Yukon Ford 9" Steel Spool - 40 Spline
YUKYP FSF9-40
The Yukon Ford 9" Steel Full Spool is a simple, strong, and cost-effective solution for achieving 100% axle lockup in dedicated off-road, rock crawling, mud racing, drag racing, and competition vehicles. Unlike a differential or locker, a spool permanently locks both axle shafts together, ensuring equal torque is delivered to both wheels at all times.
Manufactured from high-strength 8620 steel and heat-treated for maximum durability, this spool is designed to handle the severe shock loads generated by large tires, high horsepower, aggressive launches, and extreme off-road conditions. Designed specifically for Ford 9 inch differentials using 40 spline axle shafts, this spool is an excellent choice for competition vehicles where maximum traction and drivetrain strength are more important than street manners.
Includes:
- Ford 9" steel full spool
- 40 spline configuration
- Direct carrier replacement design
Specifications
- Brand: Yukon Gear & Axle
- Part Number: YP FSF9-40
- Product Type: Full spool
- Application: Ford 9 inch differential
- Spline Count: 40 spline
- Material: 8620 heat-treated steel
- Traction Type: Permanent 100% lockup
- Carrier Replacement: Yes
- Street Legal Use: Not recommended
- Quantity: Sold individually
Fitment
|
Year |
Make |
Model |
Differential |
|
1966-1986 |
Ford |
Bronco |
Ford 9 Inch |
|
1969-1980 |
Ford |
E-100, E-150, E-200, E-250 Econoline |
Ford 9 Inch |
|
1957-1987 |
Ford |
F-100, F-150 |
Ford 9 Inch |
|
1957-1970 |
Ford |
Fairlane |
Ford 9 Inch |
|
1960-1970 |
Ford |
Falcon |
Ford 9 Inch |
|
1959-1974 |
Ford |
Galaxie, Galaxie 500 |
Ford 9 Inch |
|
1972-1976 |
Ford |
Gran Torino |
Ford 9 Inch |
|
1975-1979 |
Ford |
Granada |
Ford 9 Inch |
|
1965-1979 |
Ford |
LTD |
Ford 9 Inch |
|
1970-1977 |
Ford |
Maverick |
Ford 9 Inch |
|
1965-1973 |
Ford |
Mustang |
Ford 9 Inch |
|
1957-1979 |
Ford |
Ranchero |
Ford 9 Inch |
|
1955-1979 |
Ford |
Thunderbird |
Ford 9 Inch |
|
1958-1979 |
Lincoln |
Continental |
Ford 9 Inch |
|
1968-1971 |
Lincoln |
Mark III |
Ford 9 Inch |
|
1964-1977 |
Mercury |
Comet |
Ford 9 Inch |
|
1967-1979 |
Mercury |
Cougar |
Ford 9 Inch |
|
1975-1980 |
Mercury |
Grand Marquis |
Ford 9 Inch |
Fitment Notes
- Fits Ford 9 inch differentials configured with 40 spline axle shafts
- Replaces the differential carrier assembly
- Compatible with many aftermarket Ford 9 inch third members
- Verify spline count, carrier configuration, and housing setup before ordering
Tech Insight
1. What is a full spool?
A full spool permanently locks both axle shafts together, providing 100% torque to both wheels at all times with no differential action.
2. Is a spool stronger than a locker?
Yes. Because a spool contains no moving locking components, it is generally stronger and more reliable than most lockers in extreme racing and off-road applications.
3. Can I drive a spool on the street?
A spool is not recommended for street-driven vehicles. Since both wheels remain locked together, tire scrub, increased tire wear, and poor street handling characteristics will occur.
4. What spline count does this spool require?
This spool is designed specifically for 40 spline axle shafts.
5. Is a spool good for rock crawling?
Many competition rock crawlers, drag cars, mud racers, and dedicated off-road vehicles use spools because they provide constant traction and maximum drivetrain strength.
