When looking for an axle upgrade for our project we decided the well-known and popular Ford 9-Inch would be perfect. There are a few options when it comes to upgrading to a 9-Inch: We could have gone with a junkyard unit or maybe one from someone else's project that never made it (the Internet is great for that), but after looking at price differences and measuring what width the housing needed to be, we decided starting with a new F-9 fabricated housing from Currie Enterprises would be the best and most financially wise decision we could make, since the cost is not much more than a "normal" 9-Inch housing and will ensure we won't be spending any extra money for axle mods on secondhand equipment.
After we determined what housing we were going to run, the next step was what gears and differential we were going to stuff in the Currie F-9. We called up Superior Axle & Gear, and they set up our third member with 4.86 gears and a Detroit Locker. With the specs of the housing, our proper measurements, and third member in hand, we headed to Currie Enterprises' impressive facility in Corona, California, to see how they build one of these burly F-9 axles.
Step By Step
1. The first step in building the fabricated 9-Inch housing was cutting the 3x0.250-inch axletubes to length. A bandsaw is used for a straight and precise cut.
2. Before the axle ends can be fitted to the axletube, the inside must be machined. This allows for a snug and flush fit as well as added strength.
3. With the axletube machined, the end fits perfectly. Notice the beveled edge on both pieces, allowing for greater penetration when they are welded on.
4. After the axletubes are cut and machined they are placed into a jig with the 3/16-inch-thick centersection, where the measurements are double-checked and the axle is tack-welded together.
5. Before the welding process begins the inspection hole is drilled.
6. The axle assembly is welded by hand, starting with the axletubes to the centersection, including the bulkhead.
7. The inspection bung is TIG welded to the centersection, for a clean appearance.
8. During the welding process high heat can lead to warping of the axle. To eliminate this, the welded axle is placed into a press and straightened back out.
9. The massive truss adds an immense amount of strength to an axle that is already strong, giving us an extra layer of protection. Since the axle being built is for a leaf-spring truck, spring perches are added, along with double plating where the U-bolts go through.
10. With the axle completely welded, it’s apparent that rigidity is greatly increased with the truss. A coat of paint is applied to protect it from rusting, and the assembly can begin.
11. The axleshafts were drilled for our 5x4.5 bolt pattern. The holes are then deburred for a clean and smooth install of the axle studs.
12. The splines are cut on a CNC machine for a precise fit into the Detroit Locker. Notice the shaft doesn’t neck down in size prior to where the splines start—this promotes congruent strength throughout the entire shaft.
13. With the axleshafts drilled and the splines cut, the backing plates were installed and the small Torino-style bearings were pressed on.
14. After the gasket and silicone were applied to the axle, the third member from Superior Axle & Gear, stuffed with 4.86 gears and a Detroit Locker, was dropped into place.
15. With the Wilwood backing plate and parking brake installed, the axleshaft can be inserted into the housing.
16. To complete the axleshaft install, the backing plate bolts are torqued to spec, ensuring we won’t have any loosening problems after hitting some fast desert two-tracks.
17. Installing the Wilwood calipers completes the brake system and ensures we will have plenty of stopping power for this axle.
18. Looking at the completed Fabricated 9-Inch axle you can really get a sense of how much stronger this is than some old F-150 axle. The axle is given a final inspection before delivery to ensure everything is correct, and now it’s ready for our project!