power brakes
- Thread starter JD poly
- Start date
It's not challenging - one should swap out the pedal assembly too because the leverage ratio for a manual pedal assembly is much greater, however I have heard that it's just fine using a manual pedal with a booster.
I have no personal experience with the retrofit, but everything if sourced correctly will simply bolt up.
I have no personal experience with the retrofit, but everything if sourced correctly will simply bolt up.
The correct booster would be a Midland Ross unit. That is the one with the lock ring around the outside. If your salvage yard has one, grab the mounting plate and the pedal while you are at it. You can use the '67 master cylinder which will bolt on the '66 mount plate. You will also need to source the '67 distribution block and fabricate the brake lines from the master cylinder to the distribution block. You would also want to have the salvage yard booster rebuilt.
Dave
Last edited:
- Joined
- Jul 24, 2011
- Messages
- 1,546
- Reaction score
- 1,810
X 2 on what Davea ^^^ indicated ^^^ —- all of that has to be salvage yard ONLY —-
Because the ONLY thing on that list that is available N E W is the Dual Master Cylinder…..
Because the ONLY thing on that list that is available N E W is the Dual Master Cylinder…..
volksworld
Well-Known Member
Stephens Performance has a Mopar salvage yard in Alabama...you may be able to source what you need there
volksworld
Well-Known Member
The back plate and pedal assembly are different...here you can see the 4 holes where the booster bolts on
Correct - I neglected to say that there is a backing plate that will be part of the swap - one should get that plate as well as the power brake pedal assembly.
Sixpactogo
Well-Known Member
I removed a Power brake booster, backing plate and underdash linkage from a 66 Chrysler Newport that I parted out and swapped it in my 65 Sport Fury. I bought a new dual bowl master for a 72 or newer C body drum brakes and made new lines myself. Easy Peasy. It has been working great for the past 20 years or more.
Note: I was able to test the booster before I removed it and it was working fine. If you cannot test it, you may want to have it rebuilt before installing it.
If you decide to upgrade to front disc's, you need to upgrade to a dual diaphragm booster since disc's require twice as much boost as do the drums.
Note: I was able to test the booster before I removed it and it was working fine. If you cannot test it, you may want to have it rebuilt before installing it.
If you decide to upgrade to front disc's, you need to upgrade to a dual diaphragm booster since disc's require twice as much boost as do the drums.
volksworld
Well-Known Member
not to overly complicate your search but I've been running a single diaphram Midland (drum) booster with discs for over 20 years
Sixpactogo
Well-Known Member
Is it a 10" single diaphragm? From my research, a single 8" booster will provide 402 lbs of force. Enough for drum brakes. With disc brakes requiring almost double, a single 10" booster would provide 785 lbs of force. Probably enough for discs.
volksworld
Well-Known Member
its a 9 1/2...its kinda an apples and oranges deal....original budd style discs on slabsides used 4 piston calipers, a larger diameter master (1 1/8) for the extra volume and a dual diaphragm for the extra force to push it....the 71/73 single piston calipers used a smaller diameter master (1 1/32) and it seems that you can get away with the single diaphragm booster....it's not a "touch it and your head hits the windshield", it just feels like modern power brakes...no, I've never done the math on the amount of fluid moved by the early vs late system....the drum brake dual master would be a 1 inch bore....on a manual pedal the distance from where the pedal pivots to where the rod to the master attaches is a little over 2 inches...on a power pedal its about 6 inches, so the leverage is completely different
Last edited:
Sixpactogo
Well-Known Member
I'm sure the factory did their due diligence when they developed your system. According to the formula designed for power assisted brakes, your booster creates 673 lbs of pressure. The master cylinder also has a formula but I don't have that handy. Apparently the 9.5 single is sufficient with your combination.
My research on boosters was due to when I upgraded my 68 Charger from drum to front discs. I used the stock single 8" booster and found the stopping power was not near as good as it was with the drums. When I found the formula the designers use, it made sense as to why my brakes were Piss Poor.
