DISK BRAKE SWAP & MASTER CYLINDERS / BOOSTERS

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I personally believe that a disk brake swap is the most important thing you can do for your car, yourself, and for other peoples lives. If your car cannot stop in an acceptable distance you are a hazard. This was fine in the 1960's where all cars had poor brakes thus if the car in front of you slammed on his brakes to avoid an accident, and you did the same, you both would probably never hit each other as your braking distances were similar and long in distance.
Today, if somebody is driving a modern sports car, or even a 4 wheel disk brake family car like a Nissan Maxima, and they hit their brakes hard you are no doubt going to hit them as a new vehicle braking distances have shortened relative to our old Mopar's drum system. Some people have claimed on web boards that their drum brakes are better than disk systems. They are smoking crack and please ignore this type of insanity. Our A bodies were built 30 years ago and a lot has happened in auto technology since then especially in brakes. The big three and others have invested countless millions of dollars in braking systems over the decades to improve safety and reduce their legal liabilities so learn from them.
Another thing that amazes me are those (NOT ALL) Mopar enthusiasts who swap in 440's, thus adding 150 pounds and a lot of power to their cars, but still want to run their original front drum brakes. I assume they would rather spend the extra money on some go fast part or some chrome goody than an adequate braking system and hide behind those "but it won't be original" statements. Never trade safety for originality unless your car is a trailer queen.

Remember: Its one thing to kill ourselves but another to kill or maim some family out on a Sunday drive since your hot-rodding around and couldn't stop. To date I have known three people who have been killed in auto accidents. My best friends' father killed by a drunk driver on Valentines day leaving behind a wife and six young children. The other two died street racing against their friends in a 68 Mustang during a rain storm in which they learned two valuable lessons: A) Slicks don't have any traction in the rain B) Trees are not soft.
If you don't care about other peoples lives then consider the monetary damages from a resulting lawsuit. If you are found to be somewhat negligent, the lawyers will wipe you out financially to the extent that your next Mopar will be a plastic model toy, and your next set of wheels will be on your trailer home behind the train tracks on the poor side of town.

I don't want to sound like I'm preaching from some high horse but this is an important issue in my opinion. Going 0 - 70 MPH slow isn't going to kill anybody, however going 70 - 0 MPH slow could.

Disk Brake Swaps, The Big Picture:

There are basically three different brake swaps from ridiculously easy to a bit more involved. Costs also run the same way; from cheap to expensive. The first time you pulled your wheels off your car  I'm sure you noticed the smallish front drums on your stock A body. Boy are they tiny and thin, not real safe looking. They don't look like the nice disk setup on my Maxima which has the same vehicle weight. So don't throw money away fixing up yesterdays braking technology, get a disk brake swap going on your ride. Some A - body cars from the 67 - 73 years had 4 piston disk brakes as an option and to swap these over is easy but the parts are rare and hard to come by.

The first version of this swap is to go buy an aftermarket brake kit. While expensive it does save you time tracking down, cleaning, rebuilding and machining parts.
The second version of the disk brake swap involves getting the braking system off a 1973 - 1976 A body and transplanting it on your car.
The third is the Mopar Action big brake swap which came out about twelve years ago and they re-run and update the article every year or so. The big brake swap I will describe as Mopar Action does it and then a second version I and others have done with additional modifications to make it a little bit better. We employ a different hose routing technique and utilize different hoses.

GENERAL THINGS TO KNOW

WHEELS & TIRES

Disk brake swaps require that you change your front rims and tire sizes (except for the 67 - 69 rare factory disk setup) especially if you pursue the big brake option. The original 67 -72 A bodies used a 14" rim in a 4" x 5 pattern while the later 73 - 76 utilized a 14" rim in a 4.5"x 5 pattern. The rims will not SWAP!
Calipers take up more room under the rim than drums. This is not an issue with the small rotor swap but with the big rotor swap. If you decide to go for the big rotor brake swap you will now need to buy 15" rims (15" tires too - another improvement) with the 4.5" pattern as those big rotors and calipers won't fit inside a 14" rim.


