Designing a new front suspension.
In the last installment, we left you with an overview of how we plan to convert an '04 F-150 FX4 into 4-Wheel and Off-Road's new desert runner. This month the truck is in the hands of Jesse Nelson and Dave Dinsmore at JD Fabrication in San Marcos, California, to begin the new long-travel suspension and drivetrain modifications.
JD Fabrication started by focusing its attention on the all-new Ford IFS and has developed a plan to build a custom front suspension that is stronger and much more bump-friendly. The stronger part is no problem for Nelson and Dinsmore. Everything these guys build leans toward overkill. So naturally their material of choice for our Ford's new suspension is nothing less than 4130 chromoly steel. Building suspensions that handle bumps is no problem for these guys either--they eat, breathe, and sleep the stuff.
They knew the front would keep an A-arm design, but they planned to lengthen the arms for increased suspension travel without binding the CV-shafts. They also have plans to upgrade the shocks with Bilstein 9100-series coilovers and hydraulic bumpstops. Are you drooling yet? Well, if all this doesn't excite you, what if we told you that JD Fabrication also plans to offer our trick new suspension as a kit for your new F-150? Yeah, we thought you'd like hearing that.
So this month we'll walk you through the front suspension design and pick up next month with the upper A-arms and rear suspension. At this point we've got a lot of seat time in stock '04 F-150s, and love the way they perform in the high-speed rough stuff. We can't wait to see what these trucks are capable of after JD Fabrication gets done with ours.
The new lower A-arms started life as a half-dozen cardboard templates that were transferred to 1/8-inch-thick 4130 chromoly sheet on JD Fabrication's trace cutter. The trace cutter works by automatically "tracing" the edge of any white cardboard template (on the right) to move a plasma torch connected by an arm (on the left) in the exact same shape. | 
After they're cut out, the chromoly pieces are assembled in this jig so that they can be TIG-welded together without distortion. The new-boxed arm is longer than stock, but maintains the original mounting point and ball-joint angle. | 
The new JD Fabrication arms are significantly stronger (and heavier!) than the cast-aluminum Ford pieces they replace. The lower shock mount still has to be added to the arm along with a reinforced striker pad for the Bilstein hydraulic bumpstop, but you can already tell how beefy this new suspension is going to be. |
Dave Dinsmore mocks up the lower arm to the truck to estimate how much he will need to extend the CV-shafts and tie rods. As we went to press the guys at JD Fab were still trying to decide on what to make the new upper A-arm out of...but last we heard, they were leaning toward machined aluminum. | 
Speaking of aluminum, we've got some 4.56 or 4.88 gears and a Tractech Truetrac planned for the front 8.8-inch differential. How well will this axle hold up to 37-inch tires and lots of throttle? We have no idea. But we plan to find out! | 
The rear axle is still a mystery too. The 9 3/4-inch ring gear is as large as a Dana 60, but the shafts are only 34-spline in this Visteon unit, versus 35-spline in some 60s. Our original plan was to swap in a Dana axle in order to run a Detroit Locker, but time constraints dictate that we regear the original axle and run it for now with the factory limited slip. Again, we'll let you know how well it holds up. |