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Ford 9-inch Lightweight Aluminum Third Member Assembly (31-Spline)

New, built-to-order Currie 9-inch lightweight aluminum third member set up for 31-spline axles. Options include a choice of differential type, gear ratio, and pinion yoke.


Features:

  • Lightweight Aluminum Case with 3.062 Bore
  • Currie Aluminum Big Bearing (Daytona) Pinion Support
  • Choice of Gear Ratio, Carrier and Pinion Yoke
  • Setup and Assembled by Skilled Professionals

*** SELECT OPTIONS TO BUILD AND PRICE ***

SKU: CE-4028AK
Estimated Lead Time: 2 weeks
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$1,139.00

This lightweight aluminum third member is well suited for vehicles under 3,000 lbs with moderate horsepower and street tires. If you have a heavy vehicle, hi-horsepower, and launch aggressively, the HD-Pro Aluminum 9-inch third member and upgraded 35-spline axles would be better options.

All Currie Ford 9-inch third members are assembled by our in-house experts with decades of rearend setup and assembly experience, so you can trust the finished product.

 

Currie 9-inch Third Member Features:

  Gear Case - Lightweight Strange Aluminum 9-inch gear case weighs just 13.69 lbs. compared to 27 lbs. for an iron case
     
  Pinion Support - Billet aluminum big bearing (Daytona) pinion support features a larger inner pinion bearing for increased strength and oil passageways designed for extended high-speed use
     
9-inch master Bearing Kit   Master Bearing kit - New Timken master bearing kit with seals and solid pinion spacer
     
Assembly labor   Labor - Fully assembled and set up in-house by skilled professionals

 

 

9-inch Third Member Options:

9-inch Ring and Pinion   Gear Ratios – Select from a wide range of ratios. Currie uses only the highest quality Motive Gear Performance® series (Orange box) ring and pinion sets in our 9-inch crate rearends
     
9-inch Limited Slip   Differential Options - Choice of 31-spline helical gear limited slip, automatic locking differential, or a steel spool
     
Billet 1350 Yoke   Pinion Yoke - Choice of 1330 or 1350 short yokes in nodular iron or chromoly
     
Gear Polishing   REM® Isotropic Polishing - Removes surface imperfections created during the gear manufacturing process. Polishing eliminates the need for a break-in period, decreases friction, reduces operating temps, and removes stress risers, to help gears last longer and run quieter

 

 

Differential Options Explained

Trac-Lok – A classic clutch-style limited-slip differential. When the unit is new, the clutches provide a torque bias that applies power to both axles equally under acceleration. When the vehicle goes around a corner, the clutches provide a limited-slip that allows the wheels to spin at different rates. Modern tire grip and high horsepower can easily overpower the clutch bias and cause the unit to behave more like an open differential than a limited-slip. Trak-Loks require special oil additives and periodic maintenance, as everyday driving wears the clutches leading to reduced torque bias.

 

Currie TwinTrac, Truetrac, and Wavetrac - Helical gear limited-slip type differentials (HGLSD). The HGLSD is the modern replacement for the classic clutch-style limited-slip. HGLSDs function like a standard or open differential, allowing one wheel to spin faster or slower as necessary without the noise or stick-slip frequently experienced with clutch-style limited slip or automatic locking differentials. Under acceleration, if a wheel begins to lose traction, the helical gears inside the differential automatically engage, transferring torque to both rear wheels. When the wheels regain traction, the HGLSD seamlessly transition back to functioning as an open differential. Unlike the traditional clutch-type limited-slip, HGLSDs require no special oil additive or maintenance to replace worn and tired clutches. HGLSDs have no wearable parts, require no special oil additive or maintenance, and maintain their as-new functionality for life.

 

ARB Air Locker - The ARB is a selectable locking differential that allows the driver to positively lock or unlock the differential on demand with the flick of a dash-mounted switch. An onboard air compressor (sold separately) is used to apply the locking force. Once locked, the differential behaves like a spool, driving both wheels equally. When unlocked, the locker acts like an open differential, driving only one wheel at a time – usually the wheel with the least traction. The key benefits of the ARB Air Locker are its predictable behavior and legendary strength.

 

Detroit Locker - Automatic locking differential, designed to automatically lock and unlock when torque is applied, in either a forward or reverse direction. When locked, it acts like a spool driving both wheels equally. When coasting or rolling into a corner (no torque applied), the Detroit Locker unlocks and momentarily operates like an open differential permitting the wheels to rotate freely. When torque is applied, exiting the corner, the unit locks and drives both wheels equally. The key benefits of the Detroit Locker are its rugged construction and superb performance. The only negative is that the automatic lock and unlock operation can create a clunking sensation that can be felt and heard in the vehicle.