They take the booster diameter and divide by 2 and times that by itself X 3.14 and times that by the actual diameter of the diaphragm to get the force it will apply.
In your case a 9.5 single diaphragm the formula is 4.7 X 4.75 X3.14 = 70.84 X 9.5 = 673 lbs of pressure
In my case my single 8" diaphragm which came out to 4 X4X3.14 =50.24 X 8 =401.9 lbs of pressure
The article went on to say that drum brakes require about 400 lbs of force to lock them up while discs require almost 800 lbs.
that is why when they began putting front discs on my Charger. the started using an 8" dual diaphragm booster since it doubles the pressure to 803.
When I upgraded to the dual 8" unit my brakes are perfect.
300George
Member
Contact Murray Park for any stuff you'll need
traintech55
Senior Member
I did this conversion on my 1966 300. Order the brake lines and distribution block from Inline tube for a 1967. Everything bolts right in.
Just Carbs
Senior Member
I have a 64 new Yorker. Single pot master power drum brakes.
Changed the master to a 67 dual pot drum brake master.
Then later swapped the front drum brakes to 79 Cordoba 11.75 disc and 79 Cordoba single piston calipers.
Didn't change the drum dual master to disc dual master. Still using the 64 booster. Don't know the 64-booster size.
Was necessary to install smaller diameter rear drum cylinders. No proportioning valve, not needed on "this" car with the smaller rear cylinders.
Plenty of boost on "this" car.
Changing to the larger piston disc dual master might reduce stopping power.
Haven't driven enough to add fluid to the reduced capacity drum dual master yet. No plans to change to the disc dual master. We'll see.
The car stops very good. Love the pedal modulation. Very happy.
Thrilled actually.
Changed the master to a 67 dual pot drum brake master.
Then later swapped the front drum brakes to 79 Cordoba 11.75 disc and 79 Cordoba single piston calipers.
Didn't change the drum dual master to disc dual master. Still using the 64 booster. Don't know the 64-booster size.
Was necessary to install smaller diameter rear drum cylinders. No proportioning valve, not needed on "this" car with the smaller rear cylinders.
Plenty of boost on "this" car.
Changing to the larger piston disc dual master might reduce stopping power.
Haven't driven enough to add fluid to the reduced capacity drum dual master yet. No plans to change to the disc dual master. We'll see.
The car stops very good. Love the pedal modulation. Very happy.
Thrilled actually.
Sixpactogo
Well-Known Member
If your combination of miss matched parts work for you, you are very lucky IMO. There are way too many threads on these sites describing the nightmare of brake issues from doing pretty much what you did. The factory did a ton of research while engineering these cars and their equipment. Disc brakes require more fluid and more pressure to be effective. At the very least, I hope you check your master often to be sure it is not low on fluid. Brakes are way to important to cut corners on.
Last edited:
Just Carbs
Senior Member
I appreciate your concern.
I was aware that the drum booster might not provide desired power assist and that the drum master cylinder reservoir volume might not be compatible with the disc brakes.
But my biggest concern was the master cylinder piston travel not providing enough volume under all conditions before bottoming out.
So, we started the car and applied a LOT of pressure to the brake pedal. Then opened the line to the disc brakes under those conditions. The pedal travel with the line closed before opening the line is about a third of the total travel with the line opened.
The disc conversion has only 8k miles on it, so not enough to show a detectable drop in fluid level from pad wear yet. I did check it very often. Not as often now.
Pedal modulation is excellent. Boost is ideal. I think I could go from this 1.0 diameter drum piston to the available 1.25 disc piston and still have plenty of boost. Definitely should try, probably will.
I will say that in spite of the fine 413 engine, 727 trans, suspension and steering, that the brakes are now the best part of the car.
I mentioned this conversion only because "this" 64 power "drum" booster works well with "this" power disc conversion on "this" car.
I suspect that a lot of the factory engineering was a result of how Chrysler "thought" the average buyer wanted the brakes to feel, and not just how well it works. Or we might not even have boosters.
Similar threads
