Members with 4 wheel disc systems: Can you lock up your brakes?

[Kern Dog]

Are you as confident in the brakes in your Charger as you are in your daily driver?
THAT is what I want. It is possible, too. My car is lighter than our Challenger so I have that going for me.

[Kern Dog]

HERE is the picture I wanted to post...

[Kern Dog]

That reduction linkage uses a short pushrod to connect the brake pedal arm to the reduction linkage under the dash. Where you see that orange arrow in the picture above, I was going to CUT and weld a small stub in between. I want the brake pedal the same height as the clutch pedal.
A guy on FBBO offered to modify a spare of his and send it to me. He made it adjustable with a threaded end. I roughly assumed that I only needed 1/4" more to have even pedals. I'd planned to mock mine all up before any welding of parts.

I'll send him a spare of mine so he isn't lacking any parts for future builds.





   

[Kern Dog]

The anticipation while waiting for parts to arrive is palpable.
Looking out the window from inside the house, looking across the yard when I'm out in the shop....Checking the mailbox 2-3 times a day thinking the mailman passed by when I wasn't looking....

[Kern Dog]

Still waiting.

[70 sublime]

I am following along

[Kern Dog]

I am writing about this partly to help others that may encounter the same thing.

Today was a bit frustrating but I think that I ended on a good note. I really don't like leaving the shop on a failed effort. The sting of that sticks with me and puts me in a bad mood that is hard to shake.

Today I pulled the iron 15/16" master cylinder and put in the aluminum 1 1/32" unit.




 

[Kern Dog]

The pedal feel at rest was good but the travel was short. That is to be expected since for every inch of travel, a master cylinder with a larger bore moves more fluid.
Out on the road, pedal feel was okay....not as good as with the 15/16" unit but acceptable. I wasn't sure that I wanted to go backwards in pedal feel though.
On the way home at stoplights, the pedal would sink to the floor. When moving, the pedal felt fine but at a stop, it sank. The system was bled out before I went for a drive so I thought that this master cylinder was bad.
Back at home, I swapped it out with this 2 bolt 15/16" unit I've had in the car since November:

[Kern Dog]

I bled out the system again and started it up to drive. I tested the pedal feel at rest and oddly, the pedal sank with this master cylinder too. I didn't see any leaks at the calipers. I had the wife press the pedal while I looked for leaks. Right there in plain view, I saw fluid dripping from the frontmost port on the master cylinder, the one that feeds the rear brakes. The fittings are old....circa mid 70s. I'll probably replace them when I redo the brake lines. For now, another 1/4 turn snugged them up enough to stop the leak.
I wanted to bring the brake pedal up a bit. The B body booster and linkage made the brake pedal sit about 1 1/4" lower than the clutch pedal. I had a buddy modify a spare pushrod....



 

[Kern Dog]

I used 4 washers to serve as spacers between the two halves and smeared Locktite on the threads.
Now the brake pedal is almost even with the clutch.








   

[70 sublime]

Makes my back feel sore just thinking how many times you have been up under the dash swapping things around 

[Kern Dog]

Ha ha...
I had the steering wheel off to get better access. It was still a bit uncomfortable.
I fell from my home roof 2 months ago and still have some discomfort in my arms and upper body from the fall so stuff like this is a bit of a struggle compared to before.

[Kern Dog]

***UPDATE***
I have found a combination that makes enough force to skid the tires.
No, it was not on wet pavement and not on oily roads!
This setup seems to be the BEST that I have had in all the years with the car. The pedal feel is great, pedal travel is not too long or too short, the stopping ability is fantastic and twice I got the front to skid. For some reason, the left seemed to want to skid more than the right. The front tires are ready to be replaced and I have a spare set so the possible "flat-spotting" of the tires isn't an issue.
I'm curious if there is any possibility that the side with the longest brake line could be the one most likely to get less or at least delayed pressure?
I know very little about hydraulic function so this is one of those things that have me curious.
Regardless.....
This is great news.
Now, I have to go back and REadjust the brake light switch. I did have it adjusted but it seems to have either moved a little or needed more attention.
SCORE !

[Kern Dog]

The brake switch has been adjusted and all seems well.
All these years with all the different combinations that I have tried, I wasn't sure why I was unable to get the brakes in this car to feel the way that I wanted.
I've had a few disc/drum Dusters and Darts both with and without power assist and they have stopped as good or better than new cars. Of course, I haven't driven a Corvette or Viper but I have driven new Challengers and other late model cars.
I had a disc/drum setup in the car until sometime in 2006. It stopped fine but the rear drum looked small through the spokes of the wheel. Yeah...I swapped in a 11.7" disc kit completely for appearance's sake.
By 2012, I had a cam with low vacuum and the power brakes were not good so I tried 4 different manual master cylinders. NONE of them felt right. None of them felt safe because even standing on the pedal, the brakes didn't react enough.
I have a manual MC in my "Jigsaw" Charger but it is disc/drum. the self energizing feature of drum brakes allows for lower brake pressures while still working well. Jigsaw stops quite well but not like a lighter Duster or Dart with the same arrangement.
Manual master cylinders with 4 wheel disc brakes has proven to be inadequate for me. I even tried again late last year with these new front brakes.
All along, what was required was the extra brake pressure that the dual diaphragm booster provides. I haven't tested the pressure with my gauges but I may later.
In short, the car feels like a late model. You gently press the brake, the car gently slows down. You press harder, the brakes bite harder. There is confidence that wasn't there before.
Imagine for a moment that you're driving a slant six 4wd truck.....a 4700 lb tank. You press the gas pedal halfway down to pass someone, then floor it with NO difference in the rate of acceleration between 1/2 and full throttle. That was what these brakes were like before. Harder foot pressure didn't give more bite.
All is good now though!

[Kern Dog]

As a testament to "natural proportioning", the car only skids the front tires. I was able to get both to skid on Saturday under a "jam on the brakes" effort.
There is no proportioning valve in the system, just a 4 wheel drum distribution block. The rears never skidded.

Rick Ehrenberg has written about "natural proportioning" and stated that it is the proper way to set up the car, that using a proportioning valve should be considered a "tuning aid". To me, I understood that to mean get the car set up right and you shouldn't need it.

The engine wants to stall under extreme braking. I thought I'd fixed that. Some say it is due to a high float level.
The Barry Grant Demon is similar to a Holley and has sight plugs in the float bowls. The fuel is just below center in both front and rear but maybe I'll lower the rear a little more and retest.