A common issue with the Ford 9-inch is that it can be difficult to choose the correct parts to build per your vehicle’s needs. You have to ask yourself several questions. What do I want to do with my vehicle? How do I want to drive it? Is my teenager going to drive it on occasion? Or, are you going to drive it like you are a teen? These are all legitimate questions when building a project truck. Growing up, my dad always taught me to overbuild everything; this way 99-percent of any potential issues would be squashed by overkill. Upgrading or overbuilding can be especially true when building a custom vehicle. With my project truck, I want to drive heck out of it and still be able take it out for a Sunday cruise or hit the open highway. Twenty years ago, driving a truck like a car would have been a tall order for any stock rearend—let alone that most aftermarket parts companies lacked demand for it.
Things have changed for the better. Aftermarket companies like Wilwood, Detroit Locker, Speedway Engineering, and Currie Enterprises have looked toward the next generation of vehicle builders, who not only want to go fast in a straight line but also want to toss in a few curves with hard stopping. Say what you will about the surge of performance-associated builds, but the trend will be here for at least the next few years. As a member of the automotive media, I feel it’s my obligation to share what I have learned from the much smarter men and women of the performance aftermarket. If said companies/builders didn’t push the limits of their vehicles, then we wouldn’t have the quality of products they offer today. Another example would be the progression of the Mustang and Corvette over the last 40-plus years. The knowledge gained from racing, driving, and long-haul testing these vehicles is then passed down to less expensive vehicles, providing a better product for the end user. Classic Trucks represents vehicles of our past, but in the same respect it is important to recognize the future.
Let’s start things out with...
Let’s start things out with the housing ends. The Currie Enterprises 9-Plus late-model (Torino-styled) large bearing ends are pictured at the left. Center is the Speedway Engineering floater hub spindle—similar to what you would find on a NASCAR vehicle or in some heavy-duty pickup trucks. Pictured on the right are the early-model Ford large bearing housing ends. The machined Currie axle ends will accept the larger tapered bearings. Both Currie and the Speedway ends are CNC machined. The Currie ends will accept stock disc/drum brakes along with larger kits like Wilwood in the main photo. The Speedway spindle is nothing new to the market, but Wilwood recently adapted the use of a parking brake to the Speedway floater hub. This makes for a unique setup that I think will be seen on show vehicles and Pro Touring builds alike.
The Speedway floater hub works...
The Speedway floater hub works by placing the bearing on the outside of the housing and supports the vehicle’s weight via two large-tapered bearings and Speedway hub. A 24-spline straight-cut axle then drives the vehicle on the hub side and 28-, 31-, or 35-spline inner depending on your carrier’s spline. This style works extremely well for autocross, road course, and daily driving because the weight of the vehicle is taken off the axle and placed on the bearings, causing less strain on the rearend.
The top left bearing is the...
The top left bearing is the stock replacement for a Ford axle and housing. Notice how small the bearing is compared to the other two. The bottom bearing is a large-style 9-inch bearing that is used for a 31-spline axle with upgraded ends. The larger bottom bearing is used in street-driven vehicles as well as more aggressive driving, like drag racing or autocross. The bearing at the top right is a huge bearing used for drag racing and is able to fit the giant 35-spline axles that support large displacement motors.
From left to right: stock...
From left to right: stock Ford 28-spline axle, 30-spline for GM 12-bolt; Dana 44 the 31-spline, which is the most common for the hot rod market and can handle around 700 hp; 33-spline for drag race-only spool; heavy-duty 35-spline axles for high-horsepower motors from 700 to 1,200; and the 40-spline full-on drag axle found in Top Fuel cars ECT.
Currie axle ends can be drilled...
Currie axle ends can be drilled by them to match most applications. The axles can also be drilled in multi-lug patterns so you can change your mind down the road on a Ford or a Chevy lug pattern.
Wide drums, disc, or big-brake...
Wide drums, disc, or big-brake upgrades can be adapted to any kind of housing ends. Ford early and late ends, and Speedway Engineering spindles can be adapted to several styles of brakes, but in my opinion, aftermarket disc brakes like Wilwood’s are the way to go.
Gear cases for the 9-inch...
Gear cases for the 9-inch come in many different applications. For most of the hot rod and truck market, the nine-plus nodular, sportsman and race cases work great. The sportsman case is Currie’s nodular replacement for the now hard to find stock Ford case. You can easily identify the nodular case by the “N” stamped on the outside. The 9-Plus Currie case has been reinforced with extra material and has an extra rib running down the center. The 9-Plus case is also stamped on the outside for easy identification.
Inside the gearcase is what...
Inside the gearcase is what is called the carrier, or the differential. One of the carrier’s jobs is to transfer the engine’s power to the wheels via the gearset and axles. Most important, the carrier allows the left and right wheels to travel at different speeds when turning, in wet conditions, or burnouts. Not all differentials are created equal, that is why Currie and Eaton Detroit have different speeds when touring several different styles of differentials to choose from. From left to right, clutch-type Posi, Detroit locker, Spool, and Truetrac.
Several types of differentials...
Several types of differentials are used in the automotive aftermarket with several different applications. For several different applications, an Eaton Detroit Truetrac limited-slip differential is a good choice. The Eaton Detroit Truetrac has helical gears inside that employ forces to automatically transfer torque to the wheel with the best traction. According to Eaton, the differential is open during normal cruise conditions and as the wheel encounters loss of traction the gear separation force takes effect and transfers torque to the high-traction wheel.
Another option is Currie’s...
Another option is Currie’s Posi limited-slip differential. Similar to the Truetrac but rather than using gears, the limited-slip Posi uses clutch packs. We all know what a manual clutch disc looks like, so visualize several small clutches on the left and right side of the differential that have spring tension on them. The clutches and springs provide a smooth transition between wheel slip around turns and great overall traction for today’s street-driven vehicle.
A pinion support does just...
A pinion support does just that, support the pinion, but it also can house multiple bearing sizes, depending on your ring-and-pinion and axle size. For most applications the 9-Plus standard pinion support and 9-Plus big-bearing support is more than adequate.
Yokes are available in most...
Yokes are available in most common U-joint sizes. From the left side going down is an 1310 short nodular iron, 1310 long nodular iron (1-inch taller), 1330 short nodular iron, 1330 long nodular iron (1-inch taller), 1350 nodular iron, 1350 billet. The 1310, 1330, and 1350 all correspond to U-joint numbers that help the end user fit a driveshaft properly.