Weak brakes on new disc/disc setup

[GregWeld]

Switchblade --

The other possible thing to look at is your pedal ratio on the brake. We don't know what the car came with in '55... manual or power... and the pedal ratio is important as it's a multiplier of the power you apply with your foot.

It should be 6:1 for manual and 4:1 for power brakes.

Also --- As Tobin pointed out -- the Master is CRITICAL.... larger bores make LESS pressure -- smaller bores make MORE pressure.

There are diagnostic tools for pressure measurement at the calipers. Don't guess - invest in these relatively cheap pressure measuring tools - or find a competent shop that can take these measurements.