Currie Enterprises Fabricated Ford 9 Inch Rear AxlePosted in How To on January 1, 2010 Comment (0)
Everyone likes to brag about their axles. Whether you've custom-built a bulletproof Trophy Truck-style unit or you've simply bolted on a stout differential cover, we're betting that most of you have displayed some axle pride in one way or another. Lately, a number of fabricated/race-style housings have become available to consumers, matching incredible strength and protection with super-cool looks. Once, housings like these were the stuff of dreams (unless you had a lot of dough or welding experience), but now they're easy to get...and no more expensive than many "normal" housings. When we saw that Currie had released their long-awaited new fabricated housing, we bit the bullet and ordered one up for our project Bronco-and it was cheaper than you might think!
A few details about the housing: it features a 3/16-inch-thick Hi-Form 50 steel body, a 3/8-inch-thick third member mounting face, and we had ours outfitted with 3-inch shaft tubes. Unique to this design, the first bend in the housing is centered with the middle line of the axle tube. This allows the bend to be the point of lowest ground clearance, and the flats on the housing to provide maximum ground clearance at up to 20 degrees of pinion angle.
Another unique feature is the welded bulkheads inside the housing that tie the face, the body, and the inner ends of the tubes all together. The 3-inch tubes easily slide in from the outside and require minor grinding to flatten one side of the tube to key it into the inner bulkhead.
Don't let the technical mumbo-jumbo confuse you-the housing is meant to surround traditional 9-inch internals. The design simply enhances the strength, protection, and clearance offered by more conventional housings. Plus, the thing looks amazing-it's definitely an attention-getter. The price of the housing? Incredibly, the base unit retails for $629. A few years ago, a comparable custom housing would have cost many times that amount.
We were lucky enough to have the Currie team build a complete 9-inch axle assembly, using the fabricated housing, and mount it on our project Bronco. Baer supplied some trick disc brakes (a great upgrade from the Bronco's original drums), and we ordered an Eaton Detroit Truetrac limited slip and 4.56 gears from Superior Axle & Gear to complete the package. Now, we've got one of the baddest rearends on the block, and it didn't require a million bucks. Look for photos in future issues of us abusing it accordingly!
Relocating the Speed Sensor
Broncos (and many other vehicles) utilize a tone ring in the rear axle assembly that is calibrated to measure the vehicle's speed. In addition to providing the dashboard speedometer with the info that tells how fast the vehicle is moving, the speed sensor also provides the transmission with the data it needs to determine proper shift points. Since we replaced the entire rear axle assembly with a unit that doesn't have a speed sensor, we needed a solution-otherwise we'd get no speedometer reading and the Bronco's E40D transmission wouldn't know when to shift.
Salvation came in the form of an innovative sensor unit available from Brea Auto Electric. It's a 5 7/8-inch aluminum ring that is mounted around the vehicle's transfer case yoke, paired with a magnetic sensor that is bracketed in place using one of the stock transfer case bolts. The ring has a number of small magnet inserts that are read by the sensor, which is calibrated to judge vehicle speed and send the info to both the tranny and speedo. Problem solved. Brea Auto Electric redesigned the sensor system for this very story, and it's now available.