harkins (01/19/83)
bill cox is right: the proportioning valve appeared with the disc/drum combo; the locking up type situation is what demanded their use in the first place; gm just did a lousy job of engineering i'd say and/or they used a valve designed for a different weight distribution than the x-cars happened to have ernie harkins
bentson (01/23/83)
The FIAT 128's solved the problem by linking the proportioning valve to the body pitch. This was done by noting the geometry of the rear suspension. Thus the dynamic weight transfer changes (due to different loads and severity of braking) influenced the braking done by the rear wheels. Randy Bentson Colo State U - Comp Sci