1979 Ford F-150 - Project Two-By Four, Part 1

This is how our front suspension...        read full caption This is how our front suspension started. We didn’t reuse any of the two-wheel-drive components so the installation would be the same if the truck is stock or lifted. The steering linkage and box is behind the I-beams on two-wheel-drive ’66-’79 Ford F-100s, F-150s, and F-250s. The suspensions are almost identical on these trucks as well.

Our Dana 44 came rebuilt from...        read full caption Our Dana 44 came rebuilt from Boyce Equipment. New calipers, locking hubs, freshly turned rotors, and a new tie rod and ends were only some of the features. It also came in a fresh gloss-black skin.

We swung the 44 under the...        read full caption We swung the 44 under the frame after removing all of the two-wheel-drive components and marked where the crossmember needed to be notched. The crossmember could be removed and replaced with a smaller unit, but the motor mounts are attached to it so we decided that notching it was the best solution for clearance.

This is how we notched the...        read full caption This is how we notched the front portion of the crossmember. The differential now has room to fit up inside the channeled factory crossmember. The backside is also clearanced for the pinion and one of the links.

The lower-link brackets are...        read full caption The lower-link brackets are made from 3/16-inch mild steel, 1 1/2-inch 0.120 wall tubing, and heavy-wall 5/8-inch inside diameter DOM tubing. They are located on the frame using holes that had been stamped into the frame at the factory. This ensures that the brackets are mounted in the correct positions.

We built our own threaded...        read full caption We built our own threaded tubing adapters, but they can be purchased from circle track and drag race suppliers. We used a 3/4-inch tap to thread short sections of heavy-wall DOM tubing for our adapters.

All three links are cut to...        read full caption All three links are cut to the same length and the mounts are tack-welded to the axle. The links are mounted parallel so there is no caster change during suspension cycling.

The factory Ford two-wheel-drive...        read full caption The factory Ford two-wheel-drive steering box (right) has a grotesquely long sector shaft that can snap if abused. We moved the steering-box mount to a position in front of the axle and used a common GM car box (left).

With everything tack-welded...        read full caption With everything tack-welded and mocked up, we then cycled the suspension to see what would hit where. The bumpstop positions are located with this information.

We boxed the driver side front...        read full caption We boxed the driver side front framerail and built a steering box mount by piercing 1 1/8-inch heavy-wall DOM tubing through both sides of the frame. This is the strongest way to mount a steering box. Everything is tack-welded and checked before the final welds are burned in.

Flaming River supplied a collapsible...        read full caption Flaming River supplied a collapsible double-D shaft with U-jointed ends that fit our GM steering box. The Ford column was cut and ground to match the double-D joint.

Once all of the mounts were...        read full caption Once all of the mounts were positioned where we wanted them we removed the axle for finish welding. It’s best to weld small sections at a time to keep the housing from distorting.

The threaded ends are welded...        read full caption The threaded ends are welded to the ends of the links, and they have two rosette or plug welds for additional strength. We removed the Aurora rod ends before welding to keep them from being damaged during the welding process.

We built our crossmember using...        read full caption We built our crossmember using 1 1/2-inch 0.120 wall tubing. The upper link is bolted to this component. The transfer case shifters and the transmission will also be mounted to this structure.

The Autofab 4 1/2-inch urethane...        read full caption The Autofab 4 1/2-inch urethane bumpstops should only be compressed to about half their height. Building the bumpstop mounts so that metal contacts metal at full bump eliminates the possibility of over-compressing and damaging the urethane. A loud clank can be heard when we get too crazy, which lets us know we need to slow down.

To convert our Chevy axle...        read full caption To convert our Chevy axle to a five-lugger we called 4 Wheel Parts Wholesalers and ordered new hubs and rotors for a ’73-’79 F-150. The Chevy wheel bearings and calipers fit the Ford components. We added Warn locking hubs and Skyjacker vinyl-coated stainless steel brake lines.

