Description: Hand-assembled by our trained technicians for an unbeatable combination of quality and value, Precision assembly for the correct backlash, preload, and proper amount of pinion shims to ensure the correct pattern on the ring gear teeth, Ring and pinion gears of 8620 cold-rolled steel for long wear, Nodular iron housing is stronger than OEM “gray” iron and has 4 lbs of additional reinforcement, Helical-gear differential gives positive traction without the noise of a full locker Ford 9 Inch Helical Gear Posi 3rd Member Assembly, 31 Spl, 3.89 Sku # 91049349-31-389 Mfr. Part # 91049349-31-389 Condition New Brand Speedway Motors Sold Each Details Info 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. Our gears use use cold-rolled 8620 steel, known for its long-wear and 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. 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 - Helical-Gear Style Differential Our helical style limited-slip differential works with any factory Ford 9 inch differential case, gear, axles and bearings. The helical-gear design gives quiet operation, with no clicking when disengaging for corners. While under normal conditions the helical-gear style performs like an open differential, when required the differential automatically transfers torque to the wheel with the highest traction. Smooth power transfer is unnoticed by the driver. When you want the traction benefits of a limited slip differential in your Ford 9 inch rearend without the expense and noise of a full-locker unit, our helical style differentials are just the ticket. Proven Reliability 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. 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 Ring and pinion gears of 8620 cold-rolled steel for long wear 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 Helical gear differential gives positive traction without the noise of a full locker 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 Choose gear ratio - 3.25, 3.50, 3.70, 3.89, 4.11, or 4.56 Choose axle shaft spline count - 28 or 31 splines Charts (PDF) Installation Tips Upon receipt and unboxing of your newly purchased 3rd member, prior to installation, it is recommended that the unit be prepped for installation by cleaning the surface of the unit with a form of cleaner such as aerosol brake cleaner and an air hose/compressed air. This is a normal step in your installation process, and this will properly and sufficiently remove any packaging remnants from the carry case / carry case hardware that may be found to adhered to the 3rd member surface upon receipt. 1310 series U-Joint and Bearing Cap Reatainers Not Included - Sold Seperatly 1310 Series U-Joint Measurments: Yoke Width 3-7/32" Cap Diameter 1.062" Recomended 1310 Universal Joint (U-Joint): Speedway 1310 Series Chevy to Chevy U-Joint - Part Number Dana Spicer 5-153X HD Greasable Cross U-Joint Chevy 1310 Series - Part Number Heavy Duty Greasable Cross U-Joint, 1310 and Driveshaft U-Bolts - Part Number Recomended U-Joint Bolts/Retainers: Universal Drive Shaft U-Bolts, 1-1/16 Inch Cap - Part Number Fast Shafts BBSK-10 Billet U-Bolt Strap Kit, 1-1/16 Inch - Part Number Moroso U-Joint Girdle - Part Number Specs Sold in Quantity Each Gear Material Steel Ring Gear Weight Standard Differential Type Limited Slip Spool Weight Standard Yoke U-Joint Series 1310 Axle Splines 31 Yoke Width 3-7/32" U-Joint Cap Size 1-1/16" Gear Ratio 3.89:1 Yoke Included Yes Housing Material Nodular Iron Carrier Style Gear Style Posi MFG. Part # 91049349-31-389 Ring and Pinion Included Yes Related Items / Suggested Parts 9 Inch Ford Rearend Axle Housing 3rd Member Pumpkin Gasket Tech Support We're here to help before and after your purchase. If you have a question or need assistance with one of our products, please contact us through eBay Messaging and a knowledgeable Speedway Motors team member will be happy to help. About Speedway Motors is America’s Oldest Speed Shop® and has been a trusted source for specialty rodding and racing products and friendly expert advice for more than 73 years. Founded in 1952 by “Speedy” Bill Smith – a racer and street rodder himself – Speedway has grown from a one-man operation to become the world’s largest manufacturer, distributor and retailer of street rod and racing products. Our industry-leading fast delivery is the result of same-day shipping from our state-of-the-art, centrally located 500,000 sq. ft. headquarters. Speedway’s size offers customers unmatched product selection and low pricing, while our excellent technical support and customer service have made us a recognized leader in the rodding and racing industries.
Price: 1009.99 USD
Location: Lincoln, Nebraska
End Time: 2025-01-27T22:13:56.000Z
Shipping Cost: 0 USD
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Item Specifics
Return shipping will be paid by: Buyer
Returns Accepted: Returns Accepted
Item must be returned within: 60 Days
Refund will be given as: Money Back
Return policy details:
Brand: Speedway Motors
Type: Differential Third Members
Manufacturer Part Number: 91049349-31-389
Item Length: 18.00
Item Width: 14.300
California Prop 65 Warning: True