rear brake circuit on a 5ktq

[DeWitt Harrison]

The rear proportioning valve discussion reminded me
that I've often puzzled over another odd bit in the
rear brake circuit on my car, namely the pressure reducing
valve in the right rear circuit that follows the front/rear
variable proportioning valve.

Background: In my '88 5000TQ, there is a single
rear brake circuit from the ABS unit. (This was rectified
in the ur-S4 [others?] which has independent rear circuits.)
This single circuit goes through the load sensing proportioning
valve being discussed and then to a 'T'. From the 'T' one
branch goes directly to the left rear caliper. The other
branch goes to the right caliper via an acceleration sensing
pressure reducer. The Bentley contains some unhelpful
babble about how this Thingy senses 'deceleration' and
prevents rear wheel lock-up in corners. The long axis of
this cylindrically shaped Thingy is from left to right as opposed
to fore and aft so my guess is that it senses lateral accelerations.
Both rear wheels are independently equipped with ABS
sensors to monitor wheel lock-up.

If anyone knows what up with that, I'd like to hear from
you. Question #1: Although it is reasonable to mess with
left/right brake pressure proportioning in response to lateral
accelerations, why have the system be asymmetrical? Why
not put a Thingy in both left rear and right rear branches?
Question #2: Do you suppose the ABS controller is in on
this asymmetrical plan? Would one be in trouble if he
removed this Thingy?

Cheers,

DeWitt Harrison 1988 5kcstq
Boulder, CO