This is the almost complete...        read full caption This is the almost complete steering and suspension. The tie rod is made from 1 1/2-inch 0.120 wall tubing. Aurora rod ends cinched with Grade 8 hardware allow movement at all pivot points. The drag link and Panhard rod are almost parallel—and they’re the same length—so bumpsteer was minimal when we cycled the suspension.

If you have a two-wheel drive and you’re fed up with getting stuck, or your buddies with four-bys just plain leave you in the dust, then it’s probably time to sell the pegleg, step up to the plate, and buy a 4x4. Or is it?

Two-bys can be lots of fun for high-speed use, and our ’79 Ford F-150 was no exception. It certainly wasn’t a slouch with 35-inch tires and 17 inches of travel in the front, accompanied by 14 inches in the rear. Jumps from 5 feet were no problem, and dips and bumps were easily absorbed. However, dune and mud runs had left us stranded and wanting a 4x4. In some situations low range would have been nice too. We have a lot of time and money wrapped up in our truck, including a new engine, tranny, and rearend. It didn’t make much sense to sell it and start over, so we decided to convert it to a 4x4. It is possible to buy a 4x4 of the same make and bolt on all of the good parts and sell the leftover truck, but we just couldn’t part with our ’79.

Planning

Now that we decided to keep the truck, we needed to decide how to go about the conversion. Bolting on factory ’73-’79 Ford 4x4 components (tranny, transfer case, axle, and suspension) might seem like the easiest method, and it is for many models. It turns out that the ’66-’79 Ford two-wheel-drive frames are different from the four-wheel-drive frames. The main difference is the engine crossmember. The 4x4 crossmember is made from square tube and is positioned in front of the engine, away from the axle assembly. The two-wheel-drive piece provides a mounting location for the I-beams and hangs below the engine. It needs to be removed or modified unless a huge lift is planned. We were lifting our truck 6-7 inches over stock.

Another complication is that the transmission in your two-wheel drive is probably fine. This was the case for our truck, so it seemed wasteful to swap it out for a 4x4 trans mated to a transfer case. A divorce-mounted transfer case was the perfect solution. Divorced Dana 24s and NP205s are somewhat common in wrecking yards and can be found relatively cheap since they hardly ever break. A divorce mounted ’case would also help with weight distribution by moving a good portion of bulk to the rear of the vehicle. The third advantage that came to mind was that we could clock the transfer case for more ground clearance. We didn’t need an expensive adapter, just a third driveshaft. We decided on a divorced Dodge NP205 to provide splitting duties.

The Dodge transfer case has the front output on the passenger side. This offers us plenty of options for a front axle but we have our limitations too. Custom units were too expensive and we wanted to be able to buy spare parts from wrecking yards if need be. Ford axles have the differentials on the wrong side, and the high-pinion design would have caused major clearance problems with the factory two-wheel-drive crossmember. Chevy axles have the diff on the same side as the Dodge transfer case and are more common than Dodge axles with 5-on-5 ½ lug patterns. So Chevy it was.

We thought that a bombproof Dana 60 would be nice, but we doubted that its size and weight were really needed. In fact, it was too heavy and probably way overkill for our high-speed, nimble truck with 35-inch tires. It was also an expensive option that would need to be converted to a five-lug or we would have to swap out the rear axle to match the eight-lug front. A Dana 44 from a ’73-’76 Chevy was deemed to be the best option. It has ½-inch-thick, 2 ¾-inch-diameter axletubes, the diff is on the correct side, lots of them exist in wrecking yards, and the six-lug pattern could be easily changed to 5-on-5 ½. It turned out that the width was only slightly wider than the factory Ford 9-inch in the back of our truck. A call to Boyce Equipment netted us a rebuilt Dana 44 with 4.10 gears to match the back. If your project or budget calls for a 10-bolt, a Dana 60, or even a 2 ½- or a 5-ton axle, Boyce has them all.

