I have been researching brake issues as well as reading up in the maintenance manual for my '68 big block car but kind of stuck about what my next move should be. My brakes work marginally with new pads/shoes but I only get a season of driving before I lose confidence in them. They have never worked well enough to lock up on dry roads.
The brake pads have plenty of material and the rotors are 0.9" thick. I think the minimum is 0.8"? I have also replaced the brake fluid and bled them plenty. Coming out for the season I can already put the pedal to the floor after maybe 3000 miles of easy driving last year.
I performed the brake pedal to floor measurement and it’s low. 5" to 5.1" but the range is 5.33" to 6.2". Can I adjust the brake booster rod from the interior of the vehicle? The pedal has the safety stop to prevent pulling on the rod. However I bet there 0.75" gap before it would hit the stop. I have a teardrop shapped rod but with a newer style rubber cover.
I have the Midland style booster. No spacer on the firewall and correct looking spacer between master cylinder and booster. I seem to have lost a lot of pedal travel but unsure where/how to compensate for it. Taking the booster out for adjustment etc… is going to be a chore given the chewed up nut that’s up in there.
Note - The brake fluid on the master cylinder is from a spill over what I checked the level. Fluid is full and clear.
I think the blue arrow pointing to what you think is a “chewed up nut” is just the back end of the bolt that you can see at the top right of your first photo. It holds the booster in place from the engine compartment side along with the other nuts that attach to the booster studs on the passenger compartment side.
It’s not that bad, just take Royce’s advice and pull the steering column (and the driver’s seat) to do it.
Read your shop manual it tells you exactly how to tell if your power booster is working properly. Your first pic looks to have two nuts on the bottom booster stud and you were right the top welded on nut looks to be well abused for something that doesnt get removed. Also what you point to as a safety stop is a mounting bracket for a cruse control switch which from your pics your car doesnt have.
Figured I’d update this old post with a better view of the booster now that it’s out. Plan is to send it out to get rebuilt and freshened up. Whoever what at it last time marked it with three circles in green on the back and three red dots on the front. I’m also admiring the bent screw. Safety First!
No idea on the marks but that is a Midland booster that was used from 1967 - 69 and it is the best one you can have. It’s a dual diaphragm and far better than the Bendix unit that replaced it.
And I recently bought one of the reproduction units from WCCC and it works very well. You may get it faster, pay about he same and still have your core.
