Brake combination valve.

[Ratau]

Could any DP member tell me what the purpose off the combination valve mounted on the front crossmember is, how it operates and is this unit serviceable?

When does one need to mount the depressor on the combination valve during the bleeding process? :confused:

Did the 1982 Blazer came factory fitted with a proportion valve on the rear axle and is adjustable?

Danie

[crew84]

There are not too many articles on the combination valve. I have found that it will trap air bubbles when trying to bleed the brakes. This will cause your front brakes to pull. It is not suppose to be servicable. I think that is because there are no seals listed for it. I got lucky when I took it apart and cleaned it. It sealed. There are ways to bleed it but a pressure bleeder is the right way.
I think that it's function is a pressure equalizer between the two front calipers.

[Ratau]

CREW84

There is a rubber cap on the side off the combination valve with a push button (Valve) inside. Apparently one has to push this button to open the system for bleeding purpose. My question: When?

Danie

[dieselbegreat]

a combination valve serves two purposes: one side acts as a proportioning valve to set the front/rear ratio, which ratio is set by the factory. The other side delays the front disc brakes until the rear drum brakes contact the drums.
The proportioning valve over the rear axle further reduces the rear braking depending on load weight.