rear brake circuit on a 5ktq

[DeWitt Harrison]

Chris raises an interesting question in my mind as to whether
there is still a rear brake circuit Thingy in cars with independently
ABS modulated rear brake lines.

But anyway, as far as the '88 5000tq goes, I've finally figured
out that the need for the Thingy springs from the fact that the
rear end ride height sensing proportioning valve senses ride
height on the left side only and it not able to distinguish between
suspension deflections due to cargo loading and those due to
cornering. The Thingy partly compensates for this problem.
Inquire off line if you would like to read my long explanation.

DeWitt

> DeWitt Harrison wrote:
> 
> >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?
> >  
> >
> I don't know if it is safe to remove, but my 100, S4, A6, S6 ('92-'98) 
> says this about a unit installed between the left rear and right rear 
> brake calipers:
> "The brake pressure limiter, installed between left and right rear brake 
> calipers, is a delay-dependent brake proportioning valve that prevents 
> locking of the right rear wheel when simultaneously driving rapidly 
> around curves to the right, and braking."
> It also has adjustment and operation checks.
> 
> Sounds like your unit.  Why there isn't one for the left wheel for left 
> turns, it doesn't say.  My not very educated guess is that left turns in 
> the US aren't as tight as right turns and therefore don't need wheel 
> lockup prevention.
> 
> -Chris