Disk Swap on an Eaton HO52

[budbeater]

I have not seen any threads on this subject, so since I just finished mine I am going to start one that is worthy of FAQ or sticky. Bear with me because this should take me about a week or so to get right. I have alot of pictures and my upload time sucks!

First: My truck is a 1971 Chevrolet K20. Most of you know that is a longbed 4x4. The rear axle in my truck is the almost indestructible Eaton HO52. The axle shafts are 1 5/8" and very beefy. The problem with the axle lies with the brakes. There were several sizes of drums for this axle and from what I understand multiple sizes were avaliable on the same model year. I had the 12" brakes. The only parts avaliable for the 12" setup is the pads (and perhaps some of the spring hardware.) The cylinders are not avaliable and the drums are not either. Since my passenger wheel cylinder was shot I decided to convert to disks. After looking around at some options I figured for my level of incompetence a pre-built kit would be the best bet.

Several board members recommended the kit from Blackbird Custom Trucks. I found their website and contacted the owner Randy. As most of us know dealing with over-the-phone, catalog, or internet site only businesses can be a royal pain in the butt. This was NOT my experience with Randy and Blackbird Custom Trucks. Even after he had my money Randy would answer my phone calls and patiently walk me through my problems. I don't know if he felt I was a pain in the butt, but he never let me feel like I was bothering or inconveniencing him. Thanks Randy!

Due to time pressures on my end I chose to order a partial kit because I could get the calipers from a local NAPA dealer. THAT WAS A HUGE MISTAKE! Get the whole kit from Blackbird. For some stupid reason the major brake rebuilders are rebuilding the calipers wrong. I believe that they are using a piston that is about 1/8" too long and won't clear the rotor. Absolutely get all the parts from Blackbird. (It was significantly cheaper for me when I finally returned my NAPA calipers and ordered them from Blackbird.) The Kit was ordered on a Tuesday and was at my house on Friday. I live about 800miles from their business site so the shipping was quick I felt.

The whole kit comes with disks, loaded calipers (if you order a kit with E-brake provisions is comes assembled on the caliper), brackets and new hardware where required.

For the project you are going to need:

Tools:
Jack
Jack Stands
Wheel Chocks
Breaker bar (some of this stuff is old and rusty)
Torque wrench
Impact gun (helps, but not critical)
Open/Box Wrenches
Ratchets 3/8" and 1/2" drive
multiple sockets
Shop Press (mine is a 12 ton and worked fine)
Big Screwdriver
Several Flathead Screwdrivers
Big Hammer ( I use both a 2 and 3lb sledge)
Vice Grips (several sizes)
Pliers
Tubing Bender (for new brake lines)
High Speed Cut off tool
Dremel tool
GM brake tool
Spindle Nut wrench

Supplys:

I like to keep my hands clean so I use latex gloves for all the solvent/grease/fluid work
About 6 rolls of shop towels
Grease
Brake fluid
3qts of axle fluid
about 12-20cans of brake cleaner.
RVT Sealant
POR 15 or some other rust treatment paint
200 grit wet/dry sandpaper

Other Parts:

diff gasket
hub bearings
hub/axle seals


Step One: Clean Up your work area. You need clear access around the back wheels,and since you will be pulling the axles you need about 4 feet on each side of the truck.

Step Two: Lets get the truck in the air. Jack that sucker up. Chock the front wheels. Put some great big jackstands solidly under the axle.

Step Three: Lets get the wheels off. Time to break out the impact gun and get the lugs off.

[budbeater]

Step Four: I chose to remove the diff cover so that I could control the exit of axle lube. I didn't want it coming out the ends of the axle housing. You don't have to completely remove the diff cover to drain the diff. Just undo the bottom bolt. I decided to refinish my cover and build a rock ring for it so I took everything off.

[budbeater]

Step Five: Lets take out the axles. There are eight bolts that hold each free float axle in. Remove them and set them aside where you won't lose them. You may have to tap the end of the axle to break it loose. Just a light tap or two should do. Once it is loose carefully pull it straight out so you don't damage the axle seals. Set the axles aside where they won't get dirty. Budget some time to stare at them for awhile because they are really beefy and look indestructable.

[budbeater]

We should now be down to the hub.

[budbeater]

Step Six: Removing the hub.

