Brakebooster not working or?

[elacruze]

I'm not following what elacruze is saying about a hold off?   The shoes rest against the large stud on the top of the backing plate and adjust on the bottom end, (with the adjuster) this all has nothing to do with a residual pressure valve's function.

Terminology failure.
'Hold off valve' is Per's words. Technically it is a 'Residual pressure valve'. I used his term communicating with him.

"The struggle for definition is veritably the struggle for life itself."
--Thomas Szasz

A 'residual pressure valve' prevents fluid from returning to the master cylinder from the brake cylinder(s) _below a specified pressure._ The brake shoes do indeed rest on the top stud while assembling, but not after the system is adjusted, bled, and put into service. The cylinder pistons move the shoes off the stud as far as necessary to press them against the drum, then the residual pressure valve holds them out there against the effort of the return springs. From Wilwood; (Summit racing)
http://www.summitracing.com/parts/WIL-260-1876/
Ideal for drag racing, Street Rods, and many off-road applications, these inline residual pressure valves from Wilwood retain a minimum brake line pressure to help eliminate excessive pedal travel. These 2 lb. valves are used in disc brake applications where the master cylinder is mounted below the horizontal plane of the calipers, and fluid drainback occurs, causing excessive brake drag. With drum brakes, 10 lb. valves are used to compensate for return spring tension in the drums. They're made from billet aluminum and are color-coded for easy identification."

This, and possibly air as well, sound like part and parcel of Per's problem.

If the brakes are not adjusted close to begin with, and the master cylinder doesn't have enough volume to push hard against the drum before it runs out of stroke, you get no brakes in the rear.

[Belgium R/T -68]

Where do you mount those ones? One for each side?

Per