Packard Forum Index » Modification Discussion

They could be original and still be power disc brakes. The Treadlevac is different than modern power disc brakes, you wouldn't see the big canister on top. The pedal would usually say "Easamatic" but it could have been replaced. The pedal operates from a pivot above the pedal, and pushes straight into the treadlevac behind the toe plate. If it's manual brakes, then IIRC the pedal is pivoted from the floor, and the master cylinder is under the floor.

One thing that could be true is you could have poor vacuum or a restricted vacuum line, or something else with the vacuum system feeding the brakes, such that the initial push uses up the reserve vacuum in the tank under the fender, but because of the restriction you cannot adequately provide vacuum afterwards.