REAR END PATTERN

If you pursue the 4.5" disk brake front rotor swap you will unfortunately now have a 4.5" pattern in the front of the car and a 4" pattern on the rear axle, unless you swap the rear end or modify it. However, you can still find 4" mag wheels (but they are rare) out there and run two different bolt pattern wheels on your car. If you go for a big rotor swap you can purchase custom made 15" steel wheels (for the rear) on a 4" pattern from Stockton wheel in California amongst others to match your 15" x 4.5" front wheels.

If this is not acceptable, your options are the following:

1) Swap in a 4.5" pattern rear differential OR
2) Swap your rear end axles.

I will go into rear end axle swapping and axle modifications in detail (i.e. 8 3/4 4.5" axle) in the AXLE subsection but for now a quick review of what we just covered:

A) If you go for the small rotor swap along with a new 8 ¼ or 4.5" pattern modified rear axle you must chuck your 14" 4" wheels but you can keep your tires for a set of new 14" 4.5" rims.
B) If you go for the big rotor swap along with a 4.5" pattern rear end you must chuck it all and buy new 15" 4.5" wheels and tires.
C) If you go for the small rotor swap but no new rear axle you will need new 14" 4.5" pattern front wheels that match your 14" 4" rear pattern wheels. Oh yeah, you will need to also pack two spare tires in your trunk.
D) If you go for the big rotor swap but no new rear axle you must get new 15" 4.5" pattern wheels for the front and custom 15" 4" pattern wheels for the rear and still pack two spare tires.

CORES
Cores are cheaper than you think. Don't bother paying extra money, spend the time pulling, or worry about find the proper calipers or master cylinders at the junk yard. The core charges for master cylinders at Autozone is $5.00 and calipers at Pepboys $10.00 each. Unless you want to use these critical parts as is. NO WAY SHOULD YOU DO THIS!

CALIPER LOCATION
The front disk brake swaps require that the caliper be mounted in the front of the spindle's centerline toward the front of the car, just like the factory, or behind it. If it is in the front it can interfere with aftermarket sway bars but there is a way to get around this if you feel up to doing the additional work.

AFTERMARKET SWAP (and most expensive):
If you have the means to be able to plunk down a $1000.00+ you can buy a front disk brake kit from MP Brakes, Wilwood, Paddock and others. Rumor has it that Baer (www.baer.com) is also developing a kit for the A body. If you buy one of these kits you still have to contend with that rear end pattern problem. A lot of these kits are race only not for year round through the sleet and snow usage. A thousand also bucks buys a lot of beer so what are our cheaper alternatives?

SMALL ROTOR 10.87" SWAP (14" WHEELS):

First thing one needs to do is find a 1973 - 1976 A - body donor car like some nice Dodge Dart and take the following:
Master cylinder (it's different than a drum master cylinder), proportioning valve (different too than a drum setup…What is it? Where is it? Well follow those master cylinder brake tubes down toward the ground to find this metal "block" bolted to the frame - you have now found the proportioning valve. Next unbolt the lower control arm from the lower ball joint attached to the spindle (actually known as a steering knuckle) and unbolt the upper A arm from the frame. The whole assembly that drops in your lap, or in your face if you're under the car, (upper a-arm, spindle, caliper, caliper adapter, hose, rotor) is what you will swap over to your car.

NOTE 1: Some of the older upper A arms (pre 73) may be able to fit the larger 73 - 76 A-arms upper ball joint. But most likely no. You see Mopar increased the diameter of the upper ball joint where it threads into the A -arm and also the size of the "stud" that goes into the top of the disk brake spindle. For some reason there are exceptions to this rule so just to be safe just get those upper a-arms that are coming with the spindles as they are very cheap. You may also want to get the lower control arms, K member, and sway bar to replicate a stock 73 - 76 front sway bar suspension if you don't have a sway bar already or don't like the way the aftermarket versions bolt up. More on that late under "Sway Bars". Approximate cost: $125.00 for everything here at the yards in Texas (Not including K member & sway bar setup).