Here is where we need the spinle nut wrench or socket. It should be the six prong type. The retention pattern is nut, lock washer, nut, washer. You need to take a screwdriver and bend back the tabs on the lock washer so that the spindle wrench can turn the first nut. Take the first nut out then remove the lock washer. The second nut can then be removed followed by the last washer. Go clean these up with either brake cleaner or in your solvent tank and set them aside where they can stay clean.

[budbeater]

Step Six: Removing the Hub (Continued)

The hub should now be free to be removed. Grab it and pull and don't drop it on your toes, it is heavy. Set the hub aside, we will need to strip it down later.

You should now be seeing all the springs, levers, and shoes of a GM drum brake.

[budbeater]

Step Seven: Removing the brakes

We now have to remove the E-brakes, the dust shield for the axle seal, and all the brake junk in order to be able to remove the brake backing plates. You can't get at the end of the e-brake without the rest of the brakes off so dissassembly of the brakes needs to be done first. Remove the 1/2 turn retention screws, the upper springs, the adjuster, and the upper rod and springs.

[budbeater]

Step Seven: Continued

Now everything should be loose enough to get at the E-brake retaining bolt. You might be able to unbolt yours. Mine was rusted enough that I carefully cut it off with a high speed air cutoff tool. Once that is off you will need to pull back the end of the e-brake spring and clamp it with vice grips in order to undo the E-brake cable from the lever. Good luck and wear eye protection.

[budbeater]

By now we should have the brake hardware off (including the shoes, all the springs, levers, etc).

Disconnect the brake line from the brake cylinder. There is no need to remove the cylinder from the backing plate.

The last thing you need to remove to gain access to the bolts that hold on the backing plate is the center dust cover. Small hammers, large screwdrivers, anything that you can use to slowly tap the cover off. It is tight and probably partially rusty so be patient.

Dust cover is indicated by the yellow arrow:

[budbeater]

Step Eight: Removing the backing plate

This step shold be easy. Break out the breaker bar. The four bolts that hold the backing plate are on tight. Loosen them and use the impact wrench to take them all the way off. Take your big hammer and tap the backing plates off. The backing plates can go on the discard, swap meet, or E-bay pile, you won't need them again.

We are now done with dissassembly. You may want to take some time to clean the newly revealed outer axle housing. Maybe some rust preventative paint would be in order. I degreased, sanded and painted the dust covers that we removed at the end of step seven. I used POR-15 to help them last another 35 years.


Step Nine: Installing the New Brackets

Time for new parts. The Kit comes with decent instructions that have about eight pictures. This step threw me at first, but there is really only one way that the caliper brackets can fit on correctly. The open "C" part of the bracket is where the caliper will be mounted. This needs to face the rear of the truck so that the calipers will be mounted behind the axle. The bracket has a thick and thin part. The "C" part is the thin part and the part that mounts on the axle is the thick part. The flat part of the bracket should face the outside of the truck (closest to the wheel). If you put the flat part facing the differential you will not have the correct offset to position the caliper over the rotor.

[budbeater]

Step Ten: Rebuilding the Hub

Part one: Seperating the Hub and Drum

In order to use the hub with the new rotors we have to get the old drum off the hub. You are going to do this by using your shop press. Press out the eight lugs (indicated by green arrows). This will allow the drum and hub to seperate. The hub is indicated by the red circle.

[budbeater]

Step Ten: Rebuild the Hub

Part Two: Choices

Here is where you need to make some choices. You can and should replace your lugs with new lugs. I chose not to because mine looked fine. If yours are rusty or show any signs of over-wear get some new ones.

Bearings: This is a full float axle. The life of the axle will be easier with good bearings. New bearings are avaliable (I got some from NAPA, but I returned them) so it is time to remove and inspect the bearing sets. My bearings looked good since the previous owner had recently replaced the old barrel bearings with newer Timkin style tapered bearings, but I chose to remove them, clean them and repack them. It took some extra time (since I ended up having to cut the old axle seal out), but I am confident that the bearings are now well taken care of.

Clean that hub out. Get out the brake cleaner and solvent tank and get all of the gunk, shavings, and muck out of the hub. Put the bearings back in and tap in a new seal.

[budbeater]

Step Ten: Bebuild the Hub
Part Three: Hub + Rotor

Now that the bearings and seals are taken care of it is time to mate the hub and rotor. Lets go back to the shop press.

