Ford 9 in. 31 Spline Spool HD Case Third Member Assembly

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MPN: 1-215-009 UPC: 840136500896
Available Extended Warranty Eligible
$1,320.00 to $1,405.00

Build to Order


Speedmaster Ford 9 in. third member assemblies are designed to help you get that horsepower to the ground. They include aluminumn thru-bolt design center section, as well as our famous TorqueWorm LSD differential, 1350 series yoke, daytona pinion support, and gear ratio. Whether you're assembling a daily driver, street rod, or race car, Speedamster's third member assemblies will provide the durability that your vehicle deserves.


Part Number:1-215-009
Part Type:Third Member Complete Assembly
Product Line:Standard-Nose Case
Case Style:Ford 9"
Case Material:Aluminum
Main Cap Material:Aluminum
Main Cap Retention Style:Bolt
Carrier Bearing Diameter (in):3.250 in.
Pinion Support Bolt Quantity:10
Standard Pinion Location:Yes
Ring Gear Load Bolt:No
Ring and Pinion Included:Yes
Ring and Pinion Ratio:All Ratios Available
Yoke Included:Yes
Yoke Style:1350 Series
Bearings Included:Yes
Carrier Type:Full Spool.
Quantity:Sold individually.
Notes:Select desired gear ratio.
CalculatorGear Ratio Calculator


HD vs HD Pro

CASE: Our aluminium cases are made from A356-T6 aluminium, our bearing caps are one-piece billet, with a through bolt design and extra material is added to the bearing caps. These cases are offered in 3.250" bearing diameter to accommodate 28, 31 and 35-spline carriers and spools. These extras truly make this Aluminium case the ultimate Ford 9" case, rated to 850 horsepower.  All our aluminium third members come with 12 point through bolts and a billet pinion support, which gives us an advantage over our competition.  


The lightweight SPOOL gives you the traction you need by locking the axle shafts together, forcing your rear tires to turn at the same speed. They"re CNC-machined from forged chromoly steel to provide a more rigid ring gear mounting. This eliminates gear failure caused by case deflection or differential side-gear failure.


The GEARSETS used are HI-PERFORMANCE 8620 Chrome-Nickel-Moly Steel. CNC machined from high-quality forgings to our exacting specifications and then heat-treated to obtain high impact and durability. Then lapped to allow for correct tooth contact and smoothness and for use in the performance market. The 8620 Gearset has proven itself in all forms of motorsport over the past 30 years.  


YOKE: Speedmaster TDS  Billet yokes are a long style unit fully CNC machined to our specifications.


ASSEMBLY: Assembly has been carried out by the Speedmasterª TDS differential team. Quality is assured with 40 years of experience in the Differential Industry and full involvement in all forms of motorsport from V8 SUPERCAR To Group 1 Drag Racing. Our Technicians are on hand to discuss your differential requirements, questions, and upgrades.  


NOTE: These 3rd members are to be used with a mineral-based oil of a range of EP140 Extreme pressure at a minimum, NO split grades eg. 85/140 (These are not recommended), failure to use the correct oil can result in gear damage, noise and may void your warranty.

Brand Information

Speedmaster has become a leader in its field, built on a long term consistency of being a specialist in aftermarket automotive components. The team has shared all the finest moments in the numerous accolades for its people, its products, and its approach. Speedmaster is also one of the rare companies to produce its own products, where majority items are entirely developed and manufactured in its workshops. The ultimate token of precision, Speedmaster is the world’s only major parts manufacturer to equip cars from Standard replacement to Top Fuel Dragsters.Â

In 1979, the company was founded with Pete’s Performance, which was a small speed workshop. It began by building engines for customers as a hobby, and it has now grown to include selling, assembling, manufacturing and racing high performance engine parts. Over the years, the company has grown into a worldwide high performance powerhouse. Growing from a one-man bricks-and-mortar business; to now a supply chain in which en

Prop 65 Warning

This product may contain chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm.

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