A clipped term for the differential, the mechanical unit connecting the driveshaft to the axle shafts. It transmits engine torque to the wheels while allowing the outside wheel to spin faster than the inside wheel in a corner. Mechanics regularly service these by draining the heavy gear oil from the housing and inspecting the ring and pinion gears for wear.
Heard on the job
We need to pull the rear cover and check the diff gears for metal shavings.
Related terms
Diff lock
A mechanism that forces both wheels on an axle to turn at the exact same speed.
Limited-slip differential
A differential that transfers torque to the wheel with the most traction to prevent wheelspin.
Drivetrain
The complete group of components that generate power and deliver it to the road surface.