At this time however it became clear that the AMR 33 suspension system, that originally had been intended to be used on the AMR 35 also, was very unreliable: the suspension units were simply too weak to withstand the forces caused by driving cross-country. A complete redesign of the suspension was ordered, also to be used for the new Renault R35. Three types were considered and tested on AMR 33 prototype N° 79758; the first had the idler resting on the ground; the second two bogies and five road wheels, like the R 35. This Renault ZB was rejected, but in March 1936 twelve were ordered by China and four a few months later by the Yunnan province administration. The latter were delivered in October 1938, the former only in 1940. The third suspension type had only one bogie per side and was accepted. The Renault factory designation of the vehicle with the relocated engine and new suspension was Renault ZT; it merely indicates the chronological order of Renault's military prototypes and has no further meaning.