Tire Noise
Tire noise can easily be mistaken for differential noise even though
the noisy tires may be located on the front of the vehicle. Tire noise may
change with different road conditions, whereas, differential noise is more
speed and/or torque (load) sensitive. First check for and eliminate tire
noise before proceeding to diagnose a deferential noise.
Wheel Bearings
The following conditions cause a noise similar to tire noise:
| • | Brinelled wheel bearings |
The noise is constant if the noise does not vary on drive or coast and
if the noise still persists when coasting with the transmission in neutral.
This noise does not noticeably change on differing road surfaces to the same
degree as does tire noise. Although not so pronounced, wheel bearing noise
can also be compared to a road surface noise, which is produced when the
vehicle is traveling over uneven or rough road surfaces.
Backlash Clunk
The following conditions cause excessive clunk with acceleration and
deceleration:
| • | A worn differential drive pinion gear |
| • | A worn differential case |
| • | An excessive clearance between the inner cv joint shaft and the
differential side gear splines |
| • | An excessive clearance between the differential side gear hub
and the counterbore in case |
| • | A worn differential pinion and side gear teeth |
| • | An excessive differential drive pinion gear-to-differential ring
gear backlash |
The entire differential assembly should be disassembled and inspected
if it is determined that the differential components are damaged or excessively
worn.
Drive-Line Snap
A snap on sudden start, either forward or reverse, may be caused by
a loose pinion flange.
Engine And Other Contributing Factors
The following noises are occasionally confused with the differential
noises:
| • | Noises which originate from the engine. |
| • | Noises which originate from the transmission. |
| • | Noises which originate from the muffler. |
Perform the following steps to isolate these noises:
- Carefully note the approximate vehicle speed and the conditions
where the supposed differential noise is most pronounced.
- Ensure the vehicle is in a quiet place to avoid interfering noises.
- Ensure the vehicle is stationary.
- Run the engine up and down slowly through the engine speeds that
correspond to the vehicle speeds at which the noise was prominent.
- Observe whether there is any similarity to a differential noise.
- Muffler noises are usually readily identified. The exception being
when a muffler emits a high-pitched periodic whistling noise that may be confused
with a bearing noise.
