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BGM PRO Superstrong - the original 
Extremely durable clutch, very easy to use - Made in Germany

The Superstrong clutch combines extreme durability, absolute reliability and easy operation.
It is the basis of every solid engine tuning.
The solid, CNC manufactured clutch basket has an excellent concentricity as well as an enormously high torsional stiffness. It thus offers perfect clutch operation with a clearly defined grinding point and clean cutting. It can be used by touring riders who value high quality, as well as ambitious racers who are looking for an extremely resilient and stable clutch.

The clutch delivered ready for installation is adjusted for a power range up to approx. 20PS / 22Nm by means of the mounted clutch springs. Reinforced springs (sold separately, BGM PRO XXL) extend the power range of the clutch to over 40 HP. The bgm PRO Superstrong replaces any conventional clutch type used in the 
Vespa large frame models with inlet rotary slide control from around 1956 onwards.
Usable in Vespa VNA, VNB, VBA, VBB, T4, GL, Super, Sprint, Sprint Veloce, GT, GTR, TS, Rally, PX, Cosa and T5.

Vehicles with less than 180ccm (ex works) need the clutch cover of the 200ccm models, if the original existing clutch cover should not be modified. 
Vehicles built before 1998 have to be modified minimally to mount the Superstrong clutch (see documents under Downloads).

In the CR version, we offer the clutch with the lining type of the Honda CR80/VFR400.
These have a larger effective radius, less weight, wider lugs and a very resilient lining material. The advantages are a lighter clutch that separates faster and yet is extremely resilient.

Clutches with straight sprockets can only be combined with the corresponding straight primary gear. The engine must be completely opened for this purpose. The extra long primary reduction ratios based on the 62/63 tooth primary gear are only available with straight teeth. The high torque of the engines, which require such a long reduction ratio, is transmitted directly into the gear via a straight toothing, without exerting any lateral forces on the bearing of the auxiliary shaft. Thanks to precise manufacturing, the straight-toothed drives are as quiet as the helical drives.

A primary drive consists of a clutch (sprocket) and a primary gear.
Piaggio has already combined 65, 67 and 68 teeth of primary gears with different clutch sprockets ex works.
This makes it easy to adjust the overall gear ratio to the engine power.
A distinction is made here between 67/68 and 65 teeth.
Due to the different so-called gear module, the following gear/sprocket combinations can be used. 
Please note: BGM is the only manufacturer to offer different 22Z sprockets for 67/68Z and 65Z primary gears. This is the only way to ensure maximum stability.



< < PX200


primary wheel

primary wheel original installed in

Useable BGM Superstrong clutchs



23Z*, 24Z*, 25Z* (straight)




24Z*, 24Z*, 25Z* (straight)





22Z*, 23Z, 24Z*


All 125-180cc models up to and including year of manufacture. 1977

20Z , 21Z , 22Z, 23Z*


All 80-150cc models from year of manufacture 1978, all Cosa

20Z , 21Z , 22Z, 23Z*

*BGM sprockets with special module!


  • Longer gear ratio:
    • PX80/PX125 Drivers use a clutch with 22 or 23 teeth for gear ratio extension (suitable for primary 67/68)
    • PX200/Rally200 Drivers use a clutch with 24 teeth for gear ratio extension (suitable for primary 64/65).
  • Shorter gear ratio:
    • PX200/Rally200 Drivers use a clutch with 22 teeth to shorten the gear ratio (suitable for primary wheel 64/65).
  • TIPP
    Simply install the special BGM 64 teeth primary wheel for the largest possible gear ratio range (engine must be opened completely). Then by simply changing the clutch sprocket the engine can be reduced to fit a tame cylinder up to a torque steamer.
    Engines with a lot of torque and early power peak choose the straight geared clutches which also require a straight toothed primary gear (also available as a set). This allows very long reduction ratios to be achieved. Ideal even if the overall gear ratio is too short (e.g. MHR) for very sporty engines with modified auxiliary shafts and shorter gear steps. Also an option if the actual gearbox is very short (PX80) or the transmission ratio is too low due to a small wheel diameter (PX200 engine with 8 inch tires in Oldie).
  • DELIVERY Scope
    The scope of supply includes the complete ready-to-install clutch with bgm PRO Cosa clutch platesand ten BGM PRO XL springs. A new O-ring for the clutch cover, the woodruff key and a new clutch nut are also included. We use a nut with clamping part (MBN13023, T2, strength class 10, DBL9440.40) because we have gained the best experience with this also in racing operation with over 40PS shaft power. Tightening torque 70-75NM. We advise against other safety devices such as Nordlock, corrugated spring washers (DIN137) or serrated washers (DIN6798).

We also recommend a low-alloy gear oil of classes API GL3/GL4 for high-performance engines in order to avoid slipping of the clutch even under extreme loads. This also applies to our BGM Superstrong/Superstrong CR clutches. The old engine oil specification SAE30 corresponds to the current gear oil specification SAE 85W/90.

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