Crimson Racing Wiki

Torsion Bar Ends

Subteam: SuspensionSubsystem: ARBAssembly: Front ARB Torsion BarCars: CR21

Purpose

Terminate the CR21 torsion bar and connect it to the actuating arms.

Design Process

No part-specific design process is documented. The ARB subsystem design process applies: 1. Take the roll rate targets and the LLTD range from vehicle dynamics. 2. Size the torsion bar. CR26I: AISI 4130, 0.5 in OD, 0.33 in ID, 68.12 lb-in/deg torsional stiffness, contributing 1160 lb-in/deg (96.7 lb-ft/deg) to roll rate at nominal. 3. Design the blade and set the drop link positions. Five settings give blade lengths from 4.43 in to 5.57 in and roll rate contributions from 113.8 down to 72 lb-ft/deg. 4. FEA the blade at each setting to confirm deflection and the resulting change in roll rate contribution (1.24% to 1.34% across the range). 5. Design retention: a machined square boss and bore to minimise backlash, a threaded stud for blade retention, and a transition-fit needle bearing for bar mounting. 6. Confirm the resulting LLTD range on the car.

Full Material List

Steel.

Reoccuring issues

None recorded. This part has no entry in Knowledge_Transfer/Issue Logging/Fault Vault.xlsx, in either Issue Log.xlsx, in CR22/Issue Tracking/Shakedown 7-15-23.xlsx, or in any design review issue list found in CrimsonStorage or Box.

Properties

Dimensions called out on the cost report drawings. These are the figures printed on the drawing, not a labelled specification; open the drawing itself for what each one refers to. Torsion Bar Ends (as drawn): 10.16, 0.40, 8.48, 0.33, 4.10, 0.16, 2.25, 0.09, 31.75, 1.25 Source: Cost report drawings: CR22/Suspension/Design/01_Cost_Report/Cost Report Drawings/Suspension & Shocks/Front ARB Torsion Bar/Torsion Bar Ends.pdf Quantity per car, as costed: 2

Still to document

Nothing in CrimsonStorage covers these yet.