NOTE 2: Common sense dictates to get rebuilt calipers and master cylinders, resurfaced rotors, new brake pads and bearing seals (check the bearings too!), hoses and associated sealing washers (included with new calipers), and upper / lower control arm bushings/ball joints.
Swap all of this stuff in place of your drum setup and your done. You may want to also check out your old metal brake lines for internal rust while your at it if they are original.
Hey wait… doesn't this mean that my calipers are in front of my spindles? YES it does…however check out the rear hose swap data in the big disk swap. You may be able to use those hoses to work, read on.

THE BIG 11.75" DISK SWAP (15" WHEELS)

Click here for the MA article parts list. I will also list out all of the RAYBESTOS & CARDONE part numbers commonly found at Pep Boys (where I bought my parts from) and exact year / description of the donor car I got my cores from. This will be EASY if you follow my suggestions.
There is a debate between pin type calipers and slider types. The Mopar Action article that this whole swap is based on, and Autocrossers parts list is copied from, use the pin type 70 - 72 B / E body (Charger /Challenger) calipers. I'm sure some slider types would work fine but I don't know what models to use.
In addition you will need to acquire the exact same 1973 - 1976 master cylinder, proportioning valve, spindles (also certain E body spindles work) and upper A arms as the small rotor disk brake swap but you will need nothing else (no rotors, caliper adapters, calipers, hoses).

ARGUEMENTS AGAINST THE BIG ROTOR SWAP
Ok, there are arguements against the big rotor swap that are perfectly valid. First, A bodies are very light cars and probably do not need the stopping power of large rotors as standard late model A body 10.87" rotors are fine for the job. Two, the increased weight of the rotors affects acceleration of the car. I am not going to tell you what path to take but if you want to run a mild street car I would say the stock 73 - 76 system is fine. It is also considerably cheaper without the need to purchase rear proportioning valves to adjust the braking action.

PARTS LIST
You will need to get the following:

Rotors: Big 11.75" 76 - 78 B body or 79 - 81 R body
Caliper Adapters: Take corresponding caliper adapters from above cars.
Calipers: 1970 - 72 B / E body. Examples: 1970 - 72 Charger or Challenger. Just ask the Pep Boy dude for calipers for a 1971 challenger, 383 engine, disk brakes. Raybestos P.N.# RWC 5009 & RWC 5010 or the new brand they carry. Cardone P.N.# A18-4065 & A18-4066
GET DUST SHIELDS off donor car and new foam gaskets for them.
Hoses: Front stock OEM as specified in the MA Article: Raybestos P.N.# BH35017 OR rear mount banjo hoses for Version 2 of the swap: 1979 Dodge diplomat (or 76 - 79 Aspen). Raybestos P.N.# BH36830 & BH36831 OR Bendix P.N.# 77130 & 77131
Master Cylinder: 73 - 76 A body

Rotor
You need real big 11.75" rotors. I got mine off a 1976 Dodge Coronet (B body). I originally thought a 74 B body would have the same rotors but no dice its the small one which makes you wonder if Chrysler got sued for some reason and then put bigger brakes on essentially the same size car.

Caliper Adapter
If you are confused as to what these things are, they are U shaped castings that bolt to the back of the spindle in which the calipers "sits in" and bolts to. You want the caliper adapters that go with your large rotors as their "length" corresponds with the diameter of the rotor so the caliper / pad assembly is properly located on the rotor.

Calipers
Calipers have nothing to do with rotor diameter, the caliper adapter does. However some calipers have larger pistons than others. You want the 1970 - 72 B or E body calipers Raybestos RWC 5009 and RWC 5010. Pep Boys sells these rebuilt by Raybestos for $24.99 + $10.00 core charge each.
NOTE: I bought a pair from Pep Boys and both the right and left calipers were IDENTICAL! THEY SHOULDN'T BE!!!!!! After ordering a second set we realized that somebody over at Raybestos was hitting the crack pipe too hard and accidentally mislabeled the caliper and its box too. Now I'm having a problem with one of the calipers bleeder valves which keeps leaking. Autozone sells a different brand of rebuild (Don't know who) so this may be an alternative to Raybestos which I have mixed feelings on.

The calipers are meant to have a screw in style hose and have a "Y" embossed in the back in which one leg is milled flat and tapped for the hose fitting. The other side isn't. After both calipers are installed in a "frontal" arrangement the tapped holes are on the TOP of the caliper where the hose runs from it under the A arm to the boss welded on the frame which is behind the spindle where the brake line connects. This is just like the 73 - 76 A body OEM hose runs but that uses a different caliper / hose….same concept though.

