Brake Swap Master Cylinder

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jar84203

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If converting 71 Duster front drum brakes to 73 disc, does the master cylinder need to be swapped too? Thanks.
 
Each company will have a different part number, just order one for a 73, they all bolt up the same and will inter change. Just needs to be for disc brakes.
 
1973 DODGE DART SPORT 340 5.6L 340cid V8 (H) : Brake/Wheel Hub : Master Cylinder Price Core Total Advice
A-1 CARDONE Part # 101571 More Info {Reman.}
w/Disc Brakes w/Power Brakes

Part Image
$21.79 $3.00 $24.79
Add to Cart
A-1 CARDONE Part # 101516M More Info {Reman.}
w/Drum Brakes w/Manual Brakes w/9" Rear Brakes

Part Image
$21.79 $5.00 $26.79
Add to Cart
A-1 CARDONE Part # 101627 More Info {Reman.}
w/Disc Brakes w/Manual Brakes

Part Image
$22.79 $10.00 $32.79
Add to Cart
A-1 CARDONE Part # 101573 More Info {Reman.}
w/Drum Brakes w/Power Brakes w/10" Rear Brakes

Part Image
$25.79 $8.00 $33.79
Add to Cart
DORMAN Part # M79772 More Info {First Stop #3580027, 5474196}
w/Manual Drum Brakes; Bore = 15/16"; 9' Brakes

Part Image
$49.79 $0.00 $49.79
Add to Cart
RAYBESTOS Part # MC36406 More Info {Professional Grade; Bore Size=15/16" Number of Ports=2 Primary Outlet Size=9/16x20 Secondary Outlet Size=1/2x20}
Front Disc Brakes; Rear Drum Brakes; Power Brakes

Part Image
$64.79 $0.00 $64.79
Add to Cart
RAYBESTOS Part # MC36412 More Info {Professional Grade; Bore Size=1 1/32" Number of Ports=2 Primary Outlet Size=9/16x20 Secondary Outlet Size=1/2x20}
Front Disc Brakes; Rear Drum Brakes; Manual Brakes

Part Image
$65.79 $0.00 $65.79
Add to Cart
RAYBESTOS Part # MC36338 More Info {Professional Grade; Bore Size=15/16" Number of Ports=2 Primary Outlet Size=9/16x20 Secondary Outlet Size=1/2x20}
Front Drum Brakes; Rear Drum Brakes; Manual Brakes; 9" Brakes

Part Image
$65.79 $0.00 $65.79
Add to Cart
RAYBESTOS Part # MC36439 More Info {Professional Grade; Bore Size=1 1/32" Number of Ports=2 Primary Outlet Size=9/16x20 Secondary Outlet Size=1/2x20}
Front Drum Brakes; Rear Drum Brakes; Manual Brakes; 10" Brakes

Part Image
$68.79 $0.00 $68.79
Add to Cart
ACDELCO Part # 18M34 More Info {#18030276}
CYLINDER,BRK MAS DURASTOP; 31/32IN CYL BORE; w/o POWER BRAKES
* Non-stock item--shipping delayed up to 5 business days

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$72.79 $0.00 $72.79
Add to Cart
ACDELCO Part # 18M1064 More Info {#19106850}
CYLINDER,BRK MAS DURASTOP; w/FRONT DRUM BRAKES or REAR DRUM BRAKES or MANUAL BRAKES; 10IN BRKS
* Non-stock item--shipping delayed up to 5 business days

Part Image
$81.79 $0.00 $81.79
Add to Cart
ACDELCO Part # 18M1053 More Info {#19106839}
CYLINDER,BRK MAS DURASTOP; 9IN BRKS
* Non-stock item--shipping delayed up to 5 business days

Part Image
$81.79 $0.00 $81.79
Add to Cart
ACDELCO Part # 18M1060 More Info {#19106846}
CYLINDER,BRK MAS DURASTOP
* Non-stock item--shipping delayed up to 5 business days

Part Image
$83.79 $0.00 $83.79
Add to Cart
 
That's a cut and paste from Rockauto.com I'm too lazy to edit it this am!!
 
If you don't like the prospect of having a rock hard pedal with no travel, try a manual disc brake master cylinder from a 1974 Charger. That's what I used on my '66 Valiant, and wouldn't have any other setup. 8)
 
grumpuscreature said:
If you don't like the prospect of having a rock hard pedal with no travel, try a manual disc brake master cylinder from a 1974 Charger. That's what I used on my '66 Valiant, and wouldn't have any other setup. 8)
Click to expand...

Mine is manual brakes. I used a M/C from an 85 Dodge truck (1 1/8" bore) with front disc off of a 73 Dart, an adjustable prop valve and 11" Ford drums on the rear and the pedal feels good, not too hard and stops on a dime.

I was expecting it to be rock hard but it's not.
 
I am looking to change out my manual brakes for power brakes, my 1971 duster does not stop very well, do I only need get master cylinder and a power boster/bracket to make the car stop better? I dont really care if the car will stilll have the front drums as long as I can stop on a dime instead of rolling through the stop lights. Any advise is welcomed.
 
