Ford 9 Inch Clutch-Style Posi Differential Premium Third Members
Ford 9", Limited Slip Differential Type, 1310 Yoke U-Joint Series
As featured on Classic Truck’s Week to Wicked. Watch the transformation here!
Assembled by Professionals
Hand-assembled by trained experts in-house, our Ford 9-inch third members are built from quality components with an exact step-by-step process. We bring this combination of precision assembly and quality components to you at a price that can’t be beat. We trust these third members so much, they’re the go-to choice for our own rides, from the street to the track.
Tough, Nodular Iron Center Section
Our Ford 9 Inch Nodular Iron Third Member Center Section Carrier starts with a NEW casting with over 4 lbs. of additional material in critical areas. Nodular (ductile) iron is much more resistant to fracturing than OEM “gray” iron. Extra ribbing reinforces the case and rearmost pinion support (pilot bearing).
Thick, forged steel bearing caps surround the carrier bearings, all securely held in place with precision Grade 8 cap screws. The improvements continue with rugged billet steel adjuster nuts and heavy-duty keepers to ensure your ring gear settings are maintained. All mounting surfaces are precision machined to ensure a consistent, flat surface for a positive gasket seal (no more leaks on your shop floor). An oil fill plug is included.
Precision Assembled with Yukon Gears
Getting a proper pattern on the ring gear teeth is crucial. Our time-proven, step-by-step process ensures the correct backlash, preload, and proper amount of pinion shims to ensure the correct pattern on the ring gear teeth.
Our Premium gear third members are made with a tough-as-nails 10-bolt Yukon gear set, premium finished to reduce friction and heat, to give a long life and exceptional durability.
To ensure a proper gear pattern, we use a stronger “Daytona” style pinion bearing support to maintain that critical pinion depth setting. Stronger due to its larger bearings, our Daytona pinion support also uses the spacer-and-shim setup to maintain critical pinion depth settings under high load, unlike traditional crush sleeves which often compress further, take out your preload and lead to failure. With solid bearing spacers and the proper shims, we eliminate this problem and make setting preload easy and repeatable during installation, service and gear changes. Since preload is already set, simply torque the pinion nut to 160 ft./lbs. and you’re good to go. The pinion gear is connected to our new, forged steel “Ford short”, 1310-type pinion yoke.
Clutch-Style Posi Differential with Proven Performance
Our clutch-style posi differential gives you maximum traction. Based on the original limited-slip designs of the OEMs, these differential units provide the added benefits of experience over millions of miles and decades of proven reliability. A clutch-style operation means no clicking around corners and our posis feature heat-treated spider gears in a forged steel case. We’ve taken this posi to the next step in performance with increased clutch pressure and holding power, suiting it well for heavy-duty street car applications.
This differential has performed well in our Week to Wicked 1952 Chevy Truck, handling the job of transferring a 430 HP GM Performance LS3 to the ground.
- Clutch style, spider gear differential = proven reliability
- Spring-loaded clutch pack with improved grip over OEM designs
- Ideal for street tires and medium horsepower applications
- Housed in a Fully Machined, Reinforced Forged Steel Case
We run what we sell. Our third member units are the go-to choice for our own rides and we have built these units to last with high quality hardware and components. Tapered steel roller bearings minimize friction, better handle thrust loads and increase load carrying capacity. The ring gears are assembled with Grade 9 bolts with a tensile strength of 180,000 psi, a 15% increase over Grade 8 hardware. Heavy duty Grade 8 carrier cap bolts, a lock-style pinion nut with pre-applied Loctite and high-quality grade 5 pinion support bolts make our third member near-bulletproof.
Units include a Viton® pinion seal providing long lasting oil and chemical resistance. This seal retains elasticity up to 399°F (204°C) and intermittently up to 600°F (316°C) This high temp seal helps eliminate pinion leaks, reduces maintenance and keeps the third member properly lubricated. A carrier-to-housing gasket is available separately.
Our hand-assembled Ford 9 inch third member assemblies are made-to-order. We keep a supply of the most popular gears in stock, with most units built within 2-3 days. Our third-member units are shipped in a durable, reusable poly storage case, perfect for keeping multiple gear sets stored and ready for the track.
- Hand-assembled by our trained technicians for an unbeatable combination of quality and value
- Track-tested durability in our own cars – we race what we sell
- Precision assembly for the correct backlash, preload, and proper amount of pinion shims to ensure the correct pattern on the ring gear teeth
- Yukon gears with premium finish reduces friction, heat and provides for long wear
- Made to order, normal build time is 2-3 days with most common gear combinations in stock
- Nodular iron housing is stronger than OEM “gray” iron and has 4 lbs of additional reinforcement
- Large bearing “Daytona” style pinion bearing supports for strength and reliability
- Spacer and shim setup maintains critical pinion depth settings and easier to service than traditional crush sleeves
- Clutch style positraction differential gives limited slip performance and quiet operation (no gears clicking!)
- Ring gears assembled with Grade 9 hardware, 15% stronger in tensile strength than Grade 8
- Viton® pinion seal, resistant to chemicals and high temperatures
- Grade 8 Carrier cap bolts
- Lock-style pinion nut with pre-applied Loctite®
- Grade 5 pinion support bolts
- Includes form fitted, reusable red poly storage case
Gear lube recommendations :
910-44090 - For street and every day driving under normal conditions
910-44140 - For extreme duty, towing or very hot climates
No warranty is offered or made for durability or specific performance. No warranty is offered for commercial, off-road, street performance, or racing use.
- Get FREE shipping when your order includes this item and exceeds $99! Ground shipping only in the contiguous US.
- This item 91051345 is made to order. It will be shipped from our warehouse when it is produced.
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Q & A
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Lucas P. explains how to choose the correct part for a Ford 9" third member build in order to achieve a bulletproof rear. You will find specific recommended parts to use from Speedway Motors.
A brief overview of the steps Speedway Motors takes to ensure you get a quality differential.
In this Tech Tip, John responds to a customer looking to upgrade the 8” stock differential in his Cougar to a 9” open diff.