By the time the Series 3 was born in 1959, the Lotus transaxle had become more reliable thanks to the Duckworth redesign on its own dry sump lubrication system, but the young engineer pointed out the inherent limitation of the box in the amount of torque it can safely handle.
 So the Series 3 was offered with the Lotus 'Queer Box' transaxle for 1.5L FPF only, and BMC 4-speed or ZF 5-speed gearbox with a conventional differential for cars with a larger FPF.

The frame was reinforced in the areas that are deemed to be weak on Series 1 and 2, and the front suspension was upgraded from the previous configuration which had come directly from Lotus 11 Series 2.
By the time the Series 3 was born in 1959, the Lotus transaxle had become more reliable thanks to the Duckworth redesign on its own dry sump lubrication system, but the young engineer pointed out the inherent limitation of the box in the amount of torque it can safely handle.  So the Series 3 was offered with the Lotus 'Queer Box' transaxle for 1.5L FPF only, and BMC 4-speed or ZF 5-speed gearbox with a conventional differential for cars with a larger FPF.
The frame was reinforced in the areas that are deemed to be weak on Series 1 and 2, and the front suspension was upgraded from the previous configuration which had come directly from Lotus 11 Series 2.
Lotus 15