Swapping to front factory discs on my '71 Challenger. The drum brake brass proportioning valve seems to be standard across the board. When a car had disc brakes a coupler was added (for front brakes) and sealed with a copper washer.

I have an old brass factory disc proportioning/metering valve (it's toast) that I plan to use for reference and parts. I unscrewed the coupler to find a spring inside, and I thought I might have heard something drop to the floor when I pulled the spring out. I did find a lot of hard crud inside the spring, which continued to fall out as I cleaned it up. Is there anything else in there that may have fallen out like a ball bearing or something?

I guess I'm wondering if I can add the spring and coupler (and any other necessary parts incl. metering valve) to my original drum brake valve and make that work with discs, or should I just scrap it and buy a new repro?

Thanks!

Drum brakes didn't have a proportioning valve, what you have is just a distribution block. You need a real proportioning valve. There were a few different types that the factory used. I would try to find a factory valve and have it rebuilt.

Here's mine that I just refinished

If you are running front discs/rear drum there is a good chance you will have excess rear bias.

I'd keep the original drum brake setup... which is basically a "T" for the front and add a rear proportioning valve. The Wilwood valve is a good one. It can install neatly on the drivers side inside frame rail where the rear line runs.

If you are running a new master, it may not have a residual pressure valve for the rear brakes. A residual pressure valve can be added in the same spot you add the rear prop valve. Many consider this valve optional but Inline Tube, where I got most of my stuff, recommends it.

Looks great!

In the first photo, there is a brass coupler up top with a copper washer underneath. If you were unscrew that coupler there is a spring inside. Is that spring supposed hold a check ball or something? I am wondering what the function of that spring is?