > As for contact area, disc brake examples that come to mind are those > fitted to the Triumph TR3 and Mk I Jaguar from 1956 (first road cars > to use them). They had massive pad areas compared to modern brakes > but didn't work any better (or worse). Only difference was the life > of the components. I can recall it as being common to see 25 y.o.cars > that still had their original pads. Rotors never got machined (or > replaced). >
From: John_H on 31 May 2010 00:15
F Murtz wrote: >John_H wrote: >> Jason James wrote: >>> "Noddy"<me(a)home.com> wrote in message >>> news:4bff0e6c$0$11949$c30e37c6(a)exi-reader.telstra.net... >>>> "John_H"<john4721(a)inbox.com> wrote in message >>>>> >>>>> What I'm disputing is the existence of any credible theory that says >>>>> the increased surface area due to scoring affects the performance in >>>>> any way. >>>> >>>> I also tend to agree, however the theory that increased contact via larger >>>> surface area seems to make sense. >>> >>> Except, the angled sides of scoring dont present the pad with as an >>> effective friction surface as parts of the disc surface that are parallel >>> with the pad surface. Make sense? :-) >> >> No. Because the contact area is irrelevant to their performance, so >> is the shape. Two sheets of corrugated iron will behave exactly the >> same as two flat sheets if you were to slide them apart under the same >> load. > >do you mean two sheets of corrugated and two sheets of flat the same >width or the same surface area? Either, according to the basic laws of friction. Surface area is irrelevant to the frictional force. The force (load) acting on the contact surfaces and the coefficient of friction are the relevant factors. Same principle will also apply for a sheet of flat against a sheet of corrugated, or part thereof. There are no shortage of exceptions however, as well as examples where forces other than friction apply (such as the racing slicks). I wouldn't expect brake materials to one of those exception although building materials might be. :) -- John H |