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Now that I have your attention, yes they are cheap brakes, and they are big brakes, but they are not brakes with 13" rotors. Still interested, read on. What we have here is a simple, easy disc brake upgrade for you Mustang, Falcon, Fairlane, Ranchero, etc. It will work on any intermediate Ford V-8 drum brake spindle from about '63-'73. It uses two fabricated caliper brackets, two 11" Granada rotors, and here is the big part- two big GM calipers that have the 2 15/16" piston.

-Why the big GM calipers?

Unlike most disk brake swaps tha use the small GM metric calipers, this swap uses the same calipers that would have stopped a big Impala or even some 1/2 ton pickups. The "metric" calipers that alot of swaps use have a 2 1/2" piston, but the big GM calipers have a 2 15/16" piston that offers 12% more clamping force. The big calipers also use a brake pad with a bigger friction surface. The big GM calipers are also more rigid and will flex far less that the metric calipers.

There are three ways to increase braking force:

1. Increase rotor swept area via a larger diameter rotor.
2. Increase piston diameter or number of pistons for more clamping force.
3. Increase brake pad surface area.

We have two of the three covered, and I can tell you that this same system was in use on the front of my IMCA dirt modified for several seasons and and it will out stop a metric caliper system.

The rotors are common '75-'80 Ford Granada or Mercury Monarch. There were bought new at O'Reillys for $49.99 each:


The calipers are '75 Impala items that were $14.99 each at O'Reilly's. The brake pads cost $14.99 and were bought at AutoZone:


Here is a comparison between the metric and big GM brake pads, the metrics are on top:


We also used six 2" long x 3/8"-24 fine thread grade 8 bolts with steel locknuts to hold the caliper brackets to the spindles. The brake caliper bolts come with the new calipers. Cost $3.24:


Here are the 3/16" inverted flare to #4 adapter fittings that will allow the use of two 18" long stainless steel braided hoses. The adapter fitting connects to the stock brake line and fits in the stock bracket. Cost $9.99 a pair for the fittings and $9.99 a piece for the hoses:


We also used two 7/16"-20 to #4 banjo fittings that will allow the hose to connect to the caliper. Cost $6.99 each:


The brackets started out as common circle track weld on brackets that allow the big GM calipers on the rear ends of race cars. Cost $8.00 a piece:


The bottom of the brackets are cut off, and two holes are drilled to allow it to bolt to the spindle:



Six 3/4" O.D. x 7/8" long spacers are needed to space the brackets out. The spacers fit between the brackets and the spindle. A small "dog leg" brace is also needed to allow it to bolt to a third spindle hole:


Everything is bolted to the spindle and the dog leg brace is welded to the main caliper bracket between the arrows. Sharp viewers will notice that the brackets are in front of the rotors. The calipers are flipped backwards and swapped side for side on this system. Meaning the left caliper is on the right side and the right caliper is on the left side:


Here are the finished brackets:



The drum, hub and backing plate will need to be removed:


Clean any burrs off the spindle around the holes:


The brackets are bolted on using the grade 8 bolts:


The rotors are bolted on using new bearings and seals. I re-used the original '66 Falcon bearings as they were new and had zero miles on them:


Here is a shot of the brackets bolted on from behind:


The calipers are bolted on and the hoses are hooked up:






Here is a break down for the cost:

-Granada rotors-$49.99 x 2 = $99.98
-Big GM calipers-$14.99 x 2 = $29.98
-Brake pads- $14.99
-Brake adapter fittings - $9.99
-Caliper banjo fittings- $6.99 x 2 = $13.98
-#4 stainless steel braided lines- $9.99 x 2 =$19.98
-Brake caliper brackets- $8.00 x 2 = $16.00

-Total cost = $208.14.

I did machine my own spacers, and make the small dog leg brace, and that would add slightly to the cost to have someone do it for you, but it would still come in at far less than $300.00, and you end up with awesome stopping power. I also need to add that these calipers will clear 14" disc brake steel or aluminum wheels. I omitted the master cylinder installation as there are plenty of articles covering that sort of information, but I will tell you that I used a non power '75 Maverick M/C with a 15/16" bore and no proportioning valve of any kind. It stops awesome.


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Last edited by F15Falcon; 12-02-2009 at 04:27 AM.
 