HOSES
The hoses necessary for the big brake swap depend on the location of your calipers, in front where they interfere with the sway bar or rear where they don't. The famous MA article had them in the front.

FRONT CALIPER INSTALL
1) Crack open a beer.
2) Install your A body upper control arms into car.
3) Install spindles so caliper adapter mounting holes are toward the FRONT of the car.
4) Bolt on caliper adapters.
5) Bolt on dust shields (new foam gaskets too) and install rotor.
6) Install brake pads and caliper so hose fitting hole is on the TOP of the "Y" and pointing toward the REAR of the car.
7) Run straight hose P.N.# BH35017 from that "Y" (remember sealing washer) under the A arm to the hose frame mount, insert retaining clip.
8) Hook up brake line, bleed brakes.
9) Your Done…. Miller time.

REAR CALIPER INSTALL
This is a little more involved, there are two versions of this install however they are identical up to the hose routing:

1) Crack open a beer.
2) Install your A body upper control arms into car.
3) Install spindles so caliper adapter mounting holes are toward the REAR of the car.
4) Bolt on caliper adapters.
5) Bolt on dust shields (new foam gaskets too) and install rotor
6) Install brake pads and caliper so hose fitting hole is on the TOP of the "Y" and pointing toward the FRONT of the car.

HOSE ROUTING VERSION 1 (MOPAR ACTION)

7) This JPEG stolen from my friend over at Thunderstruck as a picture tells a thousand words. Cut a brake hose mounting flange off a donor car and weld it in front of the caliper on the frame (or cut yours off and relocate it if you plan to run custom brake lines).

8 ) Run a short brake line with a coupler from the original OEM brake hose mounting location forward to your new one.
9) Run the same brake hose P.N.# BH35017 from the caliper (remember sealing washer) under the A arm to the new location you have created, install retaining clip.
10) Hook up brake hose to new extension you have installed and bleed brakes.
11) Your done….Miller time again.

HOSE ROUTING VERSION 2 (NOT MOPAR ACTION)

You will need a "banjo" or "loop" type hose to pull this one off approximately 16" or longer. These can be bought, OEM style from your local parts place, from Mopar Performance for a stiff fee, or can be purchased from "RUSSELL" brake products. Russell makes all of those pretty brake hoses and oil/coolant/etc. fittings… sort of like Earls.

The magic OEM hose is the Raybestos P.N.# 36830 and 36831 (or Bendix P.N.# 77130 & 77131). Fits 1979 dodge diplomats and
76 - 79 Aspens. You will also need to order two caliper bolts for both sides of the vehicle (the bolt is hollow so brake fluid travels through it) for this application, I don't have the part number but just ask for the ones for the hoses NOT the calipers which didn't require them. The hose sealing washers on the rebuilt calipers will work with this hose/bolt setup. You will also have to remove some goofy attaching bracket clipped on the hose. Don't damage the hose doing it…I used two vice grips and a screwdriver to get it off.

Installation:

7) See GIF for explanation. You need to use the proper hose for each side. This hose is supposed to be offset toward the inside so its close to the spindle for turning clearance.
8) Put brass sealing washer on bolt, pass through loop end, put brass washer on the other side…like a sealing sandwich.
9) Screw caliper bolt into caliper fitting with the hose in a downward sort of "hugging" the spindle close as possible with out hitting it.
10) Take other side of hose and loop it up to the factory mounting boss.
11) Install retaining clip and attach brake line and bleed system.
12) Your done.

UNFORESEEN PROBLEMS

BLEEDER SCREW & HOSE LEAKAGE
Well I currently have a few problems I have run into with the diplomat banjo hose but not because of the design. Most sites will say "hey it bolted right in" but lets be honest it never goes as easy as that.

