A write-up on performing an 8-lug swap on a TTB Dana 44 front axle for Broncos and F-150's

Mar. 01, 2001 By Dustin Siebert

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Here's my write-up on what I did to convert my TTB Dana 44 front axle from 5 lugs to 8 lugs using Chevy parts. At first, I tried going all Ford but after extensive searching and research, there wasn't any way possible I could see to adapt 3/4-1 ton Ford parts to the 1/2 ton TTB axle. After someone mentioned to me on the Ford Truck Enthusiasts Boards how he got his to work using Chevy parts, I decided to look into this in depth. It took me several tries but I finally got it to work.
I'll give you the rundown on what I did but I can't give y'all any specifics on what truck to get parts from. First off- I bought an 10 bolt 3/4 ton axle from an early '70's Chevy K20 4x4 pickup (axle was laying on the ground by itself so don't know exactly what truck).

If you are going to look for one, the main thing to look for is a straight axle 3/4 ton chevy 4x4, not the late '80's with the IFS. I had the yard cut off the knuckles from the axle tubes so I could bring home everything from just the knuckles out along with the axle shafts (didn't need the trashed center section and axle tubes). The biggest thing about this swap is that you have to make sure that the axle you pull your stuff from has the caliper bracket in front of the spindle, not in between the spindle and knuckle.

Items needed for the swap:
spindles
spindle studs
spindle stud nuts and spindle nuts/washer
rotors
wheel bearings
hubs
calipers
caliper backing plates
extended brake lines
outer axle stubs

Chevy 3/4 ton setup with caliper backing plate.

Chevy 3/4 ton setup with the
caliper backing plate in
front of the spindle.

Front view of the Chevy
rotor/hub assembly.

You can see in that picture that the spindle sits between the knuckle and bracket, note the 1/4 inch space between the caliper bracket and knuckle. I started by taking apart all the Chevy stuff I had-

Chevy 3/4 ton setup-
rotor/hub assembly (left),
knuckle and spindle (middle),
caliper backing plate (right)

I then stripped everything off the Bronco knuckles and then proceeded to cut the caliper mounting ears off. I already had both axle beams out of the truck because I was installing a suspension lift at the same time so it was easier for me to do.

Side view of completed cuts and grinding

Side view of my completed
cuts and grinding.

View of the cut caliper
mounting ears.

In those pics, you can see the 3/4 ton chevy spindle that I tried on there to see how it fits. I then knocked out all the Bronco spindle studs by threading on a spare spindle stud nut flush onto each stud then hitting them with a sledge on a block of wood. I then swapped the longer Chevy spindle studs over onto the Bronco knuckle. Here's a pic comparing the stud lengths, Chevy on the left and Bronco on the right-

Chevy studs - left | Bronco studs - right

Chevy spindle studs on the left,
Bronco spindle studs on the right.

You can swap studs with the knuckle still on the axle beams but it is a lot tougher to do. Then I ground a little bit off the face of the knuckle in order to get the caliper bracket to sit squarely onto the knuckle but here's a tip- do NOT put the caliper bracket on this way-

The wrong way to mount the caliper
backing plate. The correct way is
to have the plate mounted clocked
one hole to the left.

I found out the hard way when I was trying to install the calipers and found that it hit that corner of the knuckle. I totally overlooked the knuckle part when I did this originally so I had take everything apart to rotate the caliper bracket one hole over so that the calipers are at the 3 o'clock and 9 o'clock position depending on what side of the truck you're looking at. I also ran into a problem of the Chevy spindle studs being too long and hitting the back of the rotor for some reason. I knocked out all the studs on one side, reinstalled the Bronco studs and found out they were too short.

I then swapped the Bronco studs back to the Chevy studs and cut off 1/16" off all the Chevy studs. Keep in mind, this was with the knuckle still on the beam so I used an impact hammer to get the studs fully seated (had to go in between the gap between the knuckle and axle beams). I had a driveline shop swap the outer Chevy axle stubs onto my Bronco inner axle shafts and replace the u-joints. I slipped the axle shafts in like you normally would with the stock Bronco setup then put the spindles on. I put the caliper brackets on grinding wherever it was needed to get the brackets flush and then threaded the nuts on and tightened everything down. I had to grind the knuckle a little bit so that the caliper itself would clear but nothing major. Calipers bolt on like a normal Chevy truck and the hub locks went on normally too. I bought a set of Ford extended lines and Chevy extended lines because I wasn't sure which would work. I should mention that I got the single piston Chevy calipers (1/2 ton) and it turns out that the Ford extended lines work with the calipers. Here's the completed swap minus the new extended brake lines-

Completed swap minus the
new brake lines.

If any of you attempt this swap, please keep in mind I take no responsibility for any problems that may arise because this is an unusual swap. I should also mention that I did some extensive grinding to the outer surfaces of the caliper brackets and calipers to make my 15" wheels fit and they do fit with very little room to spare-