The most common signs that a transmission is slipping include the revolutions-per-minute gauge being above 3,500, the car taking too long to coast or a delay in acceleration. Common causes of a transmission slip range from poor cleanup to defective parts.
One of the most common causes of a transmission slipping is low automatic-transmission fluid. A worn-out or broken band can also cause a transmission slip. A manual transmission can sometimes slip if the gear shift is defective, in which case either a new shift or a readjustment would be required. Both automatic and manual transmissions slip if the clutch wears too thin.