The Clutch’s Design

Reversing the Clutch’s operating principle required significant engineering effort. BFA manufactured a custom primary Drive Sprocket specifically for this Clutch. This not only creates a sturdy and durable solution, but the Drive Sprocket’s flat design also frees up a significant amount of installation space. This is a crucial prerequisite for accommodating 5 friction plates within the Clutch.

The Clutch Pinion is connected to the CNC-milled outer aluminum cage via 12 Screws. A Needle Bearing is located between the inner and outer cages in place of the original bronze bushing. The Clutch is actuated via a ball-bearing-mounted Pressure Plate.

All friction plates and Cover Plates in the Clutch assembly are made of aluminum. The bottom plate houses 6 Springs—similar to those in a Vespa Smallframe Clutch—which can be supplemented by 6 small Springs in the center.

The package includes a spur-toothed primary drive. It also includes two Screws used to compress the Clutch. This allows the friction plates to be replaced while the Clutch is installed. The set also includes two rings that can be used to space the Pressure Plate at the correct height relative to the Clutch Cover.

The entire assembly fits under the original PX200 Clutch Cover. Occasionally, some minor adjustments are necessary. Parts from the Vespa Smallframe Models are used as friction plates.

The 2.0 Version

The 2.0 version is a minor update to the SIP-BFA Clutch. Tolerances have been reduced, wall thicknesses increased, and the outer cage now features a surface finish.

The SIP-BFA Clutch is available in various versions

• Compatible with the original clutch mounting on PX crankshafts
• With teeth that form a virtually indestructible connection with the Crankshaft. However, this requires a Crankshaft with the same tooth profile
• Both variants are available with Z 22, Z 23, or Z 24 Clutch Gear Cogs

Conclusion: The BFA Clutch for Vespa Largeframe models is an absolute high-end solution for smooth, reliable, and easy-to-operate power transmission between the engine and transmission.

Technical Details

• CNC-milled outer aluminum cage, fitted to the primary pinion in 12 places
• CNC-machined inner steel cage with anti-rotation feature for the Cluster Circlip
• Needle Bearing between the inner and outer cages
• 5 friction plates from the Vespa Smallframe Clutch
• Bearing-mounted Pressure Plate
• CNC-milled aluminum Cover Plates on top and bottom
• 12 Springs, 6 on the inside and 6 on the outside
• Includes straight-toothed primary gear 22/64, 23/64, or 24/64
• Clutch Friction Plates can be replaced while the assembly is installed
• Can be installed with the original PX200 Clutch Cover

These products fit perfectly – SIP TIPS:

• The crankshaft of the BFA casing with a 64 mm stroke is equipped with the gear teeth
• For precise control, we recommend the SIP PERFORMANCE clutch cable
• BFA recommends 10W-30 oil
• The CRIMAZ “Rallino” further facilitates Clutch operation

Feedback from the scene

“The Clutch works absolutely perfectly. When engaged, you no longer feel any reaction at all on the rear wheel. It engages very smoothly and transmits even very high forces without any problems.”

–Jesco, SIP Team, Tacho-Karacho Race 2018

Note: The Clutch Basket and Drive Sprocket are delivered pre-assembled. This means that the 12 Screws connecting the two parts are not yet fully tightened or secured. Please tighten the Screws securely and lock them in place with Thread Locker before putting the unit into service.