Edo Vigna has been in the motorsport world for over 50 years, first as a motocross rider and then as a technician, starting with the preparation of motorcycles for uphill races. His curriculum also includes a decade as a teacher of mechanics in a vocational training center. On leaving this job, he dedicated himself to his passion for motorcycles full time, achieving the first important milestone with a victory in the Sport Production Championship in 1992 with the Ducati 888.
In 1995 he was the technical and engine in-charge person for the Taurus Team in the SBK World Championship, finishing in seventh place and the best private team (a result which has still not be surpassed) with the late Fabrizio Pirovano. In 1996 he worked with the Promotor Team, winner of the SBK World Championship with Troy Corser. In 1997/1998 he was technical manager of Suzuki in the World Championship on its debut in the SS 600 class with the GSXR. Many other results followed over the years in various categories such as victory in the Italian Superstock Championship and third place in the European Championship in 2007 with the MV F4R and rider Luca Scassa.
From the experience matured, he understood that the poorly split Ducati engines suffered many breakages due to over-revs under braking. On this observation, he began developing a system that would prevent these problems. Over the course of at least 25 years he evolved this type of clutch for motorcycles with increasing results, first in collaboration with STM, then on his own. Progress acknowledged by manufacturers such as Ducati Corse, which used EVR slipper clutches in the SBK World Championship for 4 years, or double victory in the 2020/2021 World Championship in the SS300 category with Kawasaki, and many other successes in the Italian championships as well. On motorcycles, the slipper clutch reduces the effect of engine braking by releasing the rear wheel during the release phase according to a "law of release" deliberated during the set-up or tuning phase. In addition to safeguarding the engine, this type of clutch prevents the rear wheel from hopping and allows for a smoother, more fluid ride, especially when braking, entering and taking curves, cornering, ensuring an advantage that no rider or two-wheel technician could ever renounce today.
EVR slipper clutch and karting
While attending a karting race, Edo realized that the slipper clutch could also have an advantageous use in this type of competition. After 2 years of tests and developments, also thanks to the availability of Luca Raineri, both a fast and sensitive test driver, the slipper clutch for the TM 125 KZ R1 engine came to light. The fine tuning allowed EVR to maintain the advantages of the light engine-brake when braking of these small 2-stroke 125 engines, but also reducing the instability of the rear axle and thus improving the adherence of the wheels to the ground in this delicate phase, as well as ensuring greater smoothness often difficult to achieve. During tests and races, this feature also allowed to reduce the problems of setting up the chassis, solving any potential problems. The action of the EVR clutch can be easily customized according to the driver’s needs. Among the other advantages that emerged is the reduction of over-speed in downshifting, which ensures greater durability of the various transmission components (gearbox, clutch bell, first of all) and crankshafts. In addition, in case of seizure, the wheels are not blocked, thus preventing dangerous crashes. Used by Raineri and many other drivers, this clutch already obtained numerous victories, five out of five, highlighting the advantages in driver sensations, and not least a longer duration of the tires that denote more regular wear, not being also subjected to blockages. To comply with the technical regulations, the project was submitted to the CIK technical commission in the person of the technical coordinator Karl Janda, who gave a favorable opinion on its use, also in consideration of the greater safety in case of seizure.
Explanation on the functioning of the EVR slipper clutch for karts
During acceleration, the EVR slipper clutch behaves like a normal clutch, discharging engine torque to the wheels. By rapidly reducing the ratios near the entrance to a curve, there is a phase in which the driving wheels tend to push the engine over the red line, or trigger an annoying vibration of the rear axle. During this time, the EVR slipper clutch, thanks to its mechanism, intervenes with slight slippage to equalize the speed of the wheels with the engine rpm. At the end of this phase, the clutch returns to its normal functions. This intervention can be configured according to the driver's driving style and feeling. The clutch can be mounted on the original engine without making any changes and using its disc pack. There is no abnormal wear of the clutch discs and the duration of the assembly is equal to the original. The only little noticeable effect is a slight slippage during the engine start-up phase of the kart, a sign the clutch is working optimally. As required by the Federation, the clutch's external appearance is similar to the original. These clutches were also designed for Iame, Vortex and Modena Engines. The EVR slipper clutch is obviously patented and for those who make copies, it is good to know that improvements are already underway that will enhance its functionality.
