The 510 Realm

ive got a Troy ermish 7/8" master cylinder on the way for my dime, have 280 zx front discs and maxima rear disks. From what I've read that's the combo to have. First question, what is the unit mounted to the strut tower beneath the master cylinder? Looks like it might be a proportioning unit or could it just be a distribution unit? All lines pass through it on the way from the master. Can I do without it if I put a proportioning valve inside the cabin? Second question, I seem to have lost my master pushrod and rubber seal for the cab side of the M/C, anyone know where to get them? What length of pushrod do I need? Do the universal ones work as long as I get one within the length requirements?

That little device is called a "shuttle Valve". What it does, should the brake system have a leak, is turn on the brake light on your dash. As long as pressure is equal, the little shuttle switch stays in the middle, a leak causes the valve to be pushed over, thus triggering the light. That is what the single wire is that goes into the top of the unit.

It is NOT a bias adjuster.

You can do without it if you must, but for simplicity of plumbing, why mess with it. You can still put a brake bias adjuster in the car, leading to the rear, I have mine right by the drivers seat.

Bias adjusters plumbed in the rear line are pretty rare for a 510 with your setup, are you sure you're going to need one?

For the BMC push rod, you can use any threaded rod, it's all about getting the length right. I no longer have a spare to measure, someone here will. Needs to be adjustable, though. I made my own for my Jetta BMC swap in my last car.

I'm probably going to put a bias adjuster in because I like to vary the bias for different activities, and I'm putting a hydraulic handbrake in as well once I get the drivetrain in and install the trans shifter cover I've got coming from datsport. I picked up a universal pushrod kit and just had to shorten the pushrod by 1/4" to make it work, now mated to my 7/8" MC which is now mounted. All I have to do now is bend up some hardline brake tubing to the 4 wheels, do some stainless braided at the wheels and I'm good to go with the brakes!

You don't need a bias adjuster. Or simply put, once adjusted for maximum rear braking to complement the fronts, you don't need to adjust it again.

I suppose if you filled the trunk with groceries you could turn the backs up slightly because of the added traction or reduce it as the gas tank empties, but then you risk forgetting to change it back after. Rather than constantly fiddling with it, place it under the hood to resist the temptation. Set and forget it.