Brake Balance

[LL - NY]

FWIW, my Mom's 2001.5 Passat (Bosch 5.1) also wore it's rears
faster than it's fronts. Mom mostly drives like a little old lady.

As Taka noted, the harder you drive, the more the fronts wear.
In the most recent Road & Track (Feb '07) Dennis Simantis,
explains in the Technical Correspondence column brake bias
and pad wear, and his conclusion is that the real cause of
un-balanced brake pad wear is brake bias rather than where
the work is being done. In a system like Bosch 5.X, where the
system decides what bias it's doing based upon situations, if
most of your braking is less than threshold, then it's possible
for the rears to do a majority of the work if that's how the system
was programmed (to reduce dive by moving the pitch point further
back). If you threshold brake more often, the wear will move further
forward b/c the need for more front brake force will be required.

LL - NY

On 1/10/07, Taka Mizutani <t44tqtro at gmail.com> wrote:
>
> Grant-
> I know that you're doing more like 80-90% of the braking in the front.
> However,
> the initial brake drag on the rears is a characteristic of most VW/Audi
> cars
> running
> Bosch 5.1 and newer, exactly how I described.
>
> If you "drive it like you stole it" all the time, then you would not see
> this phenomenon,
> but I don't know too many people that do that.
>
> When you mention your S4 and S6, both of those cars have the Lucas/Girling
> 4-pad,
> 2-piston caliper setup. I don't know how that factors in, all of the cars
> I
> was talking about
> are single-piston setups. Maybe the cars with the big brakes act a little
> differently.
>
> The brake proportioning is conducted via the ABS system, all the time- at
> least that is
> my understanding of the system, although I could very well be wrong.
>
> I did not see anything like this on my 5ktq or 200q, both pre-5.1 systems.
> I
> have only noticed
> the high rear brake pad wear on VW/Audi cars with 5.1 or 5.3 ABS.
>
> I will have to see what comes of the V70R which also has a Bosch brake
> system, I think-
> I haven't really been under the hood of that car very much. I know that
> the
> front pads in
> the V70R were fairly worn in 19k miles, the rears look fine. Maybe Volvo
> does not spec
> a calibration like VW. All 4 wheels dust an insane amount on the Volvo,
> though, so the rears
> are definitely doing something even in everyday driving. Either that, or
> having 4 piston brakes
> all around with huge rotors and pads simply makes a ton of dust.
>
> Taka
>
>
> On 1/10/07, Grant Lenahan <glenahan at vfemail.net> wrote:
> >
> > Not my experience, although the explanation sounds a little plausible -
> > but only up to a point. Read on.
> >
> > However, on more serious braking, ABS cannot do what you say and still
> > have the car brake effectively.  braking grip is proportinal to weight.
> > Weight in an Audi, on deceleration, will probably be 70% of more to the
> > front.  QED.
> >
> > Grant
> >
> >
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