Written By: Jake Headlee
The Rod Authority ’36 Ford Project needs to have a solid, reliable rearend that compliments a classic yet unique style while still being strong enough to support the potential of big power. Currie Enterprises offers the perfect blend with their Polished Aluminum Street Rod 9-inch housing.
We spent the day with the pros at Currie to walk through a complete build of their Aluminum Street Rod 9-inch rear (Part #CE-2011s) to give you the ins and outs of what goes into building these units from scratch. From high-end quality materials to being completely custom built in-house, it’s easy to see why these rearends are chosen time and again for both performance and street rod builds.
Currie Polished Aluminum Street Rod 9-inch
Part #: CE-2011S
- 206T6 cast aluminum housing center with fins and the Currie Enterprises logo
- 3-x .250-inch wall tubes
- Small, early large, or late large bearing style housing ends
- Custom-built to customer width and pinion offset specs
- All third member studs installed
- Also includes third member gasket, nut, and washer kit
- Dense grade aluminum that polishes up nicely (Offered polish service as Part # CE-0111P)
During a time when quick-change differentials were all the craze for the weekend hot rodders, the Curries set out to build a strong, sexy and reliable street rod differential housing that would be different than the others. Their goal was to build a rearend housing that didn’t have the propensity to be noisy or leak easily.
And for those very reasons, the popularity of this new Currie Street Rod differential grew extensively and even began to spill outside of the street rod markets. Pike’s Peak racers have been known to pick them up for their race cars to take advantage of the high strength and minimum of 13-pound weight savings when compared to other differentials.
“Our extensive amount of components offered really sets us apart, allowing the customer to build a unit that fits their application and budget perfectly,” shared Brian Shephard, Marketing Director of the Corona, California based Currie Enterprises.
The Currie sales/tech team engages their customers in an extensive interview process to learn as many details about the intended vehicle the differential will be going into as Shephard explains, “We work with each customer so we can suggest the proper components to the customer so that they get a unit that will stand the test of time for their particular application and use.” Working with each customer individually allows the techs to match up the exact components that will allow for ultimate reliability and longevity.
Currie has the original factory bracket location specifications and new reproduction brackets for many common and popular vehicles. This allows for a crate assembly that is ready to easily bolt into your vehicle using your factory type suspension.
Our extensive amount of components offered really sets us apart, allowing the customer to build a unit that fits their application and budget perfectly. -Brian Shephard
For the aluminum center section and many of their other rearend options, Currie can also easily set up non-triangulated aftermarket suspension system brackets per the suspension manufacturer’s specifications so long as the brackets and bracket installation instructions are provided.
For most hot rods or custom street rods, this housing setup is ideal to build your own axle tabs and suspension platform, as we did to setup the rearend for our TCI Engineering chassis and suspension (stay tuned for the installation and build).
Built from scratch right here in Corona, California – Currie focuses not just on quality components and R&D, but also on quality people. As a family owned business, this same passion runs through each and every member of the Currie team.
Follow along as we delve into the assembly of this truly custom-built differential, built specifically for the Rod Authority ’36 Ford Project: Flat Out build.
Features & Benefits // The Why
Whether you’re building a custom hot rod, classic resto-mod, or full on street rod from the ground up, component selection makes all the difference in the outcome of every build. When selecting a rearend that will mate with your drivetrain for optimum performance there are a few key factors to consider.
Quality components will ensure that you won’t get stranded on the track or at the next show. Selecting the right pieces of the puzzle will not only offer the perfect blend of style and performance, but will ensure comfortable drivability for years to come.
Working with Brian Shephard and the tech experts at Currie we were able to select the right options for our use. We wanted something that would handle the upgraded horsepower of a Modular Coyote swap, while still bringing the classic looks needed to tie it all together.
What it boiled down to is we need something that’s capable of reliable daily driving, while being able to handle what we throw at it on the track. With that recipe in-hand, here are the options that Currie recommended for our Aluminum Street Rod 9-inch rear.
- CE-2011S – Currie aluminum 9-inch housing
- CE-0016 – 28-spline axle package
- CE-0111P – Polished aluminum center section
- Ratio: 3.50S
Down And Dirty // The Build
The Currie Polished Aluminum Street Rod 9-inch Housing is built and cast from 206T6 aluminum for superior strength. The first part of the housing build involves heating this cast center section to 450 degrees to allow the openings to expand.