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Very nice ! Can this setup be used on a 69 Mach that came with PDB? I think the spindle is different.
Can you add where you sourced the caliper bracket from and part # ?
 

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I disagree with your #2 way above.

The pressure of the system is applied by the master cylinder and the load applied to the master cylinder. If you're using the same master cylinder and the same pedal force, then you are applying the exact same hydraulic pressure to the system.

and Pressure = Force / Area

So by increasing the Area of the calipers, you're actually decreasing the point force.

The gain is coming from the increased areas of the pad and rotor.

Nonetheless, this is a great write up. A job well done!
 

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IMHO when something like this, technical and safety related we need to know something about the source...who are you?
 

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I disagree with your #2 way above.

The pressure of the system is applied by the master cylinder and the load applied to the master cylinder. If you're using the same master cylinder and the same pedal force, then you are applying the exact same hydraulic pressure to the system.

and Pressure = Force / Area

So by increasing the Area of the calipers, you're actually decreasing the point force.

The gain is coming from the increased areas of the pad and rotor.

Nonetheless, this is a great write up. A job well done!
Brake Hydraulics

Basic hydraulic theory states that 1) liquids are incompressible and 2) the pressure of a given closed system is the same anywhere within the system.

Pressure[P] (psi) is force [F] (lbs) over area[A] (square inches). If a 1 inch diameter piston is depressed with a force of 150lbs, this will generate a pressure of (150/3.14*.5*.5) = 190.98 psi. If a hose is connected to another piston that has a 0.5" diameter piston we will see some force multiplication. The force would be the pressure multiplied by the piston area. (190.98psi*.25*.25*3.14)=37.50 lbs. So we see that a smaller piston will generate a smaller force given the same pressure.

Understanding brake torque

Brake torque is what stops the wheels. The brake torque (ft-lbs) of a wheel is the clamping force (lbs) of the caliper times the disk radius (ft), times the coefficient of friction for the brake pad. The disk radius is measured to the centre of the brake pad.

Clamping force (lbs) is the brake line pressure (psi) times the total piston area of the caliper (square inches). The total piston area of a fixed caliper is the total of all the pistons areas. In a sliding caliper, the total piston area is the total of all the pistons times 2.

The brake line pressure (psi) is calculated from the force applied at the pedal. The pedal force (lbs) is multiplied by the pedal ratio, and divided by the master cylinder piston area (square inches).



source: VdubEngineering - Brake Details
 

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Discussion Starter #6 (Edited)
IMHO when something like this, technical and safety related we need to know something about the source...who are you?
I was the Tech Editor for Fordmuscle.com for about 5 years. I own and operate my own fabrication shop where I build race cars and street rods. I also build suspension and chassis parts (roller spring perches, spring compressors, subframe connectors and roll bars) for Mustangs and Falcons that I sell online. I build alot of 9" rear end housings of all sorts. I am ASE certified in engine repair, brakes, and differentials. I am certified in TIG, MIG and oxy acetalene welding. I am a journeyman machinist and I have a Bachelors degree in History. I teach part time at our local community college.

Oh yeah, I have also done 19 tech articles on the VMF over the past year.
 

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I was the Tech Editor for Fordmuscle.com for about 5 years. I own and operate my own fabrication shop where I build race cars and street rods. I also build suspension and chassis parts (roller spring perches, spring compressors, subframe connectors and roll bars) for Mustangs and Falcons that I sell online. I build alot of 9" rear end housings of all sorts. I am ASE certified in engine repair, brakes, and differentials. I am certified in TIG, MIG and oxy acetalene welding. I am a journeyman machinist and I have a Bachelors degree in History. I teach part time at out local community college.
But more importantly, what is your horoscope sign?
 

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Definitely cheap. About what I have in my '99 Mustang/Granada brakes. I cheated and got the calipers, brackets, hoses, and a bit of brake line from a junkyard Mustang that had 6000 miles on it. It would surely be a quite a bit more if I had to buy that stuff new.
 

