I have manual discs using spindles and discs from a 73 plymouth and a proportioning valve from a manual disc brake dart sport from the early 70's. manual discs and they work great.

Hey timinator, any updates? Did you get this issue resolved? I just did the same conversion on my 68 Charger and have the exact same problem. Wondering if more aggresive brake pads made a difference.

An old thread but I seem to have a similar problem - did the discotech conversion using

10.87 rotors
72 Ebody calipers
1 1/32 master
all new lines and hoses

No proportioning valve at all....

10*1.75 drums out back of a 69 Plymouth Belvedere.

Not a super firm pedal, car stops but can't lock up anything, felt better with the manual drums!

Where should I start?

Plazomat

15/16" master cylinder. Then you will likely need an adjustable proportioning valve or a factory B body one off a disc brake car.

Kevin

I hope I don't come across wrong but I've read many threads with this complaint. Why do so many people ignore these bad results threads and spring for the aftermarket stuff? There are also many folks that use the factory Mopar parts to adapt their cars and have great results. And a lot of that stuff is available in junkyards and local parts stores. I don't get it.