Differential Cases
Circle Track Differential Cases at JJ Motorsports
House your gears securely with robust differential cases from JJ Motorsports, designed for Ford 9in rear ends in circle track racing. These assembled cases with built-in spools ensure reliable torque distribution, reduced weight options, and easy integration for optimal traction and durability in IMCA, USMTS, late models, modifieds, and street stocks under extreme dirt oval conditions.
Shop trusted brands like PEM for lightweight assembled units with various ratios. Explore related categories such as Circle Track Differentials and Rear End Components for complete rear end solutions or Circle Track Ring and Pinion Gears for gear upgrades.
Top Circle Track Differential Cases
- PEM 9in Gear Full Spool 6.50 Ratio New Center Section CSFS65031 – Differential Case Assembled 6.50 Ratio 31 Spline Steel Spool Natural Ford 9 in Each.
- PEM New Center Section FS 7.00 Ratio 31 Spline L/W CSFS70031LW – Differential Case Assembled 7.00 Ratio 31 Spline Steel Spool Ford 9 in Each.
- PEM New Center Section FS 6.83 Ratio 31 Spline L/W CSFS68331LW – Differential Case Assembled 6.83 Ratio 31 Spline Steel Spool Ford 9 in Each.
Browse our in-stock inventory below with same-day shipping and expert support. Free shipping on orders over $99! Questions? Contact us for fitment advice!
- Product
- Qty in Cart
- Quantity
- Price
- Subtotal
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PEM 9in Gear Full Spool 6.50 Ratio New Center Section CSFS65031
PEM
$718.99A full spool locks both rear wheels together for maximum traction during hard acceleration and cornering, eliminating wheel spin and delivering consistent power to the track. The PEM 9-inch center section with a 6.50 gear ratio is built for serious drag...PEMCSFS65031- SKU:
- PEMCSFS65031
- Availability:
- Ships Same Business Day
- Weight:
- 40.00 LBS
$718.99 -
Ford 9 Inch Third Member Assembly, Full Spool, 31-Spline
J J MOTORSPORTS
$1,025.95If you're building a dedicated drag, circle track, or street strip machine, a full-spool third member delivers the straight-line performance your setup demands. The Ford 9-inch with a locked spool eliminates wheel hop and power loss by ensuring both rear...234-9091- SKU:
- 234-9091
- Availability:
- 1-2 Week Lead Time for Build
- Weight:
- 50.00 LBS
$1,025.95 -
PEM New Center Section FS 7.00 Ratio 31 Spline L/W CSFS70031LW
PEM
$876.99A 7.00 ratio center section transforms your Ford 9-inch differential into a precision tool for high-RPM acceleration and track performance. Whether you're building a dedicated drag setup or maximizing mid-range punch on the strip, this PEM spool delivers...PEMCSFS70031LW- SKU:
- PEMCSFS70031LW
- Availability:
- Ships Same Business Day
- Weight:
- 75.00 LBS
$876.99 -
PEM New Center Section FS 6.83 Ratio 31 Spline L/W CSFS68331LW
PEM
$876.99If you're building a dedicated drag or road-race Ford 9-inch, the PEM center section delivers the gear ratio and lockup characteristics you need for consistent power delivery off the line. This 6.83 ratio spool is engineered for vehicles that demand...PEMCSFS68331LW- SKU:
- PEMCSFS68331LW
- Availability:
- Ships Same Business Day
- Weight:
- 7.00 LBS
$876.99Qty in Cart: 0Quantity:Price:$876.99Subtotal: -
PEM New Center Section FS 6.66 Ratio 31 Spline L/W CSFS66631LW
PEM
$876.99If you're building a high-rpm Ford 9-inch rear end that demands immediate power delivery without hesitation, the PEM New Center Section FS 6.66 Ratio is engineered to eliminate wheel spin and keep both tires driving hard through the corner. The 6.66 gear...PEMCSFS66631LW- SKU:
- PEMCSFS66631LW
- Availability:
- Ships Same Business Day
- Weight:
- 75.00 LBS
$876.99 -
PEM New Center Section FS LW 650 Ratio 31 Spline CSFS65031LW
PEM
$768.95A 6.50 ratio differential is essential for high-RPM acceleration and consistent power delivery on the track or strip. The PEM center section delivers the mechanical lock and durability required for serious racing, eliminating wheel hop and ensuring both...PEMCSFS65031LW- SKU:
- PEMCSFS65031LW
- Availability:
- Ships Same Business Day
- Weight:
- 75.00 LBS
$768.95 -
PEM New Center Section FS LW 583 Ratio 31 Spline CSFS58331LW
PEM
