A Body - rear disc conversion, have question running rear line(s)??

[CreepinDeth]

So my 1970 A Body had drums on an Olds O rear end , but I swapped rear ends to a real 12 Bolt Chevy and the guy I bought it from years ago off this site had 4th gen Fbody disc brakes on it.

So when I installed this, it had 1/4” line from the MC to the prop valve then single 1/4” line to the frame/axle hose that was a T junction 3/16 line to ea Caliper. This never felt right, always felt like the rear wasnt grabbin. Installed an adjustable prop valve, still didnt feel right

Fast forward to today….redoing the whole brake system but have questions

I started by speaking with Tobin, from KORE3 and he recommended I go with 3/16 line to the rear 4th gen Camaro rear disc callipers. So I bought a 9” Dual diaphragm booster, and 1” bore Wilwood master with a 4 way out prop valve.
https://www.ebay.com/itm/162293088832

Now heres where Im stuck on stupid…..
The 260-11179 Wilwood prop valve (https://www.wilwood.com/PDF/DataSheets/ds715.pdf) has a single “out” for the rear, but Im not 100% sure how this plays out
Is it 3/16 to the rear, and a T junction of 3/16 dual outlets at the frame to axle point again?
If so, Im assuming I need a different flexible hose as the OEM has a 1/4 line input…..

Or Do I run an individual 3/16 brake line to each rear caliper, and have a hose line mounted to the frame the last 16” or so?? I cant find any reference pics to show me how guys ran these lines and mounted the rear brake hoses. If anyone can help point me in the right direction, be very helpful

Im assuming that ea caliper gets an individual line, but never done this.
If Im wrong or misunderstood what I needed to do, please advise

[Olds.PhD]

For both front and rear, you only have a single output from the master cylinder. It then gets split further down the line to go to each wheel, front and rear. With the front, the Wilwood proportioning valve is acting as the tee. With the rear, there is a tee in the middle of the car, as you've already found. You'll run a single line back to the tee, then split it out to each caliper.

I'm not sure why Tobin recommended the smaller line back to the tee. I'm sure he had a good reason (looking at fluid volume the master can push, if I had to guess), but I've got Ford Explorer rear discs with the Wilwood prop valve and the factory 1/4 inch line, and I can easily lock the rears up, even with 200 treadwear tires.

With the first adjustable prop valve, did you fully open it? The only thing a proportioning valve is going to do is restrict flow to the rears. If your rears are too soft with the valve fully open, its either a bleeding issue (air in the rear lines), or its a balance issue (rears aren't strong enough to pair with the fronts). Or something else is wrong with the rears (glazed pads, weaker rear pads than front, sticking calipers, etc).

[NorCal-SS]

From what I’ve seen the rear will have hard line from the MC to the rear frame crossmember. From there typically there is a flex hose that mounts to the differential with a small bracket. One side of the flex hose will have a fitting to mate up with the hard line on the rear cross member. The opposite side of that flex hose will have a TEE fitting. From the TEE fitting you can run hard line left and right to each caliper. Then a small flex hose at each caliper

[raustinss]

Smaller line will increase brake line pressure which obviously will send more pressure to the rear calipers

[Olds.PhD]

Smaller line will increase brake line pressure which obviously will send more pressure to the rear calipers

Been awhile size I took a hydraulics course, but I don't see how that is possible. The fluid is incompressible. Pressure developed at the master is the same as pressure at the caliper regardless of line size.

[TerryH432]

A single hard line to near the rear end. Then a flex line to the housing itself with hard lines going out near each caliper with a flex line going to the calipers themselves. You can buy the small tabs with keepers that will weld to the housing and match up with Wilwood or stock flex lines.

https://static1.pt-content.com/images/pt/2025/08/54697190786_21c7bcae14_b-1.jpg (https://flic.kr/p/2rkppcy)

[CreepinDeth]

Soooo I called Inline Tube today

Turns out theres a part HLF01 they sell to convert the 7/16-24 female fitting
on the frame to axle SH586 line (https://www.inlinetube.com/products/sh586) I bought to 3/8-24 to accept 3/16 line.

https://www.inlinetube.com/products/hlf01

So I am running the RO from the prop valve to the single stainless braided new SH586
line with the new 3/8-24 fitting that then splits at the T junction to each axle end and Im G2G

thanks all for the input
Sometimes ya get tunnel vision and cant see past the simple things