The Kelsey-Hayes disk brake swap is popular and there is lots of information on FABO about this swap, but I decided to make a post to centralize the information. I am NOT an expert, and there may be things in this post that will need to be corrected. I hope that other FABO members correct anything I get wrong and post any additional information that might be helpful for others doing this swap. I just finished doing this swap so everything is fresh in my mind, so that is why Im writing this now. I have benefitted greatly from FABO and writing this post is my way of trying to offer something in return.
Here is what I had before the swap, 9 drums:
There are a couple of different reasons why people may choose the Kelsey Hayes disk brake upgrade. I chose this swap over the 73+ disk brake swap because I wanted to retain my wheels, tires, and rear end. This Kelsey Hayes disk brake swap should work for any A-body with the 5x4 small bolt pattern wheel, EXCEPT those with 13 wheels.
Swapping in the Kelsey Hayes front disk brakes is not complicated. In fact, it is a bolt on replacement that anyone can do without much instruction at all. However, I certainly had several questions, and as I searched this forum and slantsix.org for answers, I could tell others had many of the same questions before me. So I decided to post a how to with as much details about parts as possible, because that is what most of the questions were about.
The donor car in my case was a 1968 Barracuda. I bought the parts here on FABO and spent $435 on upper A arms (which I didnt need), rotors (which I had machined and used), spindles (NEEDED), hubs (NEEDED), calipers (NEEDED, because core charge is $75-100 a piece), lower steering arms (NEEDED), proportioning valve (NEEDED). Here is what I bought:
The first step was to remove my 9 drum brake stuff, spindles, and steering arms. There are three ball joints you will need to dissemble. Choose your method, I opted not to use a pickle fork. I loosen the nut, but leave it on to protect the threads, and then hit the joint hard with a heavy dead blow hammer. I used a jack under the lower control arm to take the tension off the spindle assembly. I reused the boots from my steering arm ball joints, but these are available (around $25 a piece). If you replace your upper ball joints you will need a special ball joint socket to remove the ball joint from the upper control arm, as it is threaded in. The best price I found for this tool is from p-s-t.com at $39 (sku:TOOLBJMOPA;free shipping).
Next, I bolted my lower steering arm and spindle together on my work bench and then bolted it to the control arm and upper A arm. You will want to use the jack to reassemble the spindle to the upper A arm. Then, reconnect the tie-rod end ball joint. Next, I replaced my backing plates, no explanation needed here.
If your installing new rotors you will to need drive out the wheel studs and mate the hub to the new rotors by installing new wheel studs. Be sure to check that the wheel studs are threaded in the direction you want. My parts came off a 68 which would have had left handed threads originally on the driver side, but they had already been swapped out for right handed threaded wheel studs. If your are replacing rotors you will need to decide on a brand to buy. My search revealed that many people complained of the centric rotors (the cheapest) and most people were satisfied with Wagner brand. I actually bought a pair of Wagners so that I have them on hand. I believe drilled and slotted rotors are available at Jegs/Summit.
You probably want/need to replace the inner/outer wheel bearings and oil seal in the hub. If you need directions for this, do a forum search. Basically, I drove them in and out with a punch. I loaded the bearing with disk-break wheel bearing grease (check your grease, some is only for drum bearings). I slide the hub/rotor assembly onto my clean spindle and secured with new spindle nut and cotter pin.
The dust cap is a very tight fit and since mine show through my wheels I wanted to install them without denting them up. I primed and then painted them with chrome color. Another FABO member posted a cool homemade tool for these dust cap installs; cut about a half-inch out of a 2 pvc pipe and then tighten it with a hose clamp. The cap fits inside the pipe and then I hit the pipe to drive in the dust cap. Here is what I used, but a FABO search will also tell you that Dorman part#618-101 fits too.
Next up is installing the new calipers. Before installing you will need to have the supply and cross-over hard lines. My Centric remanufactured calipers from rock auto came with steel cross-over lines but I bought stainless steel cross-over and supply lines from inlinetube. When you are shopping for donor parts, you should be aware that there is a special bracket that connects the rubber brake line to the hard caliper line. Another FABO member (davescuda) has reproduced these for sale (~$35), so if need them you are in luck.
Here is a picture of one of the brackets:
I connected the hard line to the soft line via this bracket before installing the caliper. Installing the caliper would have been a challenge without a friend helping me. It is a heavy devise and threading the mounting bolts from the inside wasnt exactly simple. It was helpful to have someone hold the weight of the caliper as I lines up the bolt hole. After installing the caliper, temporarily install the wheel and make sure your cross-over lines arent hitting the wheel.
