Ford 9 Inch Third Member Assembly, Full Spool, 31-Spline

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 For Proper Ring Gear Teeth Pattern

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. 

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. 

Note - Speedway Motors Differential 3rd members come with a 1310 Universal Joint (U-Joint) series yoke. No other Yoke size options are available. 

1310 series U-Joint and Bearing Cap Reatainers Not Included - Sold Seperatly

Gear units are built from long wearing, tough 8620 cold-rolled steel. We offer lightened gear assemblies from 5.29:1 to 6.50:1, select the "L" option (example: 529L) from the gear ratio selection.

Variety of Spool Options 

A variety of spools are available, in gearing from 3.50:1 to 7.33:1. Our CNC machined full spools are stronger than mini spools and available in standard, lite and mega-lite configurations: 

• Standard (STD) full spools are CNC-machined and built for the strip and high-horsepower/torque applications when the ultimate in durability to handle high-traction power is needed. Weight 8 lbs.
• Mega-lite (MEGA) full spools are great for lower traction applications such as dirt racing, lowering your rotating weight, reducing your time to peak RPM and reducing unsprung mass. At just 5.49 lbs., these spools are nearly as light as aluminum but have the strength of machined steel
• Lite (LITE) full spools are a good combination of weight reduction and CNC-machined steel durability, and weigh only 6.1 lbs. 

Proven Reliability

We race what we sell. Our third member units are the go-to choice for our own rides and racecars 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.

Features

• 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 
• 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
• Full spools available in standard, light and mega-lite configurations
• Gear units built of long-wearing 8620 cold-rolled steel, lightened gear options available
• 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

Third Members with Spool type differentials are for race or off road use only. They are not suitable for street use. 

910-48343 Instructions (PDF)