Re: brakes and lonnnng downhills

[DeWitt Harrison <de@aztek-eng.com>]

On Thu, 08 Oct 1998 21:43:00 -0400,  Kirby Smith wrote:
>[ ... ]
>I am becoming ever more amazed at the responses to Phil's message.  I
>thought Phil's question was clear, but perhaps I am influenced by being part
>of the original conversation.  Let me clarify.  Upon reaching the parking
>lot at the bottom of Mt. Wash., we felt the wheels to see how hot they got.
>The fronts were warm and the rears were _warmer_.  (I've had much hotter
>wheels from marginal caliper retraction.)  This suggested to Phil that
>perhaps the brake pressure proportioning valve should have been set up
>differently after his car's UFOs were replaced.  Thus his question.  I
>expect Phil will be happy to receive any specific information on brake bias
>setup that can be effected on his 200q if any listers have this knowledge.

Right. The point of the question was largely missed. There is an adjustable
front/rear proportioning valve on many of these cars which responds to
rear cargo weight - not to disparage Phil's rear seat passengers. The valve
simply has an arm which moves as the rear suspension height changes with
loading. The point is to better utilize the rear brakes when the car is more
heavily laden since the rear wheels will be less prone to lock up during a
stop when the front/rear weight bias is moved rearward.

I think this strategy is geared more toward fast stops on flat terrain
which transfers most of the weight of a lightly loaded vehicle onto the front
tires, but less of a heavily loaded vehicle. In the absence of rapid
deceleration,
a rear cargo load could place a disproportionate burden on the rear brakes
with this system.

DeWitt Harrison
Boulder, CO
88 5kcstq