Spindle in the kart

As everyone knows, spindle is that component of the steer kinematic chain that allows the mounting of the front wheels and also makes them steerable by means of the connection to the steering linkage. Spindle particular geometry, articulated in space according to two characteristic angles (A and  in Figure 1), is relevant for vehicle performances. This particular geometry influences steering kinematics, acting on the magnitude of wheel vertical displacement when the steering angle is varied, and then influencing the raise of the inner back wheel during cornering. Furthermore, spindle pin, on which the wheel is mounted, has its own bending flexibility, determined by spindle geometry and material. Then spindle acts on vehicle torsional behaviour, on load transfers and also changing camber angle: the more the spindle is flexible the more ha camber angle will change during cornering.
Concerning fabrication, spindle is made by three main components: pin, bushing and the plate used for the connection to the steering linkage.
Pin is obtained from a block of material by turning, that is also used for the realization of the thread that is used for nut clamping. The bushing too is realized by turning, while the plate is obtained by sheet metal punching (in the case the plate is plain) or by forging (if the plate has a complex shape like the one in figure). In some kinds of spindles there is no bushing, and that component is substituted by a sheet metal “C”. The main spindle components are finally welded together to form the assembly.


Ing. Fabio Renzi
TVK Project s.r.l.
Motorsport software and consulting
Via Ignazio Guidi, 44
00147, Roma

renzi@ing.uniroma2.it
fabio.renzi@tvk-project.com
www.tvk-project.com

Phone +39 0672597136