I believe he had been ill with kidney problems for some time and required dialysis. Very fond memories of watching him race between 1960 and 1967 at Longford in Tasmania, which was at the time, the fastest race track in the southern hemisphere. From Coopers to his own Brabham cars.
One particular race stands out which was the 1965 Australian Grand Prix. Brabham was leading when he was touched while lapping a slower car under brakes into Mountford corner, causing him to spin. He drove into the pits for a quick suspension check and then blasted out, by now well down the field. He didn't win but finished second by 1/10th of a second to Bruce McLaren but what a drive.
He wasn't called "Black Jack" for nothing and it wasn't unusual for his cars to have the latest and best fittings while his customers would have to wait for theirs. He also perfected the move, if not inventing it, of "shutting the gate" on anyone trying to overtake under brakes. Never the less, a gentleman and along with Stirling Moss, one of the last to have raced in the era of gentlemen during the 1950s'.