Sooo nice! I wish my Bronco was as far along! I went w the same proportioning valve, but Im ditching the brake booster & going with Hydroboost...
The blue thing is a residual valve and is designed to keep 2psi on the pads after you release the brakes, this is to prevent the pads from walking away from the rotor because of rotor warpage or because of vibration. Without this, sometimes you pads walk away and you get a long pedal (no brakes) the first part of the first pedal application. The 2psi model is for disk brakes, they also make one for drum brakes which I think is 8psi. This is only needed when running aftermarket (racing) master cylinders. OEM master cylinders typically have a residual valve built into the master cylinder for the exact same reasons. A proportioning valve is a different device and typically has an adjustment knob on it (aftermarket ones). These are only uses/needed with you have a single master cylinder for all 4 brakes and many OEM applications use non-adjustable proportioning valves. Most race setups use dual master cylinders, one for front one for rear and in this case you would not use a proportioning valve but instead change the MC piston diameter to match your caliper then use a mechanical balance bar to bias front/rear. And of course you would still use the residual valve, one on each MC.
How do the rear shackles work when the leaf springs compress and get longer because they straighten out.
It seams that after the shackle hit the frame then the leafs will warp or crack?
I have not seen a setup like this before