I put front disc brakes on my AD years ago and engineered it to use a firewall mounted MC/vacuum/power booster. Initially I did supply vacuum to it but the brakes were wayyyyy too sensitive. I had the thought to try it without the vacuum assist and was somewhat surprised to find that the brakes felt/behaved just fine without vacuum….just takes a little more muscle. I left the booster in place…with no vacuum connection. Been driving it that way for about 10 years. (“Real men” don’t need power brakes….or automatic transmissions….or fuel injection…or air conditioning, or etc etc….I’m joking….)
Phak1, try it without the vacuum?
Regards, Dave