CLOSE RATIO COOPER S LAYSHAFT & 18 TOOTH 1st MOTION SHAFT [C-AJJ4032]

4Spd All Synchromesh Close Ratio Cooper “S” Gear Set

Upgrade your Classic Mini gearbox with this high-quality close ratio helical gear kit, designed to improve acceleration, gear spacing and overall driving performance while retaining smooth, quiet operation.

This kit converts a standard pre A+ 4 synchromesh gearbox to the highly desirable Cooper “S” close ratio setup. By reducing the gap between gears, it helps keep the engine in its power band during acceleration and gear changes, making the car feel sharper, more responsive and far more enjoyable to drive.

This kit contains

• 1 x Lay gear
• 1 x First motion shaft

In all 4-synchro remote gearboxes, the internal gearsets were largely identical except for the laygear and 1st motion shaft, which determined whether the gearbox was standard or close ratio.

Cooper S Close Ratio Specifications

• 22G1040 laygear
• Tooth count: 15, 20, 25, 29
• IMPORTANT: THIS LAYGEAR MUST BE USED IN CONJUNCTION WITH A 18 TOOTH 1st MOTION GEAR A STANDARD ALL SYNCRO MINI G/BOX HAS A 17 TOOTH 1st MOTION GEAR.
• Closer ratio gearing compared to standard boxes
• Improved acceleration and sportier driving characteristics

Important Identification Information

Identification of a genuine close ratio gearbox is done by inspecting the laygear itself. If the gearbox contains a 22G1040 laygear, it is a close ratio transmission.

Please note:

• The 25 tooth gear on the Cooper S laygear measures approximately 3” diameter
• The 25 tooth gear on a standard gearbox is slightly larger in diameter than 3″
• Care should be taken when identifying and sourcing replacement components

Additional Information

These close ratio gearsets have also been fitted into later rod-change gearboxes where owners wanted improved gear spacing, however layshaft modifications are required for those conversions.

Suits

• Classic Mini
• Mini Moke
• 4Spd all synchromesh gearboxes
• Does not suit rod-change
• 1 Required per vehicle

Benefits Over Standard Wide-Ratio Gearing

• Faster acceleration
• Improved gear spacing
• Reduced RPM drop between shifts
• Better throttle response
• Sportier driving feel
• Ideal for modified engines

This setup is especially useful for tuned Minis, where keeping the engine pulling strongly through the rev range can make a noticeable difference to performance and drivability.A fantastic upgrade for anyone building a fast road, rally, hill climb or performance Classic Mini gearbox.