Brake Balance

[Louis-Alain Richard]

LL, you're absolutely right. Newer cars with Bosch ABS 5.1 and up or ESP 8.0 and
up all use the ABS-ESP block to regulate the pressure to the rear wheels. In
fact, the only difference between this rear-wheel regulation and a normal ABS
regulation is the absence of the pump in the RW regulation. Only the valves in
the block opens to release the pressure to the rear. That's why the driver
doesn't know the ABS block is doing it's RW regulating job.

The corollary of all this: it means that the proportioning is 50-50 all the
time, unless the rear wheels are 15-20 % slower than the front wheels. Since the
rear pads are way much smaller, then it is logical that wear is faster. 

Louis-Alain



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