I am trying to roughly set up the brake balance in the garage with a knob adjusting brake proportioning valve (Willwood style)..........however...........
no matter which way I turn it there is no effect on the rear brakes. Is it possible that the valve is stuck? It was fitted by the part building owner some time ago before I bought the car. Thought I would ask before pulling it to pieces and bleeding it up AGAIN!

Is fitted the corect way round ? in any case You can't really test on unles you can get up to at least 10 mph.

As for bleeding it isn't that difficult about 4 pumps should clear the air that enters -- when doing the job to minimise losss of fluid top the resevoir level up to the very top, stretch some thin polythene or cling film over and get an air tight seal using an elastic band. Assuming you have proper rubber brakes covered hoses on the car clamp them with hose nips.

How are you testing it?

I am testing it by holding the brake pedal steady with a length of timber so that the front brakes are just beginning to lock. Then trying to release the rear brakes which are discs by turning the knob. I saw an old post on here that this was the method used by racers (MNR?) to get the balance somewhere near before road testing.
I am not totally sure it is fitted the right way round cos there don't appear to be any arrows etc. However using my method above, turning the knob still has no effect on the front brakes either.
Surely if the pedal is held steady at a point where the wheels are beginning to lock then I turn the adjusting knob the front or rear should release?
Thanks for your comments anyway.

You can't set it that way

Should be an arrow on valve body indicating flow direction.

britishtrident,
can you explain why i cant set it my way?

Think about it it is fairly obvious why the method you are using can't work because the pressure is trapped in the line, winding back the valve can't release the pressure, in theory it would work with a balance bar set up but not a proprtioning valve.

Doing something really isn't required just road test starting with the valve cutting in too early.

Just a stupid question:
Could it be possible to set it the other way around, by having the propo valve restrict pressure to minimum to the rears, put pressure on the pedal to lock the fronts and then open the valve until the rears just about lock? Before road testing I mean...

Still learning about the brake valves and wishing to avoid lessons learned the hard way...

if you're determined to do it this way id ......

(bear in mind i've never done this and am just thinking as i read this)

set the rears up so nearly if not all pressure is stopped from going to them. Press the brake pedal down so the fronts are locked up and the rears turn easily, turn the valve so the rears almost are locked. Undo it a little (so less pressure is going to the rears). Let go of the brakes, turn all wheels. Press down on the pedal and see if the rears turn a little but the fronts dont.

That way you've got more pressure going to the fronts. Now go on the testing ground and see how close it is .......

at least now you've got a starting point and definately know which way to turn the valve.

Got it now thanks, sort of forgot about the pressure trapped in the line.
I still may try your method MikeR to get some sort of ball park set up.

ok, but remember, i just made that up based on what i read here. I've never done this before.