Take suspension loads out of the arms, rods and bellcranks and into the frame tubes.
Welded steel tabs at every pickup point, sized for bearing stress at the bolt hole and for bending. Tab position accuracy directly sets kinematics, which is why the finished frame is measured with a FARO arm and the deviations are pushed back into the models.
No part-specific design process is documented. The Frame subsystem design process applies: 1. Kinematics supplies the pickup points and an LLTD range; the intersection of the frame-stiffness curve with that range sets the torsional stiffness target (CR26E: 1651 lb-ft/deg design target, from an LLTD target of 41.6% within a 39.5-42.5% range). 2. Model in SolidWorks 1D beam element FEA: couple moment across the front axle, rear upright points fixed, actuation geometry as trusses, representative engine tubes, displacement measured at the front upper pickup points. 0.5 in mesh spacing after a convergence study. 3. Physically test on the torsional stiffness jig: solid dampers installed, rear spindles fixed, front spindles on a pivot beam, weights hung at known distance. Historical FEA error 2.94% (CR22), 10.23% (CR25), 19.60% (CR26E). 4. Analyse each suspension tab for bearing stress and bending at its critical load case. 5. Weld in CNC-milled 6061 jigs with dowel pins; heat treat suspension nodes; FARO the finished frame.
Load cases are re-evaluated each year. CR26I front: upper fore -33.750 lbf delta (cornering critical), upper aft -49.410 (cornering), lower fore -116.767 (braking), lower aft -96.009 (braking), spring chassis +14.902 (cornering), pivot axis center +11.591 (cornering), tie rod chassis -22.451 (braking). Rear: upper fore -31.839, upper aft +8.000, lower fore -100.431, lower aft -150.371, spring chassis -22.480, pivot axis center -13.093, tie rod chassis -21.607. FEA setup for the front lower fore tab under maximum braking: roller/slider on the outside faces of the pin, bearing load applied on the pin, fixed at the frame tube contact faces, contact interaction between pin and tab.
Waterjet or laser cut, then TIG welded to the frame in the welding jigs.
4130 steel sheet, TIG welded to the frame tubes.
Manufacturing variability. Several CR26I suspension points measurably deviated from nominal: front left upper arm tabs, front bellcrank tabs, rear bellcrank tabs and rear upper arm tabs. The process now includes FARO measurement and model adjustment rather than assuming nominal.
Nothing in CrimsonStorage covers these yet.