RedHot67 -
Sorry to hear about all of the troubles you're having with getting your brake system to work well, especially from all the way over in Germany. You sound like me 3 yrs ago! I too fell for marketing hype and wasted my money and thought for sure these pre-boxed brake kits MUST be better than what I had since it's the 21st century. WRONG! I have a '68 Plymouth Sport Satellite. It came with stock rear drums (leave 'em, they're fine) and the previous owner had already converted the fronts to disc spindle, calipers, master cylinder and single diaphragm vacuum booster from an early '70's A-body or E-body he told me. Those brakes grabbed hard! They were snappy, but no proportioning valve, only the distribution valve, so they were probably dangerous, but could be made to work with a proportioning valve installed. Problem was that when applying the brake, the front end pulled hard left. I thought the rotors or calipers were bad, but didn't discover it was only a plugged brake line until after I'd already sold the brakes and bought a kit in a box from Master Power Brakes. I am not new to classic cars, but was new to mopars at the time and didn't know jack. What I learned - DO NOT SELL PARTS YOU REMOVE UNTIL YOU ARE HAPPY WITH THE REPLACEMENT PARTS. haha If I had to do it over again, I'd leave the '70's E-body or A-body setup that was on there. I know others have this setup and are very happy with it.
So fast forward - I bought the full kit from MPB like you bought the SSBC kit, mainly because MPB supplies stock disc spindles from a Cordoba (someone else mentioned that adaptability earlier). After installed, I HATED the way the pedal felt and braking was sub-par. My mechanic showed me how the slider calipers were bent and not sliding freely and true, but he managed to beat them into shape and even with a master cylinder change I still hated them. I did, however, really like Master Power Brake's customer service and I only wish they're kit was just as good.
What I have now and really like are stock 10" rear drums, 11.75" x 1" thick flat rotors from Napa Auto (generic stuff, but 1" bigger than stock diameter and no need for cross-drilled slotted rotors - no need for the street and they take a long time to wear in so the pedal doesn't feel funny.). I also have a caliper adapter from AR engineering to accept the larger rotors, wilwood forged dynalite 4-piston pin-type calipers with wilwood BP-10 pads, wilwood proportioning valve, and a Raybestos brand Blue box (their mid-grade and recommended over the cheaper one due to casting quality and lid sealing) master cylinder with 15/16" bore, along with some pretty high end stainless steel brake lines with real nice fittings to prevent leaks that my suspension shop sourced for me from one of their go-to vendors. The brake lines were key as was the MC bore being close to 1". Go too much bigger and pedal may feel too soft, but I guess that depends on your caliper demand. Only thing I kept from MPB was their 8" dual diaphragm vacuum booster. Pedal feel is great, not too snappy, but don't have to stand on it to get it to stop. This setup works really well.
If I were you I'd ditch those calipers and Master Cylinder and brake lines and make sure you use a Master Cylinder for Disc/drum if that's what you have, along with the proportioning valve.
My experience with Summit Racing - one of my top 2 go-to suppliers for standard name-brand stuff (milodon, Lunati, Melling, Cloyes). Always VERY satisfied with Summit's customer service, super fast deliveries, and best of all - if something needs returned, they ALWAYS accept it back with a full refund and no questions asked. Tough to find that nowadays.
Good luck with your project and sorry for the novel!
