The 1963 Lotus Mk 27 Formula Jr. race car was a revolutionary design that helped to kill off this class of race cars. Lotus carried over the suspension and basic dimensions from the Lotus Mk 22. The difference is in the chassis. Lotus designed a monocoque aluminum tub with steel bulk heads. The first cars had a fiberglass outer shell that proved to make the chassis flexible rather than ridged. This was quickly changed and the Lotus 27 was the car to have in the Formula Junior series.