With the Spanish GP opening the season for Formula One Championship races in Europe there was a lot of pre-race testing going on at the little Jarama circuit and some of it was useful for the race itself and some was purely experimental. Since Porsche revealed last year that they had been racing cars with solid rear axles, that is with no differential unit, relying on the distortion in the tyres to provide any required differential while cornering, the Formula One scene has been looking towards Stuttgart and wondering. Already McLaren have tried the idea and at Jarama both Ferrari and Lotus did some testing with a transmission devoid of differential. Ferrari found there was too much tendency for the rear end to push the front end off the road on corners, but Lotus were very satisfied and retained theirs for the race. All Formula One cars use limited-slip differentials, mostly of Hewland design, in which something like 15% of slip is allowed before the differential locks-up automatically and provides a solid axle. Various experiments have been tried with different percentages and now the zero % axle has been proven for certain circumstances. Its main advantage is instant traction on acceleration, but the disadvantages are the stresses and strains when cornering or sliding the rear wheels out of line, so that the best results are obtained by smooth, constant radius cornering.
During the pre-race testing one team tried Cosworth DFV engines prepared by four different specialists, and those prepared by Cosworth themselves and Nicholson-McLaren Engines Ltd. proved to be the best (and it was not the McLaren team that were doing the testing!). The Colnebrook firm were much too busy testing a new McLaren M26, number 2 in the series, and deciding to concentrate on this new car with James Hunt, rather than fog the issue by alternating between it and an old M23; leaving Jochen Mass to run M23/12 until such time as they have proved the M26 and built another one. With the first M26 scrapped after testing (and crashing) in South Africa, M26/2 was built with numerous modifications, including the cockpit controlled rear anti-roll bar, worked on the same principle as used by Lotus last year, in which one of the operating arms is in the form of a blade that can be rotated to give maximum stiffness or zero stiffness by reason of its bending moment, thus imparting this to the anti-roll bar Or tube itself. In the McLaren system there is a movable blade at each end of the roll-bar, interconnected by links and rods, so that they can get twice the effectiveness for the same movement of the cockpit control. Anti-roll bars are a complicated subject, apparently not understood by everyone, for one of the important factors is that the mountings should be rigid, yet you see anti-roll bars attached to mountings that seem to have little support from the main structure of the car.
There were five brand new cars in the paddock for the race, the McLaren M26/2, a new six-wheeled Tyrrell, a new DN8 Shadow, a new Hesketh and a new March, while the six-wheeled March 240 was on display by Rothmans International in a hotel in Madrid, and it certainly attracted a tot of attention even if there was no explanation of why it was there. The new Tyrrell was P34/7, for Depailler, and was to 1976 spectfication, with narrow track, short wheelbase and old-style bodywork with windows in the Cockpit sides. It was a rather expensive sign of despair in the Tyrrell Team, for they were trying to find out why the sleek 1977 cars are not competitive, by making a direct comparison with the original layout that looked so promising last year. Peterson was driving the smooth 1977 car P34/5, and the team also had P34/6 as a spare and P34/2 which had been used for experimental work. Both team cars had a cockpit control to alter the brake balance front to rear, by a cable that wound the brake pedal balance-bar along its thread. While useful, this device was not ideal, for the drivers found they would also like to alter the balance between the pairs of front wheels.
The Shadow team had a new DN8 model, number DN8/4A, with much smoother bodywork and an engine cover with air ducts built into the cockpit sides in place of the “ears” on each side of the crash-bar. The team drivers relied on the earlier cars for the race, Alan Jones with DN8/3A and Renzo Zorzi with DN8/1A, though Jones tried the new car briefly during the unntimed practice session. Although Lord flesketh closed down his racing team at the end of 1975, with public displays of tears falling into his champagne, activity at the stately home did not stop completely and last year Team Manager Horsley operated a Rent-a-Drive scheme with the 1975 cars uprated to D-series 1976 Cars. At the Race of Champions at Brands Hatch a brand-new Hesketh appeared in the shape of the 308E, from the drawing board of Frank Dernie, with financial support from various advertisers, including the driver’s father, Mike Keegan of British Air Ferries. Rupert Keegan was driving 308E/1 in his first Grand Prix, and a second 1977 Hesketh 308E/2 was completed for Harald Ertl and his various sponsors, while a third car is nearly completed, so the Hesketh Motor Company are clearly back in business. The final brand-new car was a March 761 from the irrepressible Frank Williams, who seems to be able to produce a car from bits and pieces at the slightest flutter of sponsorship money. The reconstruction of the Walter Wolf team saw Williams out on his own -again, and out of his small factory in Reading, but he soon re-established himself in new premises and with money from various deals and from the Belgian driver Patrick Neve, he conjured up a March 761, Although the major components came from the Bicester firm they did not build the complete car and Williams incorporated numerous items of his own. As Brian Henton had built a March 761 on similar principles, which was numbered 761/7, we could only call the Williams March 761/7A.
The rest of the cars were old friends from South Africa, Long Beach, South America and the Race of Champions, as can be seen from the table of practice times. Altogether there were 43 cars in the paddock, though many of them were not used, in fact Team Surtees were the only ones to use a spare car during timed practice, though Shadow, Tyrrell and others ran their spare cars during the untimed session on Saturday morning. Now that Hewland have at last completed production of a 6-speed version of their traditional transmission unit, many teams had them, but few used them, and teams like McLaren and Brabham who had built their own already wondered what all the excitement was about. Similarly the much heralded Cosworth DFV magnesium engine found its way into the paddock at last, but only with magnesium cylinder heads, which save a mere 19 lbs. in weight. Admittedly it is weight that is above the centre-of-gravity of the car, which must help rather than hinder the handling, but is unlikely to affect the performance. Ironically, one March driver was seen with a 42 lbs. lump of lead bolted to the front of the chassis to try and improve the front end adhesion!
The German ATS team had the latest pair of Penske cars, PC4/01 and PC4/02 for Jarier to drive, Emilio de Villota, the local Spanish driver had the ex-works McLaren M23/6, with “standard” Cosworth engine and 5-speed Hewland gearbox, Arturo Merzario had the ex-works March 761B/2 driven earlier by Ribiero and the BRM was driven by the Swede Connie Anderson, replacing Larry Perkins who had opted out of the “World Beater from Bourne”. D.S.J.