Re: Rear brake prop. DOES effect norm braking

[Aleksander Mierzwa <alex@matrix.com.pl>]

At 21:15 21.05.98 EDT, Myke456 wrote:

>I've seen conflicting messages, that its' purpose is to either reduce rear
>braking if the wheels go airborne, OR increase braking when under a load.
>Regardless of the proportioners purpose, changing out my old siezed one (used
>from Eric's VW-$45) has restored pressure to the calipers.

My understanding is that it's purpose is to prevent the rear wheels from
locking (having all four wheels locked or particularly having the rears
lock first would cause the car to skid very easily). As you are starting to
brake, the weight transfers to the front of the car and the brake prop.
valve reduces the pressure to the rear wheels to prevent them from locking.
This works like a simple two-channel (front-rear) mechanical ABS: it
provides more braking force to the wheels that have more grip. My Haynes
manual says after replacing the valve it should be adjusted. The procedure
requires special pressure gauges and therefore is a dealer-only job.


Aleksander Mierzwa
Warsaw, Poland
mailto:alex@matrix.com.pl
87 Audi 5000CS turbo (mine)
88 Renault Medallion wagon (mom's)
91 mountain bike (just in case both cars broke at the same time :-)