Proportioning Valves/Master Cylinders

[BlueSS454]

Ok, now that I have the spindle stuff all sorted out, I'm on to the next part of the brake system.  I took a proportioning valve off of the 77 Aspen I got the one set of spindles from.  While I was in a junkyard yesterday, I noticed a 71 Charger with disc brakes that had what I would call the "correct" type of valve that would be found on a 69.  If I go back and take that valve, I would be able to use the metal brake lines for a 70 Charger and have them mount properly since the valve would be in the correct location.  If I were to use the combo valve out of the Aspen, I'd have to find a place to mount it, then custom make the brake lines.
That in turn brings me to the next question.  Would the 69 disc brake master cylinder/power booster be the right ones to use or would something else be in order here?

[Chryco Psycho]

I would get the master & proportioning valve of the 71 as a set , it will be ebtter matched to the later style brakes you are using , the 69 factory master was smaller & was designed to work with the 4 piston Kelsey Hayes cailpers 

[is_it_EVER_done?]

The Aspen valve is a "combo" valve that has the proportioning, safety, and warning light valves incorporated into one unit. Personally I like them for general use, though you will have to cut and flair all the brake lines in order to have them fit.

If you want correct looking, and easy to install, use the safety valve off the 71, but make sure you get the proportioning valve also. It will be located along the line that goes to the rear brakes, or you can use an adjustable proportioning valve from MP or other supplier.

Make sure you allways cut the JY valve out (so that the brake line ends are still attached to the valve) so you can change ends if needed.

As far as the booster is concerned, I use whatever fits the application without interference. I just did a 69 RR and used a 74 Dart booster, or you may want the 77 booster if you are going to use an aluminum "two bolt" MC. I have never found that the size/shape/manufacturer/application of the booster had much noticeable effect on braking.

The 71 booster might bolt up without drilling any new holes, so that may be a benefit to you, but any holes that may need drilled are invisible after the booster is installed. Just make sure you get the linkage that goes with the booster you choose (the many parts that go from the brake pedal to the booster lever). They are a pain to remove, but necessary.

Depending on your engine build, you may want to go with Manuel disks. this requires a smaller bore MC than the power disk only 1-1/16" or 1-1/8" MC bore. Personally I like the 1-1/16 MC as it has the best pedal feel/modulation (if you have the vacuum) otherwise I use the 15/16" MC for Manuel or low "but reasonable" vacuum. For ultra fine tuning you can try them with and without a rear residual pressure valve in the MC,

You can also use 7/8" instead of the normal 15/16"  rear brake cylinders to reduce the rear braking pressure if you run into rear lock-up problems (normally only a problem with 11 X 2-1/2", or "11 X 3" C-body" brakes), and then depending on your choice of friction materials used on the backs, and fronts.

The point of all this is that you can, and (in my opinion) should, mix and match parts for your car to maximize brake performance. JY parts are cheap, so a few different combos can be tried without much effort or expense. Just make sure you don't test things by going out onto the open road in traffic.