Date:         Sun, 4 Jul 2010 12:59:49 -0700
Reply-To:     Angus Gordon <birdworks@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Angus Gordon <birdworks@GMAIL.COM>
Subject:      Re: Parking brake pressure (was I've had it)
In-Reply-To:  <48F8368F-DFCA-452A-92E5-B5FF2617233D@shaw.ca>
Content-Type: text/plain; charset=us-ascii

Not to mention the ease of maintenance with disc brakes, reason enough in my book to convert every wheel you own.


Angus


Angus Gordon
Bainbridge Island WA

On Jul 4, 2010, at 11:10 AM, Alistair Bell <albell@SHAW.CA> wrote:

> oh pish posh David :) Maybe its because the English pioneered disc
> brake technology you have a bias on the 4th.
> 
> 
> Mid 50's jag, triumph, healey... and even the French in Citroen.
> 
> as to the comment that they are not needed on the rear wheels because
> the rears do relatively little braking, you must love the poorly
> adjusting Vanagon drums a lot to trot out that excuse :)
> 
> discs are simpler, they apply force predictably, and they do work
> well with ABS... lets see a drum brake ABS system, anyone?
> 
> Sprung/unsprung weight argument is a canard. If you worry about that
> you design to have the discs to be inboard, sprung weight. On
> passenger cars the difference is less important, especially when you
> consider the tire and wheel weights nowadays (talking about the trend
> to large diameter wheels).
> 
> happy 4th to all you Yanks
> 
> cheers
> 
> alistair
> 
> 
> 
> 
> 
> 
> 
> 
> rear discs have a few advantages over drums,
> On 4-Jul-10, at 9:41 AM, David Beierl wrote:
> 
> At 08:35 AM 7/4/2010 Sunday, Dave Mcneely wrote:
>> Now, if drum brakes are less effective than disc brakes, why do so
>> many vehicles have rear drums?  Vanagon content here in that
>> vanagons are built that way.
> 
> Drum brakes were the standard automotive brake for many many years,
> although my grandmother's Studebaker still used band brakes.  Some
> time in the sixties IIRC disk brakes began to be available, and there
> was discussion in the magazines like Motor Trend and Road & Track as
> to whether the handling problems from increase in unsprung weight was
> a greater disadvantage than any increase in brake performance would
> make up for.
> 
> Clearly the universe decided otherwise, and AFAIK front drum brakes
> have entirely disappeared (I wonder what the Trabant used?).  Early
> systems were mostly dual-piston, with the caliper fixed in place; my
> Saab 96 had a pivoting system where the pads started out very thick
> on one side and were even when they were worn out.  More recently
> single-piston designs with sliding calipers have been popular as
> they're cheaper to build.
> 
> Until lately nobody considered putting disk brakes on rear wheels
> because the rears do so little actual braking that it doesn't really
> make sense -- you'd end up with more unsprung weight, which is bad,
> with no particular advantage in braking, since the rear brakes in
> general have to be restrained from using their full capacity anyway.
> 
> Disk brakes do have two advantages for rear brakes -- they are
> inherently self-adjusting, and they look cool -- at least until they
> get all rusty.  I'm waiting to see what happens when all these fancy
> cars with transparent wheels start getting rusty disks and calipers;
> will they look so pretty then?  The heat from braking accelerates
> corrosion...
> 
> But if you want my bet as to why cars are being built with rear disk
> brakes (leaving aside race cars) -- I suspect it is purely cosmetic.
> 
> Yours,
> David