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.

[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.

[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

[AKChevyman]

I am going to mark this thread for later referance.

[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.

[riceranch]

Thank you so much for posting this, I'm in the midst of sorting out the rear brakes on my newly acquired K20 3/4 ton suburban and am coming to the conclusion that I'll be doing this prior to finding a decent set of rear drums for the HO52 that's in the rear.

[whitedog76]

A rotor from a 2003 and newer van/2000 and newer truck will slide over the hub of early HO52s with the front mount drums. Not for sure on the rear mount drum hubs.

I've been working on a disc kit with components from an 03 van. The only real obstacle I've encountered is finding a machine shop that will cut some flanges for me. I'm almost to the point of buying some plate steel and a bunch of hole saws and doing it myself.

All the components are also availible from GM and are priced reasonably. BTW-the truck brakes are priced better than the van.

Here's what it looks like.

http://s1074.photobucket.com/user/wh...tml?sort=6&o=1

[ChrisWhewell]

Awesome, so GM has a retrofit kit ? I'd like to know more. My 67 k20 needs rear brakes. I notice Eckler's sells drums and all the other stuff, but is it better maybe to go with a GM kit and switch over to discs on the rear ? Or should I just keep them drums on the rear ? I do use the truck to tow if that matters

[Tdrcreyn4]

Great post!! Thanks!!