Anyone proficent with 1967 Mustang power disc brakes?

[67428GT500]

I am not happy with the stopping power of my factory disc brakes. Everything is new/rebuilt.  Even stepping on the pedal with a good amount of force. I used the centering tool to keep the distribution valve centered when bleeding and there is no air in the system.

[67xr7cat]

My 67 Cougar always stopped great. Power brakes?

[67428GT500]

Yes. It's a Shelby.  Booster Dewy did the Booster. The Master is a new unit from NAPA, The Distribution Block was a New Stainless Steel Brake item, all the lines are new and the residual pressure valve in the rear was rebuilt. There isn't anything that wasn't rebuilt or replaced.
                                                                                                    -Keith
                                                                                                   

[67xr7cat]

Stock setup 4 piston calipers? First thing see how much vacuum have at the booster. Really need 15" or more at idle.

[67428GT500]

I have exactly 15" at idle. Yes, stock KH 4 piston calipers. Rear drum are 11X2.5"

[67xr7cat]

Well I'd start with the basics have someone apply the brakes and make sure the front and rear brakes apply. The 4 piston calipers tend to seize, but new or rebuilt should not be an issue although if they sat on a shelf long time never know. Bottom line the pistons all should move freely.
Beyond that how is the pedal?  If the power booster not working it will be hard. With car off you should be able get 2 or 3 brake applications before exhausting the  booster vacuum reserve and pedal getting hard. If not could be a bad check valve at the booster or a bad booster. If you loose the reserve a after a day or two same deal, is leaking.

[67428GT500]

No issues with the booster at all. The bias light is out as well. I used the centering tool. The rears are adjusted so they just drag.  I am also running Hawk pads. 

[machyoung]

Even new parts aren't up to the task sometimes. Are you certain that the mc is the correct one for your application? SSB dist block? I put all new on one of my Mustangs and fought an "impossible to bleed" situation for weeks before just sucking it up and replacing the brand new prop valve w/ a new prop valve. Fixed. Perhaps try replacing the new dist block/rebuilt  pressure valve w/ original and see what that does. One more thing to mention is the adjustment of the brake arm and push rod that actuate the pb and the mc. That pushrod dimension is super important for sure. Just my 2 cents.

[67428GT500]

It's all new. There is no adjustment on a 1967 Midland booster. The 1967 is a distribution block, not a proportioning valve. It has a simple shuttle valve that works as a safety in the advent of a front or rear leak out. The residual valve in the rear just maintains a slight amount of pressure at the rear drums.
The booster check is brand new, the booster is rebuilt, no leaks at any fittings. Every hose and line is new. The calipers are rebuilt, wheel cylinders are new and all hardware and adjusters. I did have to thin the Hawk pads out on a coarse piece of sandpaper because they were too thick by about .080.
 
                                                                                                 -Keith

[67xr7cat]

No experience with those pads, but some high performance brake pads don't brake well when cold. Beyond that you may want to drive another '67 to compare how yours brakes. A '67 just does not compare to modern stuff. Heck my 2002 Grand Marquis brakes better... lol

[67428GT500]

Well, my Saab nordic convertible I had shipped in has almost 14" brakes on the front and 12" on the back. It shuts down a 3900 lb convertible quite nicely.
I should still be able to lock the brakes up.

[67xr7cat]

Well stock front discs on a '67 are about 11". A GT500 is about 3400 lbs and likely more than that in reality.

[67428GT500]

I should be able to lock the wheels. It won't, not even the rear. I thought it may be the master. I replaced it with a quality non-imported unit.
I think I am going to pick up a set of pressure gauges and start there.

[67xr7cat]

Well locking up the tire don't know. Depends on how sticky your tires are, road surface, and how fast you are going.

I can tell you this, if the master is faulty it will leak and if you hold the pedal down it will fall away. It should stay firm. If you have the wrong brake pedal or master the pedal will have the wrong pedal travel, but you still will at some point generate the same pressure provided you have enough travel.

Your car should have a 1" bore MC, and the power brake pedal. Correct travel should be about an 1" to 1-1/2" and pedal should be firm. If the pedal is hard and you have to push hard to keep the car from rolling in gear then your booster is not working correctly.

The power brake set up has less leverage then the manual setup so your travel is less, but you need the booster to make it up. If their is air in the lines you will have a spongy pedal.

If it was me I'd start by trying a cheap set of brake pads and scuff the rotors see what that does. I would also verify that the caliper pistons move freely. Stuck or sticking caliper pistons is a common problem. I l know is all new, but is easy to verify.

[67428GT500]

I thought about something else. The brake hoses aren't U.S. made. I ran into an issue years ago that when the manufacturer crimped the hose they all but closed the hose off. The fact that the pistons are all the way in the bore and there was about .010 clearance. I also considered that there isn't enough room for fluid to apply enough pressure. I am good with brakes and have never had this kind of issue. At the end of the day it's going to be something so simple it's stupid.                                                                      -Keith