A heavier, more resonant version of whine, typically heard from drive axles at highway speed. A howl that appears under acceleration points to the drive side, while one on deceleration points to the coast side, and a howl at a specific speed often means the mesh frequency has hit a body or driveline resonance. Common causes are wrong pinion depth, worn gears and loose pinion bearing preload.
Rear end howls on decel at sixty, coast side pattern must be off, or the pinion bearings have gone loose.
Also heard as
- axle howl
- gear howl
Related terms
Whine
A steady, pitch-changing tonal noise from gears, rising with speed and caused by tooth meshing errors.
Pinion depth
How far the hypoid or bevel pinion sits along its axis toward the gear, set with shims behind its bearing.
Ring and pinion
Shop name for the hypoid final drive in a vehicle axle, named by its ratio, such as 3.73 or 4.10.
Drive side
The tooth flank that carries load when power flows in the normal direction; the opposite flank is the coast side.