Take your Hub and place in the press with the axle seal face up. Set the rotor from the kit on top of the hub and align the lug holes. Drop all the lugs in the holes and push them in finger tight. This will keep things ligned up. Carefully press the lugs in until fully seated. I used some sprayed in white lithium grease to help keep the process bind free. I would recommend working in a crossing pattern much like you would when tightening lugnuts/mounting a wheel. I made sure that all the lugs were fully seated by measuring their exposed length after they seated. No problems appeared.

[budbeater]

Step Eleven: Installing the hub

This should be easy. If you took it off you should be able to put it back on.
Take your newly reassembled hub and rotor and carefully slide it back onto the outer axle.

Find your spindle nuts and washers and install them: Washer, nut, lock washer, nut.

There is most likely a correct torque spec for the spindle nuts. I just did mine the old school mechanic way turn it until is is finger snug, make sure there is not too much end play or bind and then lock it down!

[budbeater]

Step Twelve: Installing the Axles

Retrieve your previously stored axles. Make sure they are still clean. Make sure the gasket surface on the inside of the axle is clean. You could install new steel shim gaskets or clean and reuse the old ones. Carefully slide the axles in and make sure they are seated all the way. Make sure the 8 bolt holts are aligned with the holes in the hub and make sure the axle is centered. Install the 8 bolts and torque them in sequence to 75ft/lbs.

Step Thirteen: Installing the calipers

There are right and left side calipers. The calipers should be installed with the bleeder screws facing up. (Test fit alert: if you are using the calipers with the E-brake provision make sure that the slots/openings in the E-brake lever are wide enough so that the E-brake cable can be slid in. I had to remove mine and widen the slots with a Dremel tool. I don't think this can be done while on the truck so test it first so you only have to put it together once.) Use the supplied silicon lube on the mounting bolts, slide the caliper over the rotor, center it in the mounting bracket, and install the bolts.

[budbeater]

Step Fourteen: Attaching the Hoses, Bending new Brake lines

Coming soon...

[67'ShortMonster]

I did this too my jeep with a h052 in it... I didn't buy a kit though. I used front rotors from a 1993 dodge 1 ton diesel, used studs and attached the rotor to the back side of the hub. Then i used rear brake calipers from a mid 80's cadillac deville, cut some brackets from 3/8" plate. Got the cheapest brake hoses off the shelf that would fit. I think, i was into the whole thing for about $250 Canadian.

[NITRO]

Looks great!! The Rock Guard is off the chart

[drink2mny]

Budbeater, Thank you very much for the compliment given to Blackbird's Custom Trucks. Randy prides himself on trying to help anyone he can.
He truly is a stand up guy that would offer you a shirt off his back.

He would also like to thank you for sending some business his way.

I will be adding and updateing his site with about 5 or more new kits he has developed, as soon as I get back from my deployment.

Thank you again.

[4x4Poet]

Outstanding writeup!

I'd like to see the emergency brake lever slot that needed to be slightly enlarged. What did you do with the two bolt backing plate emergency cable housing bracket? IOW, how do you now keep the housing from moving with the wire rope?

I'd also like to see the brake hose hook ups and hard line reworking with housing bracketry to retain the hard line end since the wheel cyl no longer provides the end anchor.

[AKChevyman]

I am going to mark this thread for later referance.

[Edmond]

Originally Posted by 4x4Poet

Outstanding writeup!

I'd like to see the emergency brake lever slot that needed to be slightly enlarged. What did you do with the two bolt backing plate emergency cable housing bracket? IOW, how do you now keep the housing from moving with the wire rope?

I'd also like to see the brake hose hook ups and hard line reworking with housing bracketry to retain the hard line end since the wheel cyl no longer provides the end anchor.

I would like to know this also.
I have fitted the bracket and cable, but the movement the bracket makes seems so little.

Can you please post some pictures of the bracket and the cable?
That would make it much easier to understand.
Thanks in advance Budbeater.

Cya,
Edmond
Dutch Longhorn

[LostMy65]

Another nice thread lost in time.
Thanks for putting this together with pics.

[freakshow108]

I have done this same conversion but with stock rotors and calipers, and brackets from ruffstuff ind. My only question is what master cylinder, brake booster and prop valve will you be using. Also damn fine thread, this should be helpfull,(understatement), to all who will be going this route!

[72MARIO]

I also got the kit from Blackbirds and randy was great. I had a issue with the stud size and he helped me out. Also the flex lines were missing from the kit and he sent them out the next day no problems.

I am using a 80's vet master cyl and adj porp valve.