Brake Balance

Grant Lenahan glenahan at
Thu Jan 11 20:48:03 EST 2007

I guess I have been judged to be a maniac driver :-)
..and didnt even know it.
On Jan 11, 2007, at 10:07 AM, LL - NY wrote:

> 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> wrote:
>> 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> 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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