The Le Mans Test Weekend became a big deal from the 1960s. One I recall vividly was the 1971 edition, largely because of the speed of the extraordinary long-tailed Porsche 917Ls there. The previous year’s race had seen the original 917 Langhecks dazzlingly fast in a straight line but unstable in yaw when cornering. For the new year, 17-inch wide rear wheel rims and matching tyres had replaced the previous 15-inch size, which had been accepted to minimise straight-line drag. To half-cloak these wheels the rear bodywork was wider but front and rear fender heights were minimised. Partly to restrict pitch-change and partly to take advantage of the smooth Le Mans track surface, the 917Ls’ vertical wheel travel was halved and stiffer springs used.
Changes at the concave nose included a wider, lower oil cooler which, thanks to the stiffer springing and minimised suspension travel, was slung within the bodywork closer to the ground than before to restrict airflow beneath the car. Larger brake cooling inlets each side of the oil cooler dictated revised headlamp mounting. To encourage hot air extraction from the brakes and minimise drag the rear edge of each front-wheel well was rounded off.
On the Sunday of that Test Weekend, Jackie Oliver took the finely-tweaked 917L round the historic old circuit at an average speed of 155.63mph – the first 250km/h-plus lap of the Sarthe. Jackie’s official lap time of 3min 13.2sec was some 7sec faster than the time Gulf-JW recorded for him in a short-tail 917K. John Wyer specified two 917Ls for the 24-hour race that June. They weighed in at 1876 and 1855lbs, while the sister 917L run by the Martini team scaled just 1833lbs. One reason for the Gulf cars’ extra weight was the team’s use of separate oil hoses from rear-mounted engine to front-mounted oil cooler instead of the normal Porsche system of using the chassis tubes. The idea was to avoid a chassis crack losing the oil, but given the perfidy of things mechanical both blue-and-orange Langhecks broke their engines after failures of the new hoses, after the Rodriguez/Oliver car had led for hours. The Martini 917L also failed, its cooling fan breaking adrift early on.
The Gulf-JW records recall of the Siffert/Bell car – chassis 045 – “The left-hand wheel bearing failed at 103 laps, and the hub carrier, spring and shock absorber were changed in 1:10:19”. Ultimately the engine’s crankcase cracked after ‘Seppi’ had completed 129 laps and Derek 98 laps. This car’s maximum rpm in fifth gear was logged as 8400rpm, max speed 236mph. The sister Rodriguez/Oliver car – chassis 043 – ran to 8300rpm, 234mph. Its retirement was caused by a burst oil hose while, “The left-hand rear wheel bearing failed at 187 laps and the hub carrier and driveshaft assembly were changed in 17:59”. Pedro completed 198 laps in their 11¾-hours of racing, and Ollie 76 laps. Heroes all…