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I was the Tech Editor for Fordmuscle.com for about 5 years. I own and operate my own fabrication shop where I build race cars and street rods. I also build suspension and chassis parts (roller spring perches, spring compressors, subframe connectors and roll bars) for Mustangs and Falcons that I sell online. I build alot of 9" rear end housings of all sorts. I am ASE certified in engine repair, brakes, and differentials. I am certified in TIG, MIG and oxy acetalene welding. I am a journeyman machinist and I have a Bachelors degree in History. I teach part time at out local community college.
Hmmm...I'm still not convinced, lol.

Seriously though, thanks for the write up. Very cool.
 

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You're right. P = F/A So when Area increases Force increases to maintain the same pressure.

Then it becomes a question of fluid flow. The bigger pistons require more fluid flow to maintain the same pressure.
 

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You will still get the same pressure in the system, and the pressure is distributed over a larger area, thus more clamping action.

But, you can't get something for nothing, so what changes on the input side to make it that way?

Answer is you just give up a little stroke on the pedal. In other words, you have to push the pedal with the same force, but you have to push it FARTHER to move more fluid.

Looks good if you need a set that fits inside smaller wheels.
 

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Nice write up, wish I knew how to weld, stuff like this would be a lot easier..
Jon
 

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As long as you get the hydraulic ratios right, it looks like a good setup and for those who care it should fit under 15in wheels. That 2 15/16in piston is larger than typical Ford practice and I think something more like a 1 1/8in MC would be preferable, I can't imagine I'd be happy with the pedal travel with a 15/16 MC. . Not sure how well they'd balance with something like the Cobra rear caliper with its tiny pistons. D52 pad availability is very good in just about every kind of compound you could want.

Some circle-track vendors do an aluminum version of that caliper, cost more of course but take off significant weight.

Now that you've got the bracket sorted out - are they 3/8in steel? You need to draw it up in Solidworks (or ACAD or something...) as a single piece then you can have them CNC waterjet-cut out of 3/8in 1018 for $20 a pair...flat parts are easy.
 

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There are three ways to increase braking force:
1. Increase rotor swept area via a larger diameter rotor.
2. Increase piston diameter or number of pistons for more clamping force.
3. Increase brake pad surface area.

[/I]
I've had this discussion a few times on a few different forums.....
#1 and #3 are totally incorrect. (this is a very common misunderstanding)
#2 (clamping force) is the only thing that truly increases braking force
of the three things you mentioned.

Swept area doesn't mean a lot EXCEPT for control of heat - the rotor
is a heat sink in a calorific equation. The more heat you can dissipate,
and the cooler you keep things, the better off you are. And the longer
the rotors and pads last.
Brake surface area is a similar deal. It doesn't effect ultimate braking
force but bigger pads last longer because they handle heat a lot better
than smaller pads. (less ultimate wear and less taper wear due to less
run-up of edge temperature)

Nothing was mentioned about Mu (coefficient of friction).
Friction material is the biggest immediate improvement to a brake system
that significantly effects braking force.

I make no comment about Granada rotors other than they're pretty
small and wouldn't be my choice for any real performance application.

I've been dealing with brake systems my entire career, both sales
and technical aspects.
My resume-
Akebono Brake Corporation
Delco Moraine
Global West GM
 

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I've had this discussion a few times on a few different forums.....
#1 and #3 are totally incorrect. (this is a very common misunderstanding)
#2 (clamping force) is the only thing that truly increases braking force
of the three things you mentioned.

Swept area doesn't mean a lot EXCEPT for control of heat - the rotor
is a heat sink in a calorific equation. The more heat you can dissipate,
and the cooler you keep things, the better off you are. And the longer
the rotors and pads last.
Brake surface area is a similar deal. It doesn't effect ultimate braking
force but bigger pads last longer because they handle heat a lot better
than smaller pads. (less ultimate wear and less taper wear due to less
run-up of edge temperature)

Nothing was mentioned about Mu (coefficient of friction).
Friction material is the biggest immediate improvement to a brake system
that significantly effects braking force.

I make no comment about Granada rotors other than they're pretty
small and wouldn't be my choice for any real performance application.

I've been dealing with brake systems my entire career, both sales
and technical aspects.
My resume-
Akebono Brake Corporation
Delco Moraine
Global West GM
CSRP's SN95 based caliper/rotor/bracket set for Granada spindle uses the dual piston aluminum caliper commonly used on later model Mustang. It uses a single non planer caliper bracket. Key to this discussion is its thicker (1.02") rotor.
 
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