Hydroboost on a 58 -59 3100

[Hcb3200]

Metering and residual valves are the same thing that’s your 2 pound and 10 pound valves to keep pressure on the brakes when the master is on the frame.
A proportioning valve is just that it does not have a different name

Some master cylinders have the residual valves built-in. You should see it just inside the port.

Some modern proportioning valves off of GM trucks and cars have a combination valve where it’s both are proportional, and a residual all built in together

[SARBlade]

I was watching a video on proportioning valves, now I'm in the know! They are really not proportional at all but a relief valve. Drum brakes are extremely efficient at applying stopping power on little pressure where as disc brake requires much more pressure to apply stopping power to its disc. The relief valve in a drum setup is used to release pressure at a set point as to not "lockup" the wheel by the person applying the pressure and potentially losing control of the vehicle. The disc setup requires more pressure, like 10 x the amount a drum requires for the same stopping power, so there is not really a requirement for a relief valve on disc setups. This is as I now understand it. Please correct me if I'm wrong. Thanks

I'm just adding to my post so its clear, the idea of the metering of pressure is so the rear brakes have pressure when stopping, if they don't and all the pressure is applied at the front, then there could be some ass passing ground looping happening.

[Hcb3200]

for some a metering valve in this definition just holds pressure to keep the fluid from flowing back to master when no brake pressure is applied. It does not “meter” or change pressure to the brakes when applying pressure. You don’t need them as much when mounted on fire wall as this is above the brakes and fluid flows down. This keeps air from entering system when brakes are not applied. They are also call residual valves for residual pressure.

Proportions valves do what you posted keeps different pressures
Proportioning valves are frequently used in cars and other road vehicles to reduce the brake fluid pressure to the rear brakes. Due to weight distribution during heavy braking, more pressure is needed for front brakes. A proportioning valve reduces the pressure in the hydraulic lines to the rear brakes relative to that supplied to the front brakes during this heavy braking.


A combination valve does both and what most modern cars have that need them and it looks like a funny shaped brass hunk of metal.

The problem is most YouTube. Guys call the combination valve a proportioning valve. When it may be doing both and not one function. They make modern ones that just do the proportions.
And most don’t know that metering and residual are one and the same.