Road Test Quick Checks

WARNING: IF ONLY ONE DRIVE WHEEL IS ALLOWED TO ROTATE, SPEED MUST BE LIMITED TO A MAXIMUM SPEEDOMETER READING OF 55 KM/H (34 MPH) SINCE THE ACTUAL WHEEL SPEED WILL BE TWICE THAT INDICATED ON THE SPEEDOMETER. EXCEEDING A SPEED OF 55 KM/H (34 MPH) OR ALLOWING THE DRIVE WHEEL TO HANG UNSUPPORTED COULD RESULT IN TIRE DISINTEGRATION, DIFFERENTIAL FAILURE, WHICH COULD CAUSE SERIOUS PERSONAL INJURY AND EXTENSIVE VEHICLE DAMAGE.

START ROAD TEST HERE
1. 24-80 kph (15-50 mph): With light acceleration, a moaning noise is heard, and possibly a vibration is felt in the floorpan. It is usually worse at a particular engine speed and at a particular throttle setting. It may also produce a moaning sound. B
2. High Speed: With slow acceleration and deceleration, a shake is sometimes noticed in the steering wheel steering column tube, seats, floorpan, trim panels or front end sheet metal. It is a low-frequency vibration. It may or may not be increased by applying brakes lightly. A: High Speed Shake
3. High Speed: A vibration is felt in the floorpan or seats with no visible shake, but with an accompanying sound or rumble, buzz hum, drone or booming noise. Coast with transmission control selector lever in NEUTRAL and engine idling. If vibration is still evident, it may be related to:
- wheels .
- tires.
- front disc brake rotor.
- rear brake drums.
- wheel hub.
- wheel bearing.
- axle companion flange runout.
- driveshaft balance.
4. High Speed: A vibration is felt whenever the engine reaches a particular rpm. It will disappear in neutral coast. The vibration can be duplicated by operating the engine at the problem rpm while the vehicle is parked. It can be caused by any number of components. D

ROAD CONDITIONS
The type of road and its surface condition are important factors in the road test. A smooth asphalt road that allows driving over a range of speeds is best. The brushed concrete road surface found on many expressways and the coarse aggregate sometimes found in concrete can mask many vehicle noises and make NVH diagnosis difficult.