Gear Whine

Gear whine is a high-pitched humming or whining sound that rises and falls with speed. It comes from gear teeth that do not mesh as cleanly as they should, often because of wear, incorrect backlash, worn bearings or low or degraded oil.

Some straight-cut gears, for example in primary drives or race gearboxes, whine a little by design, so a faint noise is not always a fault. A whine that is new, gets louder or appears in only one gear deserves attention.

Start by checking the oil level and condition. If the noise persists, the gearbox may need to be opened to inspect the gears, bearings and shims before a small problem becomes a broken gear.