6.1 Service & Parking Brake Performance

Test the outcomes the VIRM specifies

Brake performance may be established with approved equipment or a controlled road method permitted by the inspection procedure. Do not claim that every vehicle must use a roller brake tester or that the VIRM mandates an invented roller slip percentage. The certification question is whether the service and parking brakes meet the stated performance and control criteria.

Service-brake stopping performance

Without engine assistance, the current reasons for rejection include failure to stop from 30 km/h within:

The older 40% and 18% values are configuration/date exceptions, not a general lower standard for every pre-1990 vehicle. The guide should not invent a 45% category.

The brake must apply in a controlled and progressive way. Reject severe vibration affecting control, failure to release immediately after the pedal is released, or directional-control effects such as swerving or one side applying noticeably later.

Axle balance

During the brake application, balance must not vary by more than 20% between wheels on a common axle. When using measured wheel forces, apply the tester procedure and formula it specifies consistently. Do not add a made-up minimum force per individual wheel when the VIRM criterion is total performance and balance.

A calculated 26.7% difference using (higher minus lower) divided by higher exceeds 20% and fails. But ensure readings were taken at comparable stages and that the approved equipment was used correctly.

Parking brake

The parking brake must be present (subject to the class LE exception) and act on the required axle. Performance is acceptable through the applicable VIRM method. Reasons for rejection include failure to:

• stop within 18 m from 30 km/h (20% average efficiency);
• hold the vehicle at rest on a 1-in-5 slope; or
• hold all wheels on a common axle stationary against an attempt to drive away.

The page does not require a separate “both uphill and downhill” test in every case. Use the approved method safely. Reject unusual difficulty applying or releasing the brake and adverse directional control where the specified vehicle/date condition applies.

Safe, valid testing

Confirm tyre condition, load, road/tester conditions, transmission and driveline limitations, and manufacturer precautions before testing. Four-wheel-drive, limited-slip, hybrid, EV, and electronic parking-brake systems may require a particular approved method. A test that could damage the vehicle is not valid simply because it produces numbers.

Calibrate brake-test equipment at least every 12 months, or more often according to the manufacturer, and after accuracy-affecting maintenance. Follow the equipment instructions for positioning, zeroing, and interpretation rather than asserting that every decelerometer must be tested at an unsupported 30–35 km/h protocol.

Decision sequence

1. Identify brake design and any applicable exception.
2. Inspect components before dynamic testing.
3. Select a safe, approved test method.
4. Assess service stopping performance, progressiveness, direction, release, vibration, and balance.
5. Assess the parking brake through an applicable method.
6. Retain the measured evidence and record the precise failure.

Scenario

A standard 2018 passenger vehicle stops from 30 km/h in 8 m without pulling. Smoothness does not cure inadequate performance: it exceeds the 7 m limit. A vehicle whose service brake is genuinely designed to act on fewer than four wheels would use the separate 9 m criterion.

Read numbers in context

Stopping distance is measured over the braking phase under the approved method, not from the moment an inspector thinks about applying the pedal. Speed accuracy, surface, gradient, tyre condition and engine assistance can invalidate a test. Retest only when the first run was procedurally invalid—not to search repeatedly for a passing number.

For an axle balance calculation with 3.0 kN and 2.2 kN, the difference is 0.8 kN; dividing by the higher 3.0 kN gives 26.7%, which fails the 20% limit. Keep units consistent and do not divide by the lower reading or by total axle force unless the approved tester’s method expressly defines that calculation.