Road Test

WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

A road test is mandatory for any customer concern of noise/vibration that is not verified by the on-hoist check of chassis components. The Vehicle Road Test Evaluation form is arranged to record the conditions heard or felt during this test.

The road test form lists 4 operating conditions or modes in which some axle noises come and go: DRIVE, CRUISE, COAST and FLOAT.

MODE CONDITIONS REFERENCE

Mode	Conditions
DRIVE	Accelerating the vehicle; a definite pressing of the throttle, applying engine torque.
CRUISE	Maintaining a constant speed with the throttle applied.
COAST	Decelerating with the throttle closed.
FLOAT	Controlled deceleration; backing the throttle continually to prevent either braking or accelerating torque from the engine.

Operate the vehicle in all 4 modes and record those in which the noise occurs. Write down the kilometers-per-hour (miles-per-hour) range at which both noise and vibration occur. The transfer case has similar construction to the rear drive axle. Both components exhibit similar noise characteristics. Axle noise can originate from either the transfer case or the rear drive axle. Using a vibration analyzer, evaluate the vehicle between 95-130 km/h (60-80 mph). The transfer case will have objectionable noise frequency above 600 Hz. Objectionable rear drive axle noise frequency will be below 600 Hz.