My '57 2 ton has hydraulic brakes with HydroVac, the booster is frame mounted and divorced from the master cylinder, this is the stock configuration. Currently the brake pedal goes to the floor upon the first push, if I pump it several times it will build pressure and hold a good high and firm pedal. The scenario is the same with the truck running or with no vacuum applied and therefore I do not think the problem is HydroVac related. I adjusted all 4 brakes to obtain a pretty stiff rubbing, no change in the pedal, also the master cylinder was not low on fluid and the hard lines and all rubber were new along with all cylinders rebuilt 8 years ago. I don't want to pull the drums due to the hubs and drums are hard to separate and I would be into wheel bearings, so I want to start with what I think is the master cylinder giving me problems. If the collective minds here think I'm full of bovine manure, then tell me. If you have some suggestions on how to diagnose further, I will try those also. Thank you in advance.
Last edited by 78buckshot; 05/07/2026 1:27 AM.
