ONE thing to remember, on Chrysler product brakes, the brakes happen "at the top" of travel, not "1/2 way down" as similar GM vehicles usually were. That was when they were new or unmolested used cars. NO way should the pedal get anywhere near the floor during normal stopping actions. IF the pedal goes that low, then all four wheels should be locked up and the tires howling as you push yourself BACK from the steering wheel (even with a fully-tightened lap seat belt).
There is a really neat brake adjustment caliper you can get. Inside-Outside Brake Caliper. Set the outside diameter to the brake drum inner diameter, by feel. Then check how the Inside matches up with the brake linings, adjust as necessary. Put things back together and the adjustment should be "to specs". Beats the "through the slot" adjustment procedure by a good bit!
ALSO, the innards of drum brakes can and will accumulate brake lining dust, which decreases braking power. In the old days, we'd get them blown out with the shop air nozzle, dusting everything in the shop in the process. In later years, a stream of water focused between the backing plate and drum would seem to work as well. Either way, "hazardous materials" were released into "the world". Currently, some gentle spray brake cleaner, catching the run-off into absorbent towels, then properly disposing of these things, AFTER the brake cleaner evapoerates!, would be best.
Typically, the master cylinder pushrod should not be touched or re-adjusted, BUT I believe there might be a length spec in the service manual, somewhere? Allegedly, some cars' brake pedals had two pushrod attachments? One for manual brakes and one for power brakes.
Booster impending failures usually do NOT mean added pedal travel. Increased pedal pressure as the diaphragm starts to leak or the reaction valve fails. If an engine miss happens when the pedal is depressed, but stops when the pedal is released, that's the diaphram
The dual diaphragm booster will stick out more from the cowl it mounts to. The single diaphragm pb booster will be larger in diameter, but much thinner, which will need additional cowl mouting space around it to work, which the earlier models didn't have.
To me, the old power drum brakes had a much firmer/hard pedal feel when engaged. Push the pedal to stop, then while stopped, push more and you're usually only deflecting the brake pedal with the added effort. Power disc brakes, in the same stopped situation, seem to have a bit of sponginess to the added pedal pressure. Not sure why, but they did. On my '77 Camaro, it was claimed the master cyl was "bypassing", but the replacement ones did the same thing, so I stopped worrying about it. But that Camaro never did stop right, to me.
After I put the COPO 9C1 Nova police car front pads and 11x2 '81 Z/28 Export rear brakes on it, did it stop to "stop like a Chrysler", which made me happy. The front pads were OEM on Cadillac limos and Livery cars. The rear brakes were '77 MonteCarlo normal production, plus '80s Caprice police cars. All bolt-in stuff for the Camaro.
Enjoy!
CBODY67