In 1995 he was the technical and engine in-charge person for the Taurus Team in the SBK World Championship, finishing in seventh place and the best private team (a result which has still not be surpassed) with the late Fabrizio Pirovano. In 1996 he worked with the Promotor Team, winner of the SBK World Championship with Troy Corser. In 1997/1998 he was technical manager of Suzuki in the World Championship on its debut in the SS 600 class with the GSXR. Many other results followed over the years in various categories such as victory in the Italian Superstock Championship and third place in the European Championship in 2007 with the MV F4R and rider Luca Scassa.
From the experience matured, he understood that the poorly split Ducati engines suffered many breakages due to over-revs under braking. On this observation, he began developing a system that would prevent these problems. Over the course of at least 25 years he evolved this type of clutch for motorcycles with increasing results, first in collaboration with STM, then on his own. Progress acknowledged by manufacturers such as Ducati Corse, which used EVR slipper clutches in the SBK World Championship for 4 years, or double victory in the 2020/2021 World Championship in the SS300 category with Kawasaki, and many other successes in the Italian championships as well. On motorcycles, the slipper clutch reduces the effect of engine braking by releasing the rear wheel during the release phase according to a "law of release" deliberated during the set-up or tuning phase. In addition to safeguarding the engine, this type of clutch prevents the rear wheel from hopping and allows for a smoother, more fluid ride, especially when braking, entering and taking curves, cornering, ensuring an advantage that no rider or two-wheel technician could ever renounce today.
EVR slipper clutch and karting
While attending a karting race, Edo realized that the slipper clutch could also have an advantageous use in this type of competition. After 2 years of tests and developments, also thanks to the availability of Luca Raineri, both a fast and sensitive test driver, the slipper clutch for the TM 125 KZ R1 engine came to light. The fine tuning allowed EVR to maintain the advantages of the light engine-brake when braking of these small 2-stroke 125 engines, but also reducing the instability of the rear axle and thus improving the adherence of the wheels to the ground in this delicate phase, as well as ensuring greater smoothness often difficult to achieve. During tests and races, this feature also allowed to reduce the problems of setting up the chassis, solving any potential problems. The action of the EVR clutch can be easily customized according to the driver’s needs. Among the other advantages that emerged is the reduction of over-speed in downshifting, which ensures greater durability of the various transmission components (gearbox, clutch bell, first of all) and crankshafts. In addition, in case of seizure, the wheels are not blocked, thus preventing dangerous crashes. Used by Raineri and many other drivers, this clutch already obtained numerous victories, five out of five, highlighting the advantages in driver sensations, and not least a longer duration of the tires that denote more regular wear, not being also subjected to blockages. To comply with the technical regulations, the project was submitted to the CIK technical commission in the person of the technical coordinator Karl Janda, who gave a favorable opinion on its use, also in consideration of the greater safety in case of seizure.
Explanation on the functioning of the EVR slipper clutch for karts
During acceleration, the EVR slipper clutch behaves like a normal clutch, discharging engine torque to the wheels. By rapidly reducing the ratios near the entrance to a curve, there is a phase in which the driving wheels tend to push the engine over the red line, or trigger an annoying vibration of the rear axle. During this time, the EVR slipper clutch, thanks to its mechanism, intervenes with slight slippage to equalize the speed of the wheels with the engine rpm. At the end of this phase, the clutch returns to its normal functions. This intervention can be configured according to the driver's driving style and feeling. The clutch can be mounted on the original engine without making any changes and using its disc pack. There is no abnormal wear of the clutch discs and the duration of the assembly is equal to the original. The only little noticeable effect is a slight slippage during the engine start-up phase of the kart, a sign the clutch is working optimally. As required by the Federation, the clutch's external appearance is similar to the original. These clutches were also designed for Iame, Vortex and Modena Engines. The EVR slipper clutch is obviously patented and for those who make copies, it is good to know that improvements are already underway that will enhance its functionality.
