[Keith Seymore]

A lot of conversation here ...but one of the things I never see discussed is that the valves are not really "one size fits all".

If you look at the engineering brake release charts there are different meter/split/slope characteristics for different families of vehicles, typically based on vehicle model, body style and CG location, at curb weight and GVW.

[Actually - all of the variables in the brake system can be used to "tune" the brake balance, including friction material (size, and composition), caliper piston diameter and rear wheel cylinder diameter. They all work together as a system].

Buying a generic aftermarket combination valve off the shelf without this meter/split/slope detail is a bit like buying a generic carburetor and slapping it on, with no CFM information, expecting it to work perfectly under all operating conditions.

K