that car was like that

Silvio Grassetti’s triumph over the Honda World Championship by Tom Phillis, Taveri and Redman proved that the Japanese manufacturers were not invincible

Massimo Falcioni

– Milano

60 years ago, on May 1, 1962, the new Benelli 250 4-cylinder with Silvio Grassetti won the pre-world race on Cesenatico’s international circuit, beating the world-class Hondas from Tom Phillis, Taveri, Redman and Morini from Provini and Tassinari. Two weeks earlier, on April 15, at the Shell Gold Cup in Imola, Phillis and Redman had crossed the finish line in the two half “on parade”, confirming what had happened in the previous World Championship season, with the bikes from the Golden Wing dominating the World Championship 250 (4-cylinder 4-stroke close to 45 hp and 14,000 rpm) and 125 (2-cylinder 4-stroke from 22 hp to 14,500 rpm).

dared to run

In Cesenatico, in a daring race with Grassetti’s initial fall due to a hard contact in the basket with Provini followed by a hunting show of Pesaro ace overtaking 24 riders in a row, Benelli’s victory split with his new multiple it. proved that Italian motorcycling had not lowered its glorious flags and that Japanese houses were not invincible. The media influence of this exploitation is extraordinary: Grassetti and Benelli are on everyone’s lips and go on the front pages of newspapers with reports and interviews on radio and television. For the 26-year-old Grassetti, it is the inauguration among the big names in international motorcycling, where the Pesaro champion will be among the main characters for over ten years, until 1974. For Casa del Leone, founded in 1911 and in racing since the early 1920s ‘s it is a strong push to improve its image and expand its market share in Italy and abroad. The challenge therefore reopens on both the competitive and commercial front and continues, amid illusions and disappointments, since the opening of the 1962 World Championships in the Spanish GP, the week after the exploitation in Cesenatico.

technical difficulties

Throughout the ’62 season, Grassetti and Benelli will be the protagonists, but due to technical issues and mishaps, they will not win. Ditto in 1963, with Grassetti (Benelli) number two in the “tricolor” 250 behind Provini (Morini) – and first in the 500 with the 4-cylinder MV Agusta – but out of the game in the quarter-liter world championships, causing repeated engine problems new race car. At the end of 1963 there will be a change of leadership with a view to 1964: Provini, who by no means missed the World Cup, goes from Morini to Benelli, and Grassetti leaves Pesaro to Bologna, where the young Giacomo Agostini will find himself as a teammate at Morini. The arrival of the champion from Piacenza will give Benelli the push to open a new side by revolutionizing its 250 4-cylinder.

it was like that

How was the “duemmezzo” triumphant from Cesenatico in 1962 and the “base” on the bike that won the world championship in 1969? Clearly, a very different Grand Prix from the former single-cylinder, glorious twin camera, derived from Dario Ambrosini’s “red” world champion in 1950 and brought to the track in 1959 by Grassetti: excellent bike, but arrived late and unable, on despite its 32. HP at 11,000 rpm and 210 km / h, to withstand the impact of the two-cylinder MV Agusta, the “mono” Morini twin camshafts, 2-stroke MZ with rotating discs and much less the latest arrivals, the 4 -cylindered Honda. The lines of the new 4-cylinder engine (already in the early 40’s Benelli had created an innovative 250 4-cylinder front-speed, with compressor, liquid-cooled, a motorcycle with excellent technology and extraordinary performance in tests, but put out first by the events of the war and then by the new rules) had been drawn up since 1958 by the young engineer Aulo Savelli on the recommendation of the great chief of the Pesaro firm Giovanni Benelli. The new engine, with dual-axle distribution controlled by a cascade of gears located in the center, had vertical cylinders and did not follow the pattern of other previous multi-split race cars such as the Gilera, Guzzi, MV Agusta or current, such as. as Honda. This is above all to compress the engine in length by including the dimensions of the bike and the inclination of the front fork. The first 250 multicylinder, seen up close, expressed a sense of power and really aroused fear. The roar produced by the four megaphones made by hand with a hammer from a flat plate, aroused fear and at the same time exalted for its melody.

cutting edge

A technical state-of-the-art motorcycle in the world. Reverse tradition, as already written, are the four cylinders (bore and stroke of 44 x 40.6 mm = 247.2 cc) vertical axes, air-cooled. Special castings of light alloy. The timing system with two overhead shafts, with two inclined valves per. cylinder and coil valve springs (the four-valve comes from ’67 with Renzo Pasolini), is controlled by a train of central gears, the primary transmission is entrusted to a pair of gears with the small one located on the crankshaft between the first and second left cylinder. Dry clutch, six-speed gearbox (then seven and also tests with eight-speed), power supply with four 20 mm Dell’Orto, battery ignition with four coils and four-switch, dry sump lubrication and fuel tank, separated oil. Other features: the coils located under the top beam of the frame, the oil tank under the saddle and above all the great use of “special” materials. The frame, at the beginning of the development of the single-camshaft, is in special tubes with a double lower cradle, integrated alloy brakes with front with four jaws (with Provini, Benelli becomes the first GP motorcycle with disc brakes in ’65) and double control lever, tires 2.50 x 18 “front and 2.75 x 18” rear. Dry weight, 122 kg. Declared power of this first engine: 36.5 HP at 13,000 rpm with aluminum screen, over 220 km / h. But – as Grassetti will say years later – the first engine used in the Cesenatico did not reach 35 HP and did not exceed 12,000 rpm, even though the bike ran over 220 Km / h.