Power brakes won't make the vehicle stop better, it'll just decrease pedal effort. You should think about installing front disc brakes on the fronts, maybe even rear if you want the best stopping power.
 
If this is the case, then what is the best way to do this convertion to disks.
I have heard that it is hard to find parts for the small bolt pattern for the front end, if I go to the large bolt patter on the front end what about the rear end?
 
I am looking to change out my manual brakes for power brakes, my 1971 duster does not stop very well, do I only need get master cylinder and a power boster/bracket to make the car stop better? I dont really care if the car will stilll have the front drums as long as I can stop on a dime instead of rolling through the stop lights. Any info is welcomed.
 
There are many different routes you can go. You can swap on later A body disc brakes for the front and different axles for the rear or you can purchase an aftermarket disc brake conversion kit. Some companies to look into include Master Power Brakes, Stainless Steel Brakes, and Wilwood. I have not used any of them so I wouldn't know how good the kits are.
 
easy swap,
get some '73+ spindles or FMJ and some '76+ A, FMJ calipers, then a '73-'74 A body master with power brakes and then you will have large boar calipers with small boar master. The result is a nice firm pedal that stops the car very nicely. Make sure to use the proper prop valve as well, either the FMJ one or '73+ A body disk brake one. I also recommend an adjustable valve for the rear so you can get them to lock when you want.
 
res1vw21 said:
'73-'74 A body master with power brakes and then you will have large boar calipers with small boar master. The result is a nice firm pedal that stops the car very nicely.
Click to expand...


You want a larger bore master cylinder, not a small bore. The Larger bore gives you quicker response when braking with less pedal travel.


Also with the 73-76 Dart disc and the Valarie disc conversion, you also need the 73-76 Dart upper control arms with the larger ball joint.
 
Pascal's law - "a change in the pressure of an enclosed incompressible fluid is conveyed undiminished to every part of the fluid and to the surfaces of its container."

http://www.grc.nasa.gov/WWW/K-12/Wi...hyperphysics.phy-astr.gsu.edu/HBASE/pasc.html

http://en.wikipedia.org/wiki/Hydraulic_brake - A larger diameter master cylinder delivers more hydraulic fluid to the caliper pistons, yet requires more brake pedal force and less brake pedal stroke to achieve a given deceleration. A smaller diameter master cylinder has the opposite effect.

http://hyperphysics.phy-astr.gsu.edu/HBASE/pasc.html#hpcal- 3rd one down - an online calculator, you can plug in some numbers and see that by increasing the MC piston size you loose your force multiplication resulting in more force needed, with a little less distance to accomplish the same goal. IE a little less pedal travel with greater force needed to get the pistons in the calipers to move the same distance. Simply put you have to push harder.

another example
http://science.howstuffworks.com/hydraulic1.htm


To determine the multiplication factor, start by looking at the size of the pistons. Assume that the piston on the left is 2 inches in diameter (1-inch radius), while the piston on the right is 6 inches in diameter (3-inch radius). The area of the two pistons is Pi * r2. The area of the left piston is therefore 3.14, while the area of the piston on the right is 28.26. The piston on the right is 9 times larger than the piston on the left. What that means is that any force applied to the left-hand piston will appear 9 times greater on the right-hand piston. So if you apply a 100-pound downward force to the left piston, a 900-pound upward force will appear on the right.

How brake fluid works

Pressure is the result of a force applied over a specific area and that pressure is therefore measured by the formula P = F / A or "pressure equals force divided by area". When a force is applied to an incompressible fluid, the area in question is the contact area between any two molecules of the fluid. That area is the same for any pair of molecules within the fluid. Because an incompressible fluid accepts and applies forces evenly throughout itself, the pressure will be equal at all points within the fluid. The molecules that are in contact with the surface of the container will push against that surface with the same pressure as between any two molecules anywhere else within the container because they have the same contact area with the molecules of the container as with each other.
If we consider that this container and its fluid contents are subject to gravity as an additional force then we must consider that the difference of pressure due to a difference in elevation within a fluid column is given by:

where
ΔP is the hydrostatic pressure (given in pascals in the SI system), or the difference in pressure at two points within a fluid column, due to the weight of the fluid;
ρ is the fluid density (in kilograms per cubic meter in the SI system);
g is acceleration due to gravity (normally using the sea level acceleration due to Earth's gravity in meters per second squared);
Δh is the height of fluid above the point of measurement, or the difference in elevation between the two points within the fluid column (in meters in SI).
The intuitive explanation of this formula is that the change in pressure between two elevations is due to the weight of the fluid between the elevations.
Note that the variation with height does not depend on any additional pressures. Therefore Pascal's law can be interpreted as saying that any change in pressure applied at any given point of the fluid is transmitted undiminished throughout the fluid.


In conclusion a small bore MC will require a little bit more pedal BUT the force multiplication goes up so it will be easier to stop with more power. A large bore MC will require a little less pedal travel but at the expense of more effort to push the pedal.

Having this set up on my car I highly recommend it and it doesn't seam like I have to push the pedal in very far to stop.






Blownfish said:
Also with the 73-76 Dart disc and the Valarie disc conversion, you also need the 73-76 Dart upper control arms with the larger ball joint.
Click to expand...
And you are correct
 
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