Suspension

The truck was originally built as a high-speed desert runner, and we didn’t want to lose that capability with the integration of four-wheel drive. Leaf springs would have been simple to install since the perches on our axle were about the same width as our framerails. Coils could have been mounted in the original (aftermarket in our case) coil buckets, but installing Ford radius arms on our Chevy axle posed its own set of problems. Neither of these designs would look or perform any different than a normal straight-axle Ford 4x4. Also, if long travel is built into the factory radius arm suspension there will be significant caster change throughout the travel. Articulation would also be limited by the presence of the C-bushings. We knew it would be difficult to keep the 17 inches of suspension we originally had and still maintain safe steering linkages, but we were willing to settle for a little less travel in exchange for four-wheel drive.

We chose to build a three-link suspension with a Panhard rod. Coilover shocks will compactly and economically perform damping and rebound chores. The links are attached to the axle and frame with Aurora rod ends on 1 ½-inch DOM tubing. The tubing has a wall thickness of almost 3/8 inch so it can handle rocks and just about anything we hit it with. All three arms are the same length, and the upper and lower arms are parallel to each other. This ensures that there is no caster change throughout the travel and we only need to carry one spare arm. The axle is kept inline by a 11/8-inch-diameter, heavy wall DOM Panhard rod with Aurora rod ends. The drag link is made of the same material. Both components use the same rod ends and both are the same length, so again, only one spare is needed.

Staying true to the find-it- anywhere motif, we ditched the behind-the-engine steering and chose a ’70-’78 Camaro Saginaw power steering box that has 2 ½ turns lock-to-lock. The box is a 76 GM 800 unit with the larger bearings and stronger casting. This box has the same bolt pattern as many American cars, so a field replacement should be a snap if it should ever fail. The box is connected to our factory column with a Flaming River collapsible steering shaft. We built our own steering-box mount using DOM tubing that pierces the freshly reinforced framerail. This month we’ll cover the axle installation, steering, and the three-link suspension design. Next month we’ll cover the transfer case, driveshafts, the shocks, how to build the shock hoops, and any leftover details.

Necessary Tools

•Common hand tools

•Angle finder

•Assorted files

•½-inch drill

•Assorted drill bits and hole saws

•Grinder

•Welder (preferably MIG or TIG) with at least ¼-inch single-pass capability

•Sawzall, torch, or plasma cutter

•Chop saw

•Extra-tall jackstands

•Ratchet straps

Optional Tools

•Tube bender: can be used to make cool shock hoops and brackets

•Tubing notcher: copes tubing for easy fit-up and welding

•¾-inch fine thread tap

Materials

•3/16-inch mild plate steel: size and amount will depend on bracket design

•1 ½-inch 0.120 wall mild steel tubing: 15-30 feet

•1 1/8-inch DOM tubing with 5/8-inch inside diameter: 4 feet

•1 ½-inch heavy-wall DOM or chrome moly tubing: amount depends on the length of the links

•11/8-inch heavy-wall DOM with 11/16-inch inside diameter: length will depend on drag link and Panhard rod design

Parts

•Wrangler shackle bushings (two pair)

•PFTE- (Teflon) lined Aurora rod ends (size and type will depend on use)

•King Prerunner coilover and standard shocks and hardware

•Eibach coils

•Divorced Dodge NP205

•’72-’76 ½-ton GM Dana 44 front axle

•’73-’79 F-150 hubs and rotors

•Skyjacker stainless braided lines

•Warn locking hubs

•Miscellaneous Grade 8 hardware

•Autofab 4 ½-inch bumpstops

•Flaming River steering shaft

•GM 800 steering box with Camaro pitman arm

•Driveshafts

•Transfer case shift linkage

•Wheels and tires

•Lift for rear

To read "Project Two-By Four, Part 2: Shocks and Hoops," click here

. For Project Two-By Four, Part 3: Driveline and Airtime, click here .