the prototype

The prototype of the new multi-cylinder race car will be presented to the press in June 1960, but the bike will have a problematic pregnancy debut during the race at Imola with Grassetti only on April 15, 1962. For months, the close and expert team from the racing department has busy day and night: with engineer Savelli there is the technician Armaroli, the old engineers from Dario Ambrosini, Filippucci, Maroccini, Gabucci, the frame builder Ivo Mancini under the supervision of Giovanni Benelli, his brother “Mimo” and son of former master Tonino Benelli, Paolo. In fact, the entire factory is committed to the project because almost all parts are designed and built inside. It is clear that Silvio Grassetti belongs to the group and enters the racing department every day after daily training in the winding and risky “99” (Km) track on the roads open to traffic in the Pesaro-Urbino-Fano-Pesaro square. In any case, the big work pays off: at the end of the ’62 season, at the Monza GP of Nations, the engine already exceeds 40 HP at 14,000 rpm with the bike over 230 km / h.

lubrication

The multi-cylinder is rough but changes with great ease, and Grassetti will take it over 15,000 rpm in 1963, but often pays the consequences of breakage due to lubrication problems that will be solved definitively with the new bike, from the middle of ‘ 64 and up, up to the race cars after Provini, with the latest scream from the ’68 -’69 models: 16-valve engine with almost 60 HP at over 16,000 rpm, 7-speed gearbox (there was also an eight-speed gearbox ), speeds above 250 Kmh, accelerations from… 500 cc. Since 1962, the strong side of the 250 4-cylinder from Pesaro has been in acceleration and its weak point in lubrication. So paradoxically, the bike was more competitive and more solid on mixed circuits, while the initial feats on the fast ended with the smoke clouds from the four megaphones and the sad return to the garage. Months passed and many changes were made: the separate oil tank was placed under the crankcase; the ignition system passes from the end of the camshaft to the front of the crankshaft to make the control more direct and smooth; the inclination of the valves when very open is reduced from 90 ° to 65 °, which improves the fuel supply and the combustion in order to make it possible to reduce the progress of the ignition from 50 ° to 30 °; the crankshaft union system is modified; The distributor ignition has been replaced with a magnet to give a more powerful spark at high revs without compromising on the easy start. We work hard, there are improvements, but the substance does not change: the power is there, the speed is there, the grip is missing. Throughout the two-year period 1962-’63, Grassetti asked for profound changes to the frame (to reduce weight and make the bike more drivable), to the engine (to improve traction and for a softer torque), to the gearbox (to achieve better acceleration in low gear) without getting satisfaction. The reason? As he himself will say: “For Benellis, I was always” their “Silvio, who grew up in the factory since 1956 and a winning rider with Leoncino 125. So they listened to me, pampered me, said yes to my requests, but then the bike essentially remained the same as before “. It will therefore be from 1964, the former “black beast” of the Pesaro company, Provini, to change the music in the Viale Mameli racing department with new musicians. In any case, the triumphant May 1, 1962 in Cesenatico is still crucial to pressure Benelli to continue, developing his high-quality project and large investments.

the results

The results speak for themselves. From 1962 to 1969, the 250 “4” finish line crossed 150 times: 50 victories, including 10 world championships, dozens and dozens of podiums and record laps, symbolic victories at TT, Spa, Monza, Imola, Cesenatico, Nurburgring, Le Mans, Assen, Opatija etc. A world title (Carruthers), 5 Italian titles (2 Provini, 2 Pasolini, 1 Grassetti losing at least two more due to… mishaps), always on the podium. In the latest version, the engine delivered over 55 Hp (but some have seen 60 Hp!) At 17,000 rpm (but it pulled up to 20,000!), With the bike well over 250 Kmh. Not satisfied, at Benelli’s they secretly prepared the weapon that might have tamed the Japanese and would have changed the fate of the world of motorcycle sports: the 250 8-cylinder 4-stroke V-shape! The new rules will take care of it, and not only that, to cut the wings of the dreams of the glorious Casa del Leoncino. However, Benelli will raise the bar with the new 4-cylinder 350 and 500, especially with Pasolini, Saarinen, Hailwood. But that’s another story.



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