Alignment bay geometry is the physical relationship among the vehicle support surfaces, plates, lift structure and the aligner’s calibrated measurement reference.
The vehicle must sit on stable support surfaces.
Turn plates and rear slip plates must move and lock correctly.
Mechanical levelness and software reference are related but not identical.
Bay verification should be part of installation and service.
The bay influences the vehicle
An alignment measures wheel geometry while the vehicle is supported by the bay. If support heights differ, a vehicle can sit with unintended roll, pitch or suspension load. Binding plates can prevent the tires and suspension from settling naturally. These conditions can change readings even when the aligner itself is functioning correctly.
Mechanical plane and measurement plane
A level lift is a strong foundation, but camera systems can also use calibrated reference geometry to understand the measurement space. Software compensation can improve measurement robustness within its design limits; it does not repair a loose lift, damaged runway, incorrectly installed plate or unsafe bay.
Turn plates and rear slip plates
Turn plates allow steering movement during caster sweep. Rear slip plates allow the rear tires and suspension to settle without lateral binding. Their lock state should match the stage of the workflow. Dirt, corrosion, damaged bearings or incorrect locking can create inconsistent results.
The aligner, lift, plates and vehicle are one measurement environment. Diagnose the environment before blaming a single component.
Diagnostic reference
| Finding | Possible meaning | Next check |
|---|---|---|
| Cross-camber changes with vehicle position | Support-height or runway geometry issue | Verify the bay and repeat at controlled position |
| Readings change after plates are released | Suspension was bound | Inspect and service plate movement |
| Caster sweep is difficult or inconsistent | Turn plate lock, centering or capacity issue | Check plate setup and vehicle position |
Workshop procedure
- Inspect lift structure, anchors and runways according to lift instructions.
- Verify turn plates and rear slip plates are correctly installed.
- Check plate locks, movement and cleanliness.
- Confirm the aligner reference calibration for the bay.
- Use a known vehicle or verification fixture when specified.
- Document the bay condition after installation or major service.
Frequently asked questions
Can software compensate for an unlevel lift?
Some systems can establish a calibrated measurement reference that reduces sensitivity to modest bay geometry. This does not remove the need for a safe, stable and correctly installed lift.
Why must slip plates be unlocked during parts of alignment?
They allow tire and suspension movement so the vehicle can settle without artificial lateral force.
When should the bay be rechecked?
After lift movement, plate replacement, impact, structural service or unexplained repeatability changes, and as required by the equipment procedures.
Technical reference · Published 17 July 2026 · Review product documentation before service.