What this check covers
Selected transmission, final-drive, rear-assembly and steering pathways for supported light vehicles. ICVs, electric/hybrid conversions, motorcycles and other specialised conversions need separate assessment.
The result covers the selected requirements and evidence entered. It does not certify the vehicle or confirm its overall compliance.
What you need
- Original and fitted gearbox, axle, shaft and steering component identities.
- Complete same-model manufacturer-option records where relied on.
- Mounting, shaft construction/balance, full-travel and control-system records.
- Related brake, suspension, wheel, track and speedometer changes.
Understand the requirements
Identify each change separately
Record the gearbox or transaxle, final-drive gears, complete axle/differential assembly, shafts and steering components. A same-model manufacturer option requires its associated parts, correct controls and management, matching speedometer drive and original installation conditions.
Transmission, gears and rear assemblies
A non-option transmission or final-drive gear ratio indicates LB1 assessment. A replacement or modified rear live axle or chassis-mounted final-drive assembly indicates LB2. Rear brake changes made with that assembly also need the applicable LG1/LG2 assessment; rear suspension changes need the applicable LS5/LS6 assessment. Those interacting systems are not approved by this check.
Keep torque/load suitability, mounts, shaft construction and balance, operating angles, slip/spline travel and full-travel clearances documented. Hollow shafts must not be made by butt-welding tube sections together. Permanently locked, welded or spool differentials are not permitted under the selected requirements. A proprietary part-time locker needs control from the normal driving position; that operating condition does not establish a certification exemption. Retain its complete manufacturer-option basis or establish the applicable modification-code coverage. Automatic or other aftermarket devices require their actual operation and pathway to be reviewed.
Steering conversions and wheels
A complete manufacturer optional power-steering system may use its basic pathway when all standard components and mounting hardware for that model are used. Different-model or modified power steering and rack conversions indicate LS3 design and LS4 modification assessment. Left-to-right steering conversion indicates LS1/LS2; right-to-left or dual steering indicates LS3/LS4. Actual design eligibility, VSB4 requirements where applicable, geometry, structure and associated controls remain for engineering review.
Replacement steering wheels need applicable ADR 10/69 evidence and vehicle-specific hub, airbag and restraint compatibility. For ADR 69 vehicles, retain the identical same-model factory-option basis or replacement manufacturer certification for that make/model. The guidance recommends at least 330 mm diameter; a smaller wheel is referred for specialist review. Removable or quick-release wheels must not be fitted.
Evidence and assessment limits
Retain original/fitted specifications, factory-option references, drawings and design numbers, fitting records, shaft/balance reports, steering and full-travel inspection records, applicable sensor/interlock checks and electronic-system evidence. Welded, heated, bent or chrome-plated axle, suspension or steering components need the precise Queensland restriction and engineered approval scope established with TMR or an Approved Person; a national-code provision alone does not establish an exemption.
Identify height, track, wheel/tyre and suspension changes separately. Queensland uses its applicable QCOP high-lift pathways in place of national LS7/LS8. This calculator does not calculate shaft strength or critical speed, steering geometry, braking performance, airbag or ESC compliance. ICVs, electric/hybrid conversions, motorcycles, trailers, heavy vehicles and other specialised conversions need separate assessment.
Worked example
A rear assembly can affect several systems
A replacement rear assembly may need its LB2 assessment, while changed brakes and suspension need their applicable LG and LS assessments. An outcome for the assembly does not approve the interacting systems.
Read this example within the selected scope. The actual installation and supporting evidence determine the finding.
Official sources and review
- Queensland Road Vehicle Modification Handbook
- TMR approved vehicle modification codes
- NCOP Section LB — Transmission
- NCOP Section LS — Suspension and Steering
- TMR Minor modifications
Sources reviewed 20 October 2026. This guide uses national standards, Queensland modification codes and the February 2026 Minor modifications instruction. Later changes to that instruction have not been confirmed. Confirm current requirements for your vehicle with TMR or an appropriately accredited Approved Person.