The first problem is after I pumped the brakes up the caliper moved inward to the car thus my snug to the spindle hose routing became 3/8 too much so I had to loosen the hoses, move them back in, and tighten it back up again.
The second problem was leakage between the caliper body and the sealing washer in the hose loop end. The banjo/loop hose is designed for a caliper that has a smooth machined boss to be tightened against. The 70 - 72 caliper was designed for a screw in hose not something that was supposed to seal against it. Supposedly the flat boss on the caliper (from what I've heard) is smooth enough for the sealing washer to work - NOT MINE. My wonderful Raybestos rebuilds were pitted all around the circumference of the tapped caliper hole so much that the brass washer couldn't compress enough to fill all the irregularities in - I guess acceptable for a 26 year old core. I also did what every car guy does…just make it tighter. That didn't work and I was afraid to break off the bolt - it was that tight. I had to resort to removing the calipers, sticking a little piece of paper towel into the caliper hole to seal it up and hand filing the boss until smooth.
Once I reinstalled them one still leaked….arrrghh! So I had to go buy new sealing washers since mine were all crushed out and distorted from the pitted caliper face (as I installed and reinstalled them 4 times) and wouldn't hold a seal. With new copper sealing washers they worked great. Now I just have that pesky caliper bleeder screw to contend with. I'll replace the bleeder screw next and if it still leaks I'm returning the caliper.
In retrospect, I was looking through the Russell performance catalog at brake hoses and fittings. They seem to have a nice set of 90 degree screw in caliper hose fittings and universal hoses too. This can be an option for you to consider.

BRAKE PAD PROBLEMS
I was running the semi-metallic Raybestos pads and was having problems stopping the car until the brakes were hot which was never. I had the same exact problem with my old BMW 325I that wouldn't stop at all when the brakes were cold. Well, I have learned that this problem is with semi-metallic pads used on large rotors. Since the big disk swap rotors are so large they don't heat up enough, especially with the light A bodies, thus the semi-metallics do a lousy job slowing the car down. The solution is to run organic pads and this has solved a lot of my problems.

UPDATE 1/4/99
The caliper was defective. I went back to Pep Boys and returned it. As of 12/31/98 Pep boys was no longer carrying these particular Raybestos calipers I had suggested. However, the brand that they are carrying is Cardone. These calipers are great. The hose boss on them is actually machined flat with circular grooves for a better washer seal. The Raybestos had none of this extra work just a pitted boss and the resulting leaks. I am very impressed with the Cardone rebuilds. Cardone part numbers needed for the swap are P.N.# A18-4065 & A18-4066

BRAKING IMBALANCE
Having fat front rotors is a treat. I can now almost out brake most cars on the road. However there is a common problem with this setup that is easily remedied. The back brakes tend to lock up before the front brakes which is not good (fishtail in the rain). Solutions below:

1) My 8 3/4 from a Fury cop car with 11" drums uses a 15/16" rear wheel brake cylinder. Look closely at your rear end as you may have the same size, if you are unsure change it anyway as cylinders are $9.00 or so and why not put new ones in your car. If you swap out to a 7/8" or 13/16" version (old mopar P.N.# 2530136) the rear brake action will be lessened. These wheel cylinders were supposedly used on vans and trucks in the 80's. If anybody has the proper year and make of van, or current part number, I'd appreciate it as my old Mopar part number is no good and I can't cross reference it.
NOTE: Running large rear drums is a total waste of time as they contribute 30% or less to the braking of the car, are too heavy, and overkill in a lightweight A body. Unfortunately they tend to come on 8 3/4 4.5" pattern rear differentials that are found in the larger donor cars that we shorten up and we swap into our A bodies. I don't know of an 8 3/4 4.5" brake setup in the 9" or 10" range. If anyone knows please tell me.

2) You SHOULD buy a brake proportioning valve from Summit, Jegs, etc. and install it in the rear brake line AFTER the factory proportioning valve. Especially if you are running ridiculously huge rear drums like I am. I have done this with a nice unit from Wilwood. This way you can find a snowy day with a friend and dial in that rear brake action by slamming on your brakes and adjusting them in order for your fronts to lock up a little before the rears. At the factory these valves were one size fits all and not adjustable. If you decide to experiment with different size rear tires and rims, hence different rotational masses, you must buy a valve and fine tune your combo. Smaller wheel cylinders do help get the rear braking action in the ballpark but the valve brings you to home plate.

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