The Kelsey-Hayes Disk Brake Swap Thread

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57dodged100

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The Kelsey-Hayes Disk Brake Swap Thread

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 I’m 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:
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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.

DONOR PARTS:
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 didn’t 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:
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DISASSEMBLY
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).

REASSEMBLY

SPINDLE/CONTROL ARM
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.

ROTORS
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.
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WHEEL BEARINGS
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.

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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.
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CALIPERS
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:
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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 wasn’t 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 aren’t hitting the wheel.

Here is a picture of my new and old calipers side by side:
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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 it’s 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.
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BRAKE PADS
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.
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BRAKE HOSES
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PROPORTIONING VALVE
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 don’t 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.
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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.
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And a pic of the distribution block diagram, from the FSM.

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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 didn’t 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.

MASTER CYLINDER
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 couldn’t be easier. Unbolt 4 nuts, remove, replace and tighten 4 nuts (one of mine had a ground wire for my wiper motor).

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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 don’t 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 #618–101 or Dorman HELP#13975) – local parts store - $4, each
Proportioning valve rebuild kit – musclecarresearch.com - $15
Caliper bolts – (Fastenal #18877 ) – Fastenal local branch - $4

Read more about this article here...
 
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Informative post, thank you. Do you know if the KH brakes have about the same clearance as 10 inch drums? Wanted to know if my 14 inch sbp Mag wheels would fit ok.
 
Great post with good info and I appreciate the part numbers and cost being included.
 
Informative post, thank you. Do you know if the KH brakes have about the same clearance as 10 inch drums? Wanted to know if my 14 inch sbp Mag wheels would fit ok.

I don't know for sure. I'm running 14" stock poverty rims and there are no problems.
 
I looked up MC part number and it was for power brakes, does it matter if it goes on manual set up?
 
I looked up MC part number and it was for power brakes, does it matter if it goes on manual set up?

This master cylinder part number is a popular one for this application, see these links, as examples. Do a FABO search for MC36406 and even more threads will come up….

http://www.forabodiesonly.com/mopar/showthread.php?t=265382&highlight=Mc36406

http://www.forabodiesonly.com/mopar/showthread.php?t=254668&highlight=Mc36406

http://www.forabodiesonly.com/mopar/showthread.php?t=248587&highlight=Mc36406
 
Those factory shouldered bolts that hold the caliper to the spindle have a shoulder for a reason. Those replacement bolts probably don't fit very snug in the caliper and may loosen up over time. Could be dangerous.
 
Those factory shouldered bolts that hold the caliper to the spindle have a shoulder for a reason. Those replacement bolts probably don't fit very snug in the caliper and may loosen up over time. Could be dangerous.

You might be correct. As they say, time will tell.

But I doubt it will be a problem. The caliper is very snug. If the two bolts are torqued to the same pressure, I'm not sure why the shoulder of the factory bolt would provide any additional fastening strength. I'm pretty obsessive when it comes to maintenance. I plan on putting a wrench on those bolts every time I do an oil change, maybe more frequently early on, just to be on the safe side.

I know this doesn't really matter, but I do know other people who have run replacement bolts for many years and not run into any problems.

As I mentioned in my original post, I'm aware that some people believe the original bolts are special and superior to modern replacements. They are obviously unique. There was a FABO member that indicated he was going to have these bolts remanufactured, but I think the cost was prohibitive.

I think most people are going to use the original bolt if they have access to it. However, if you have all the other parts but are missing these bolts, then I think using grade 8 bolts (and checking them regularly) is a reasonable alternative.

If someone has had experience with replacement bolts failing or causing safety problems, please post that information.

If someone has had positive experience with replacement bolts and have used them for a period of years, please post that information.
 
Going from the 10's to a disk, the LBJ mounting holes just went from 1/2 to 9/16. I drilled my drum ones out and they worked perfectly. I had just bought them but they are probably the same price as the disk LBJ's. The later 5 on 4.5 stuff had the larger upper ball joint. Good point on the stock combo valve. I used one too after I couldnt find my Summit adustable. Made plumbing that much easier, just had to bend a few tubes to make it work and I think I needed 2 adapters.
 
Those factory shouldered bolts that hold the caliper to the spindle have a shoulder for a reason. Those replacement bolts probably don't fit very snug in the caliper and may loosen up over time. Could be dangerous.


Hmm,I doubt it. Clamping force comes from the threads. If it's a real worry,could always sleeve the bolt for a snug fit.

I tend to worry more about the wear areas on the calipers,where the brake shoes slide. Those,if grooved can cause brakes to stick. Not a good thing.
 
How much are the rotors? I hear they can be expensive.
 
All the part number and prices are in original post. I paid $52 for rotors, they can be had for $45 on ebay.
 
Thanks! I can't tell you how much this will help when I switch mine over this year. Thanks again.
 
I looked up MC part number and it was for power brakes, does it matter if it goes on manual set up?

The 15/16 MC gives slightly less pedal effort. The original manual disc MC had a 1-1/32 bore, and made for a very stiff pedal. People who are used to power brakes tend to think it's broken...

Great thread, BTW.

I recommend the Summit slotted cross-drilled slotted rotors for pretty much the same money (I think they were $80/pair), made in USA. I am also using Summit's ceramic brake pads, and they survived the Willow Springs road course test -- they really bite, and do not fade.

The K-H brake setup is a solid design (4 piston fixed caliper with vented disc -- that spec sounds more like a Porsche than a Plymouth), and now that parts are getting more available, I don't see any downside. People used to complain the pistons would freeze up, but those were 30 year old seals. If you use them regularly, I don't see a lot of problems.
 
Do you have to change out the master cylinder push rod going from a drum to disk master cylinder?
 
I recommend the Summit slotted cross-drilled slotted rotors for pretty much the same money (I think they were $80/pair), made in USA.

I don't think Summit carries them anymore. :(
 
Bookmarked...I have a set of these in boxes when I get back to my project in about 3 1/2 years-thanks man!
 
Also if needed. Get these Brackets from davescuda or Jim's 70 Dart
35.00 pr shipped

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Very useful post. Thanks for taking the time. I don't see a concern with using the grade 8 bolts instead of special "shoulder bolts" for 3 reasons:

1) I just replaced front pads on my 84 M-B 300D, which has a similar design - fixed caliper and rotor that bolts to inside of hub. Actually, a lesser design since 2 pistons (not 4) and solid rotor (not vented). Anyway, the 2 bolts that attach the caliper look like the ones you used. I didn't notice any special shoulder or tight fit in the caliper holes. Don't 73+ A-bodies have a caliper bracket that bolts to the spindle? Does it use special bolts? I recall my 2002 T&C is like that and has regular bolts.

2) Unless the factory bolt was a very tight fit, more like a tapered ball joint stud, I don't see how it would prevent radial play. They would still rely on the clamping tension providing interface friction.

3) The forces on a brake caliper are among the most predictable of any in a car. There are two limiters - when the pads slide on the rotor and when the tires slide on the road. A rough calculation gives <1000 lbf when the tires skid. That is trivial in the world of 7/16" bolts.
 
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