$768.12A locked differential is essential for serious drag racing and off-road performance, and the PEM New Center Section FS LW delivers uncompromising power transfer without the complexity of electronic systems. The 5.83 ratio is engineered for aggressive...PEMCSFS58331LW- SKU:
- PEMCSFS58331LW
- Availability:
- Ships Same Business Day
- Weight:
- 75.00 LBS
$768.12 -
PEM 9in Gear Full Spool 6.33 Ratio New Center Section CSFS63331
PEM
$718.99A full spool differential eliminates wheel spin by locking both rear wheels together, delivering maximum traction off the line—essential for dedicated drag racing, street racing, and high-performance driving where consistency matters. The PEM 9in Gear...PEMCSFS63331- SKU:
- PEMCSFS63331
- Availability:
- Ships Same Business Day
- Weight:
- 70.00 LBS
$718.99 -
PEM 9in Gear Full Spool 6.20 Ratio New Center Section CSFS62031
PEM
$718.99A 6.20 gear ratio spool is essential for high-horsepower applications where you need aggressive acceleration off the line without sacrificing drivability on the street. This PEM unit delivers the strength and precision demanded by serious racers and...PEMCSFS62031- SKU:
- PEMCSFS62031
- Availability:
- Ships Same Business Day
- Weight:
- 42.00 LBS
$718.99 -
PEM 9in Gear Full Spool 5.83 Ratio New Center Section CSFS58331
PEM
$718.99If you're serious about track performance or drag racing, you need a differential that can handle sustained power delivery without slipping. The PEM 9in Gear Full Spool delivers a locked-axle platform with a 5.83 ratio—ideal for acceleration-focused...PEMCSFS58331- SKU:
- PEMCSFS58331
- Availability:
- Ships Same Business Day
- Weight:
- 40.00 LBS
$718.99 -
PEM 9in Gear Full Spool 3.70 Ratio New Center 31 CSFS37031
PEM
$718.99A full spool differential eliminates wheel slip and ensures both rear wheels receive equal power delivery—essential for consistent traction during hard acceleration and cornering. The PEM 9in Gear Full Spool with its proven 3.70 ratio strikes the balance...PEMCSFS37031- SKU:
- PEMCSFS37031
- Availability:
- Ships Same Business Day
- Weight:
- 74.00 LBS
$718.99 -
PEM 9in Gear Full Spool 5.67 Ratio New Center Section CSFS56731
PEM
$718.99A full spool differential eliminates wheel spin and delivers power to both rear wheels simultaneously—essential for drag racing, circle track, and high-traction applications where consistent acceleration matters. The 5.67 ratio is engineered for peak...PEMCSFS56731- SKU:
- PEMCSFS56731
- Availability:
- Ships Same Business Day
- Weight:
- 42.00 LBS
- MFG Part #:
- CSFS56731
$718.99 -
PEM 9in Gear Full Spool 5.43 Ratio New Center Section CSFS54331
PEM
$718.99If you're serious about drag racing or high-performance street applications, a full spool delivers the straight-line acceleration and launch consistency you need—no wheel spin, no power loss to differentiation. The PEM 9-inch with a 5.43 ratio is...PEMCSFS54331- SKU:
- PEMCSFS54331
- Availability:
- Ships Same Business Day
- Weight:
- 42.00 LBS
- MFG Part #:
- CSFS54331
$718.99 -
PEM 9in Gear Full Spool 5.29 Ratio New Center Section CSFS52931
PEM
$718.99A full spool eliminates differential action, delivering maximum traction and acceleration off the line—essential for drag racing, circle track, and high-grip motorsports where wheel spin costs you races. The PEM 9-inch spool with a 5.29 ratio provides...PEMCSFS52931- SKU:
- PEMCSFS52931
- Availability:
- Ships Same Business Day
- Weight:
- 41.00 LBS
- MFG Part #:
- CSFS52931
$718.99Qty in Cart: 0Quantity:Price:$718.99Subtotal: -
PEM 9in Gear Full Spool 5.14 Ratio New Center Section CSFS51431
PEM
$718.99A 5.14 gear ratio in a full spool delivers aggressive acceleration and consistent power delivery on the track or strip—ideal for dedicated drag racing setups where every tenth counts. The steel spool eliminates differential slip entirely, ensuring both...PEMCSFS51431- SKU:
- PEMCSFS51431
- Availability:
- Ships Same Business Day
- Weight:
- 42.00 LBS
- MFG Part #:
- CSFS51431
$718.99 -
PEM 9in Gear Full Spool 6.00 Ratio New Center Section CSFS60031
PEM
$718.99A full spool eliminates wheel slip during hard acceleration by locking both rear wheels together, delivering straight-line power to the pavement without torque-induced breakaway. If you're serious about drag racing, road course competition, or maximum...PEMCSFS60031- SKU:
- PEMCSFS60031
- Availability:
- Ships Same Business Day
- Weight:
- 40.00 LBS
$718.99