Here is a picture of my new and old calipers side by side:
CALIPER TO SPINDLE BOLTS
There are many people who ask about finding the appropriate bolts that hold the calipers to the spindle. I used a grade-8 7/16 20 1.75 bolt from Fastenal, part # below. You can search the forum and learn that some people believe the original bolt is very unique and worth its weight in gold. Consider yourself lucky if you have the original bolts (I think?).
Here is a picture of a stock bolt compared to a modern replacement.
There are many opinions about brake pads for these calipers. Do a search to see what fits your needs. I went with professional grade raybestos. My remanufactured calipers came without the bolts that hold the brake pad clips. These bolts are 1/4"-20 x 3/8 which are pretty short. I ordered 4 from my local Fastenal dealer.
There are also a lot of questions about proportioning valves, search the forums for lots and lots of information. If your car was drum-drum you will have a distribution block that will need to be swapped out for a proportioning block.
The proportioning valve that came with my purchase was date stamped 1975, which would have been for a single piston caliper not the 4-piston caliper. It might not be perfect, but it works for me. I bought a rebuild kit, see below, and used it. Many people opt to use an after market adjustable proportioning valve from Jegs or Summit. I dont doubt that they work better but they also require replacing most/all of your brake lines.
Inlinetube.com sells reproduction Mopar proportioning valves. However, you are also likely to find a used one in the FABO community. Post a wanted add, they are available. The rebuild kit from muslcecarresaerch.com is $15, so consider that when weighing your option of buying a used to rebuild or a new from inlinetube.com, ebay, or jegs/summit.
I forgot to take a picture of my proportioning valve, but it looked just like this.
Here is a diagram of the proportioning valve, from the FSM. The red circle indicates a difference between the weatherhead and kelsey-hayes valve. Musclecarresearch.com will tell you all about it. They have a great thread about an "autopsy" (1970 - 1976 Mopar Combination Valve Autopsy | Muscle Car Research LLC) of one of these proportioning valves and step by step instructions on how to rebuild one with new seals.
And a pic of the distribution block diagram, from the FSM.
I sprayed my distribution block with PB blaster for 7 consecutive days before trying to unscrew my hard lines from the distribution block and master cylinder. This devise is mounted in a challenging place. My torsion bar and exhaust made it a very difficult removal. I didnt even try to loosen the two lines from the master cylinder to the distribution block. I removed the block with those two lines attached, removed them on my work bench and installed them into the proportioning valve on my workbench before installing the proportioning valve. My hard line to my rear brakes stripped even though I was using a line-wrench. Vise-grips to the rescue and I was able to re-use it.
This new disk/drum master cylinder was recommended by several people because the bore diameter of 15/16 made it well suited for my manual brakes. Swapping master cylinders couldnt be easier. Unbolt 4 nuts, remove, replace and tighten 4 nuts (one of mine had a ground wire for my wiper motor).
BLEED AND TEST
Next up, it is time to bleed the brakes, check for leaks, and your done! When your ready for a test drive, replace the wheels and torque them to specs. On my 72 Scamp the manual calls for 55 ft-lbs torque.
PARTS AND COSTS
Here are the parts I sourced, my supplier, and costs (not including shipping). Some of the parts I bought from my local parts store can be purchased cheaper online. My parts store has earned my business and I dont mind paying a little more to support the local economy (I live in rural area).
A great place to find these parts is CLICK HERE - Just search for the part number.
Centric Friction ready calipers (#14163008, 14163007 ) RockAuto -$46, each
Caliper stainless steel cross over and supply hard lines (#SPAB6704, SPAB6707 ) In Line Tube - $40
Raybestos Professional grade pads (PG-D11) local parts store - $35
Raybestos Master cylinder (#MC36406) local part store - $80
Wagner rotors (#BD60257) local parts store - $52, each
Inner wheel bearing set (#BCA-A2) local parts store $9, each
Outer wheel bearing set (#BCA-A6) local parts store $11, each
Oil Seal (National 6840S) - local parts store $15, each
Soft brake lines (raybestos #H66718 ) local parts store $10.00, each
Spindle washer/nut (Dorman HELP#04990 ) local parts store- $6, each
Spindle Dust cap (Dorman #618101 or Dorman HELP#13975) local parts store - $4, each
Proportioning valve rebuild kit musclecarresearch.com - $15
Caliper bolts (Fastenal #18877 ) Fastenal local branch - $4