OK now so how does the LSPV work internally

[fester2au]

Guys can eanyone clear up for me how this valve actually works internally. I had mine apart while rebuilding the rest of the rear end mainyl to make sure it was OK and not all gummed up or seized. It was a bit cruddy around the end externally but internally it actually seemed OK. Seals and piston were not too bad and bore appeared fine. Anyway I've put a new kit through it and was fairly careful to lay the old components out correctly to copy reassemby but the function of it based on the internals seems a bit odd. Car is not together so I don't have issues but just intrigued.

It would appear the spring sits behind the piston and towards the plunger/pivot end. So the plunger and piston actually seem to sit in the closed position (or fully extended). It would appear the only way it works it that fluid pressure displaces the piston to create the correct flow path and that when the truck gets loaded the lever arm forces the plunger to remain shut or that additional fluid pressure is now required to overcome the spring force of the lever arm.

This doesn't entirely make sense to me but I'm sure I did'nt mix the components up and it also appears there is no other way round for the plunger/piston/spring combo to actually be fitted.

[fester2au]

Actually after refining my google search I think what I saw is correct.

The load sensing spring provides a variable force pushing
the proportioning piston up as the vehicle is loaded. As the piston is
lifted, a higher brake hydraulic pressure is required to force the piston
down resulting in higher pressure at the rear wheels."

[Struth]

I always thought (and I haven't looked into it) that the idea was to reduce brake force in the rear when the suspension is raised in order to avoid rear wheel lock up.

If more force is required to activate the valve then their will be less brake force applied to the rear brakes in proportion to the front.

I could be wrong though

Just my thoughts.

[fester2au]

I did fid a picture which I can't upload and it does show the internal layout as above but yeah I don't quite understand how that works but the pictures don't show the relationship of the flow paths. Remember it's not like an inline brake balance/bias device like typically found in race cars that just reduces the flow oriface. It has 3 lines so there is some sort of bypass function making it work.