Crimson Racing Wiki

Bearing Holder

Subteam: SuspensionSubsystem: ARBAssembly: Rear ARB Torsion BarCars: CR22, CR25, CR26I

Purpose

Support the ARB torsion bar in the frame so it rotates freely.

Function

Houses a transition-fit needle bearing that lets the bar twist without binding.

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.

Manufacturing Process

Milled on the CNC.

Full Material List

Aluminium housing, INA-SCE88 1/2 in ID needle roller bearing (2000 lb static radial capacity against a 200 lb maximum static load seen).

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

CAD mass, CR22 master assembly: 0.032 lb (0.014 kg), 3 instances, 0.095 lb total. CG at X 17.10 in, Y -2.16 in, Z 5.25 in in vehicle coordinates. (CAD component: MirrorBearing Holder) 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. Spherical Bearing Holder (as drawn): 0.64, 1.59, 1.27, 2.03, 2.17, 4.35 Bearing Holder (as drawn): 19.051.91, 9.53, 0.95, 24.13, 2.41, 43.18, 4.32, 4.17, 0.42, 12.70 Source: SolidWorks mass model exports: CR22 (5 May 2024), CR25 (4 Jul 2025), CR26I (30 Jul 2025), CR26E (22 Mar 2026) | Cost report drawings: CR22/Suspension/Design/01_Cost_Report/Cost Report Drawings/Suspension & Shocks/Front A-Arms/Spherical Bearing Holder.pdf; CR22/Suspension/Design/01_Cost_Report/Cost Report Drawings/Suspension & Shocks/Rear A-Arms/Spherical Bearing Holder.pdf; CR22/Suspension/Design/01_Cost_Report/Cost Report Drawings/Suspension & Shocks/Rear ARB Torsion Bar/Bearing Holder.pdf Quantity per car, as costed: 2

Still to document

Nothing in CrimsonStorage covers these yet.