W.O. Bentley changed his mind about Le Mans and wholly supported Capt. Duff who again shared his 3-litre — this time with four wheel brakes — with factory test driver Frank Clement.
The ACO made a few changes of their own. The best was to move the race date three weeks nearer the summer solstice. The vile weather of the inaugural Vingt Quatre Heuers de Mans was fresh in their minds when they revamped the rules and scheduled the race for the 14-15 June, 1924.
Le Mans organisers remained serious about promoting and enhancing touring car utility and practicality by requiring a minimum of 20 laps between refueling and the introduction of coolant and/or lubricants. And another new rule: After the opening five laps a mandated stop to raise the hood which had to remain in place for two consecutive laps despite the extraordinarily fine mid June weather.
On the fifth lap John Duff got a polite ovation for a record 41-second pit stop to comply with the new hood rule. Alas, a lap later he tore past the pits at over 60 mph driving with one hand grasping the top with the other. Lagache, winner of the inaugural Le Mans in 1923, was flagged to a halt when he missed the five-lap top deployment window as required by the rules. Braking hard Lagasche slid to a stop, reversing against race direction, nearly 100 yards back to the pits, where he commenced the laborious job of erecting the fiendishly complex and tent-like hood on the number three Chenard-Walcker straight-eight.
Nonetheless Lagache led at 7:00 PM from a further quartet of French cars and Captain John Duff, still in the cockpit of the lone Bentley.
Dusk begins Le Mans unofficial social hour and the restaurants began to fill. The jazz band that was such a hit the year earlier, tuned up just as spectators in the pits spotted a tower of smoke out on the circuit.
The plume, rising from Tertre Rouge, signaled the end of the of Leonard/Lagache Chenard-Walcker the latest to swell the steadily growing DNF column. Two of the smaller entries had retired on the first lap. The fine French summer weather summoned a much faster pace than the soggy spring date a year earlier.
The competitors were learning Le Mans’ unwritten rules of speed and pace. By 10:00 p.m. just 24 of the original 43 starters were running.
The lone Bentley nearly joined the ranks of the retired when Duff took over from his diminutive teammate at 11:30 p.m. A balky starter required a firm human touch and the popular Capt. Duff was finally away when his engine sputtered unexpectedly: Frantic pumping revived the Bentley’s flagging fuel pressure and the green number eight resumed its pursuit of the larger, more powerful leading Lorraine.
At one point Duff was reclaiming over 18 seconds a lap. During the middle of the night the Bentley’s charge was blunted by a pair of broken rear shock absorbers.
Duff, London’s sole Bentley agent, had chosen Duralumin shocks absorbers over the standard steel dampers. By half distance he regretted the choice but didn’t slacken his pace or pursuit.
The fatal blow for the big French cars came just before 9:00 A.M. Duff spent the morning cleaving up to ten seconds each lap from the leader’s margin and moved into first place when Block’s leading Lorraine-Dietrich was halted by a tire failure.
On the 107th lap Duff put the big French car a lap down during the race’s crystal moment. Just after lunch with two and a half hours remaining with tires much on his mind Duff pitted for a precautionary tire change. It was an agonizingly long stop: Le Mans rules require that all work be done by the driver.
The perspiring Duff struggled with a seized wheel locking ring. The protracted wheel changing episode had demoted the Bentley from the lead and despite record retirements Duff was uncertain of victory until the bombardment of bouquets upon his arrival in the pits just after 4:00 o’clock.
The margin of victory was a single lap. Duff’s diligent pre-race preparations included the obvious addition of front wheel brakes plus armour for the fuel tank and proper and functional wings.
That solved the problems that 13 months earlier cost the brave little dealer team from St. Martin’s Lane victory in the first 24 Hours. The 24 Hours of Le Mans had developed, in just two years, its own grammar, protocols, traditions and rituals of preparation.
Having W.O. Bentley himself as chef d’equipe had certain positive effects on Duff and Clement’s French country weekend away.