I am sure you will receive many letters pointing out that the gearbox in the photos of my Lotus 25 is not a ZF but a Hewland. It will be seen that there were spiders on the output shaft to drive the rubber doughnuts.
I do, in fact, have a ZF 5DS10. But Lotus did use a Hewland gearbox on chassis R6 for four races during 1963.
It had taken me 15 years to find the right ZF, but because the car has been raced regularly for the past 18 years, it was too risky to use. Another problem is that it’s impossible to change individual ratios on the ZF. Team Lotus had three gearboxes with different crown-wheels and pinions for each car. This meant that the whole gearbox had to be changed if the gearing was incorrect. At Spa, the highest gearing was still not quick enough and the rear tyres had to be increased from 600 L 15 to 650 L 15.
I am, Yours etc, Cedric Selzer, London