Transmits steering torque from the wheel to the rack.
A two-piece column: a column-to-spline shaft carrying the quick release, and a rack-to-column shaft. The two are joined through a universal joint so the wheel angle can be set independently of the rack angle. The column runs in a bearing housing mounted to the frame. Design Philosophies and Processes: Inherited from the Steering subsystem design process: 1. Kinematics sets steering geometry, Ackermann targets and rack travel. 2. Size the column and shafts for torsional stiffness and for the bearing housing that supports them. 3. Calculate static steering force from the tire and geometry, and check it against anthropometric limits. 4. Design the wheel shell around the button and switch layout and the dash sightline; prototype grips and take driver feedback. 5. Validate steering effort and Ackermann on track, using the alternate tie rod mounts to sweep setups.
Cockpit template and the driver's legs bound the column path. CR26I steering angle is 18.60 deg against an ergonomic optimum of 2.93 deg, a deviation forced by design limitations and subsequently tested and found functional. From the design reports and one-pagers: From the CR25 Steering System Design Report: the two U-joints in the column must have the same angle; the apex joints must be in phase; and the angle of the joints cannot exceed the maximum working angle of the joints. Those three constraints are exactly what CR22 violated, and the Fault Vault entries follow directly from them. Rules: V.3.2.3 the steering system must use a rigid mechanical linkage capable of tension and compression loads. V.3.2.5 allowable steering system free play is limited to seven degrees total measured at the steering wheel. V.3.2.6 the rack must be mechanically attached to the chassis. V.3.2.7 joints between all components attaching the wheel to the rack must be mechanical and visible at technical inspection; bonded joints without a mechanical backup are not permitted. V.3.2.8 fasteners in the steering system are Critical Fasteners.
Column tubes are lathed and parted to size. The holes in the apex joints are drilled and reamed in the mill across two setups; the probe point must be on the same side for both, because what matters is the distance between the holes. Assembly: the rack and column must go in at the same time. Loosely fasten the rack to the rack mounts, fasten the top of the column to the car, and only then torque the rack mounts.
Steel shaft. From the design reports and one-pagers: Apex joints were selected because they are sealed and greased, which helps consistency.
Four separate Fault Vault entries, which together make the steering column the most fault-logged part on the car. 2023-07-13, CR22, Manufacturing, Compromised Failure. Steering did not lock evenly on both sides because the apex joints were not phased properly. Holes were added at a 90 degree offset and the joint orientation was flipped. 2023-07-17, CR22, Design, Complete Failure. Strong friction in the centre and near lock. Switching to the Mark Williams geometry increased the operating angle by 2 degrees, putting the joints over their maximum operating angle. Putting the apex joints deliberately out of phase was tried and did not work. Recorded conclusion: requires redesign. 2025-05-16, CR25, Operational Errors, Performance Failure. A saddle washer snapped from overtorquing a bolt, which led to increased play in the steering system through oversized holes in the column. Corrective action: do not overtorque, and properly align and size the holes. CR25, Manufacturing, Potential Failure. Slightly oversized and off-centre bolt holes in the column allowed extra rotational play. Corrective action: drill all holes on the CNC mill. CR25, Design, Potential Failure. The connection of the column to the steering rack did not account for proper clearance between the OD of the rack output shaft and the ID of the column, so the fit was loose enough to let the column wiggle left and right and slide fore and aft. 3D printed spacers and sleeves were added trackside to varying effect. The recorded fix is a thicker bottom column tube with the ID lathed to fit the rack properly; CR26E additionally added a centre column support bearing.
CR26E added a centre column support bearing. The recorded fixes still open from CR25 and CR26I are a thicker bottom column tube with the ID lathed to fit the rack, drilling all column holes on the CNC mill rather than by hand, and a jig for aligning the wheel to the spline when drilling the last set of holes.
Nothing in CrimsonStorage covers these yet.