Here you can see the Currie fabricators pulling the housing center out of the heating oven after it has been heated to 450 degrees to expand it to allow the tubes to drop in for a permanent seal.
Sections of 3x.250-inch wall tubing is cut to length, machined and siliconed prior to being fitted into the super heated housing case. As the case cools, the tubes become permanently pressed in.
After the tubes are inserted, six pairs of evenly clocked holes are drilled and threaded into the housing and tube for stainless steel Allen head security bolts to eliminate any slight possibility of the combination separating once those bolts are securely tightened.
The 3x.250-inch wall D.O.M. steel axle tube O.D. is precision machined for a perfect fit into the machined bore in the aluminum housing center. Tubes are machined to remove any surface variations so they seal perfectly to the machined bore. With the heated housing center pulled out of the oven, black rtv is applied to the end of the tube and the tube being installed into the heated casting.
For this application 9+ Torino bearings were selected to support the semi-floating axle. The Late Model Torino style bearing set up has been accepted as the industry standard for axle bearings due to its reliability and popularity. Early large bearing set ups are really only used these days if a customer is trying to reuse existing brakes that are designed to fit the early ends.
Measure twice and cut/weld once. Here the housing ends are being installed to exact specs per the build sheet.
With the tubes in place, a dummy third member case is installed to support Currie’s alignment bar. The alignment bar allows them to install the housing ends true to the third member’s carrier bearings. Measurements are checked several times to ensure accuracy.
Every part of the Aluminum Street Rod differential is hand-built in the Currie facility right here in the good ol’ US of A – which is quite fitting for a classic project with a modern spin. A 9+ nodular iron third member case and 9+ nodular iron pinion support have been employed to secure the Midwest Motive gears and Ford 28-spline open differential.
The pinion support is installed with “set up” bolts so that the pattern can be checked. After the pattern is run, the support may or may not need to be removed to install more or less shim(s) between the support and the case. After the correct shimming is attained, the black set up bolts will be removed and the new gold bolts, that are pre-loctited, are installed.
Diving deeper into the internals and piecing our rearend together a carrier cap is fitted down over the threads of the spanner nut and the spanner nuts are adjusted with a spanner nut wrench to adjust gear backlash. The semi-floating/drop out axle arrangement makes for a trustworthy unit that has been tried and true.
The carrier cap is fitted down over the threads of the spanner nut and the spanner nuts are adjusted to set the gear backlash. A dial indicator is mounted on case and then adjusted to the ring gear measuring backlash for a precision long lasting set up.
As you can see, the differential receives careful attention from start to finish. Correct gear pattern and pinion backlash can make a world of difference with the longevity of your rearend. An incorrectly patterned gear set will generate unwanted noises as well as prematurely wear the components leading to an early demise.
Lucky for us, Currie Enterprises has installed countless gear sets in many different types of differentials through the years.
Custom-built specifically for this build, 1541 induction heat treated forged alloy steel axle shafts are precisely machined on both ends, and splined to the specified spline count – in this case, 28-spline axles were chosen for this particular build.
After heat treating, grade-8 lug studs are added in the bolt pattern of choice. A wide range of bolt patterns are available, even two patterns can be drilled into the flange if you feel you might change bolt patterns in the future. The T-bolts installed are with flat washers to temporarily retain the bearings into the housing. Customer’s brakes will retain the bearings once the brakes are installed. For this application we will be going with a custom SS4+ setup from Baer (stay tuned for more on that install.)
Right: Finalized 3rd member being dropped into place. Left: T-bolts installed with flat washers to temporarily retain the bearings into the housing. The Baer brakes will retain the bearings once the brakes are installed.
More To Come // Stay Tuned
After witnessing the complete assembly of the rearend and differential firsthand, it’s easy to see why this unit is so popular among hot rod and performance enthusiasts alike. A very well thought out and extremely reliable rear – this Aluminum 9-inch Street Rod is the perfect addition to Project Flat Out.
Currie means business, and with quality products built in California for valued customers world wide, now we know why! More information on this and other custom hot rod rearend options can be found online at the Currie Enterprises website or check out their Facebook page for more project updates.
Stay tuned as we add all of the TCI Engineering custom suspension brackets and slap this bad boy under the TCI Engineering Chassis for our Rod Authority 1936 Ford Project build.