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Rear Disc Brake Conversion

July 11th, 2009 Posted in Brakes, Rear Axle, Tech

The Dana 60 rear axle we’re building came from a ’92 Ford E-350. In ’96, E-350s started getting a rear disc brake option. We were really hoping to pick up a brake setup from one of those because it includes a mechanical parking brake in the “hat” of the rotor. We didn’t have any luck finding one at our local junkyards, so we came up with a bolt-on do-it-yourself setup (no parking brake for now) and we’ll keep our eye out for a newer E-350 setup.

Dana 60 rear disc conversions are usually pretty straight forward – just pickup some cheap 3/4 ton Chevy calipers and rotors and a pair of standard caliper brackets and you’re good to go. The rotors are held to the back of your hubs with the lug studs (which press into the hubs) and the caliper brackets are welded on at the correct height.

Unfortunately, this was not going to work for us because of the massive hubs this axle came with. The lug stud holes were far too big for the typical stud used in this conversion and there is no suitable stud made (in a 9/16-18 thread to match the front) that would press into our hubs and still leave room for the rotor on the back side.

This is the stud meant for our application… for a rotor to be held on to the back of the hub, we would need a similar stud with about half an inch in between the knurl and the head.

We didn’t want to swap out the hubs (since then our D70 shafts probably would not fit) and we didn’t want to try to redrill the hubs, so we started looking for rotors that would work on the outside of hubs. What better place to start than the ’96+ E-350 rear rotors?

The overall diameter of the E-350 rotor is 5/16″ bigger than that of the ’80 Chevy K20 rotor that is most often used in this conversion. The face of the rotor (braking surface) is 3/16″ shorter and the width of the disc (the part of the rotor between the brake pads) is about 1/8″ thinner. So, the E-350 rotors seem to be close enough to use with the K20 calipers if we can find/make a bracket with the correct offset and height.

We had a pair of Ruff Stuff Specialties’ Dana 70 caliper brackets laying around, so we gave them gave them a shot. Much to our surprise, they bolted right up to the stock flanges on our Dana 60…

and the offset was a perfect match for our E-350 rotors!

There was just one catch… the brackets were about 1/4″ too short!

We could have just raised them 1/4″ and welded them to the flanges, but we really wanted to be able to easily swap in the E-350 factory brake setup in the future, so we picked up a second pair of brackets from Ruff Stuff to cut up and extend ours. We did consider welding up the hole, drilling a new hole and then tapping it, but decided that the weld would be too difficult to tap.

So, we cut the end both brackets…

and chamferred the edges so that when we ground the surface down smooth, we wouldn’t be grinding away all of the weld.

Then welded them back together so that they are a little taller than before.

We used one of the the uncut brackets as a jig so that we knew our caliper would still bolt up to the modified bracket.

Then we ground the bracket down smooth and gave it a coat of paint.

The’s plenty of room under the 16″ wheels.

For simplicity, we ran all stainless steel braided lines for the rear. We got all the lines and fittings from Speedway Motors and it didn’t cost any more than if there was a hard line in the middle.

  1. 4 Responses to “Rear Disc Brake Conversion”

  2. By Brock Lenson on May 1, 2011

    Hi, what size are the rotors you used? I am trying to convert a 1968 ford dana 60 with semi floating 5×5.5 axles the rotors I want to use are 11.75 dia.
    thank’s Brock

  3. By JeepFreak21 on Jul 4, 2011

    Sorry I didn’t see your question earlier Brock. I believe they’re 12.5″ rotors. Try searching RockAuto.com for the rotors you need. They’ve got measurements on most of their parts.
    HTH,
    Billy

  4. By skip hire Watford on Dec 16, 2013

    Hey there just wanted to give you a quick heads up. The words in yojr post seem tto be running off the
    screen in Safari. I’m not sure if this is a format issue or something to
    do with internet browser compatibility but I figured
    I’d post to let you know. Thhe design look great though!

    Hope you get the problem resolved soon. Many thanks

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