The Kyosho LA-32 parts bag contains the front axle box. The box consists of two halves: one front and one rear. The box will house the front differential.
The Lazer ZX manual states that a needle shaft and roller should be installed in the front differential box. Later versions omit this. The needle roller ensures the belt remains in contact with the front differential. I don’t know why it was deleted in the ZX-R but it probably added some drag and doesn’t really contribute to the belt staying put.
The front axle box is known for breaking following the front tower touching the ground and bending / breaking in a crash, in turn breaking the axle box. Alternative parts (2 halves) are provided through Shapeways which are stronger.
It is also recommended to install langer screws in the top of the gearbox. These are the mount screws for the front shock tower. Installing 14mm rather than 12mm screws will ensure their ends touch the top deck front screws, creating a solid connection that prevents the gearbox from bending and breaking backwards.
Installing a solid front tower with the two tops connected also prevents the tower to twist, preventing breakage through too much force on one side of the gearbox mounting points.