 

Spool – The spool is the most straightforward and most robust option, but it lacks differential action, as both axles are joined together by the spool's solid center. Spools are not recommended for the street, as they place high twisting loads on the axles, increase tire wear, and negatively impact handling. Spools are typically only used for drag racing applications where straight-line performance is the only concern.

This lightweight aluminum third member is well suited for vehicles under 3,000 lbs with moderate horsepower and street tires. If you have a heavy vehicle, hi-horsepower, and launch aggressively, the HD-Pro Aluminum 9-inch third member and upgraded 35-spline axles would be better options.

All Currie Ford 9-inch third members are assembled by our in-house experts with decades of rearend setup and assembly experience, so you can trust the finished product.

 

Currie 9-inch Third Member Features:

  Gear Case - Lightweight Strange Aluminum 9-inch gear case weighs just 13.69 lbs. compared to 27 lbs. for an iron case
     
  Pinion Support - Billet aluminum big bearing (Daytona) pinion support features a larger inner pinion bearing for increased strength and oil passageways designed for extended high-speed use
     
9-inch master Bearing Kit   Master Bearing kit - New Timken master bearing kit with seals and solid pinion spacer
     
Assembly labor   Labor - Fully assembled and set up in-house by skilled professionals

 

 

9-inch Third Member Options:

9-inch Ring and Pinion   Gear Ratios – Select from a wide range of ratios. Currie uses only the highest quality Motive Gear Performance® series (Orange box) ring and pinion sets in our 9-inch crate rearends
     
9-inch Limited Slip   Differential Options - Choice of 31-spline helical gear limited slip, automatic locking differential, or a steel spool
     
Billet 1350 Yoke   Pinion Yoke - Choice of 1330 or 1350 short yokes in nodular iron or chromoly
     
Gear Polishing   REM® Isotropic Polishing - Removes surface imperfections created during the gear manufacturing process. Polishing eliminates the need for a break-in period, decreases friction, reduces operating temps, and removes stress risers, to help gears last longer and run quieter

 

 

Differential Options Explained

Trac-Lok – A classic clutch-style limited-slip differential. When the unit is new, the clutches provide a torque bias that applies power to both axles equally under acceleration. When the vehicle goes around a corner, the clutches provide a limited-slip that allows the wheels to spin at different rates. Modern tire grip and high horsepower can easily overpower the clutch bias and cause the unit to behave more like an open differential than a limited-slip. Trak-Loks require special oil additives and periodic maintenance, as everyday driving wears the clutches leading to reduced torque bias.

 

Currie TwinTrac, Truetrac, and Wavetrac - Helical gear limited-slip type differentials (HGLSD). The HGLSD is the modern replacement for the classic clutch-style limited-slip. HGLSDs function like a standard or open differential, allowing one wheel to spin faster or slower as necessary without the noise or stick-slip frequently experienced with clutch-style limited slip or automatic locking differentials. Under acceleration, if a wheel begins to lose traction, the helical gears inside the differential automatically engage, transferring torque to both rear wheels. When the wheels regain traction, the HGLSD seamlessly transition back to functioning as an open differential. Unlike the traditional clutch-type limited-slip, HGLSDs require no special oil additive or maintenance to replace worn and tired clutches. HGLSDs have no wearable parts, require no special oil additive or maintenance, and maintain their as-new functionality for life.

 

ARB Air Locker - The ARB is a selectable locking differential that allows the driver to positively lock or unlock the differential on demand with the flick of a dash-mounted switch. An onboard air compressor (sold separately) is used to apply the locking force. Once locked, the differential behaves like a spool, driving both wheels equally. When unlocked, the locker acts like an open differential, driving only one wheel at a time – usually the wheel with the least traction. The key benefits of the ARB Air Locker are its predictable behavior and legendary strength.

 

Detroit Locker - Automatic locking differential, designed to automatically lock and unlock when torque is applied, in either a forward or reverse direction. When locked, it acts like a spool driving both wheels equally. When coasting or rolling into a corner (no torque applied), the Detroit Locker unlocks and momentarily operates like an open differential permitting the wheels to rotate freely. When torque is applied, exiting the corner, the unit locks and drives both wheels equally. The key benefits of the Detroit Locker are its rugged construction and superb performance. The only negative is that the automatic lock and unlock operation can create a clunking sensation that can be felt and heard in the vehicle.

 

Spool – The spool is the most straightforward and most robust option, but it lacks differential action, as both axles are joined together by the spool's solid center. Spools are not recommended for the street, as they place high twisting loads on the axles, increase tire wear, and negatively impact handling. Spools are typically only used for drag racing applications where straight-line performance is the only concern.