Driveline System

WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

The source of the drivetrain's power is generated by the engine and delivered to the transmission. The driveline transfers the engine torque through the driveshaft to the axle.

On 2-wheel drive vehicles, power is transmitted through the transmission to the driveshaft and then to the rear axle.
On all wheel drive vehicles, power is transmitted through the transmission and continuously proportioned to the front and rear axles through the transfer case.

The rear driveshaft is connected to the output shaft of the transmission and to the rear axle. The front driveshaft is connected to the transfer case and to the front axle. Universal joints and CV joints are used at the ends of the driveshaft to allow for angular motions. Slip-yokes are used to allow for any changes to the length of the driveshaft. The engine torque enters the axle through the drive pinion, which rotates the ring gear. The ring gear is mounted to the differential case, which contains the gears that transmit power to the rear axle shafts or front halfshafts. These shafts rotate the drive wheels.

Vehicles have the following types of driveshafts:

One-piece rear driveshaft with two U-joints and a front slip-yoke.
One-piece front driveshaft with one front U-joint, a slip-yoke and a rear CV joint.

The engine angle is built into the engine mounts. If the engine angle is out of specification, the engine mounts must be inspected for damage.

Fig 1: Identifying Vehicle Certification (VC) Label Example

Courtesy of FORD MOTOR CO.

The vehicle certification (VC) label is located in the driver door jamb. The first two digits of the axle code indicate the rear axle and the third digit refers to the front axle, if so equipped. For additional information on the VC label, refer to IDENTIFICATION CODES .

Fig 2: Identifying Front Axle

Courtesy of FORD MOTOR CO.

A manufacturing date code and a complete part number is stamped on the left carrier arm between the fill plug and axle end. A metal axle identification tag is attached to the differential by a housing cover bolt.

Fig 3: Identifying Tag

Courtesy of FORD MOTOR CO.

CAUTION: The axle identification tag is the official service identifier. Do not damage the tag. Always reinstall the tag after removing it for axle inspection/repair.

The axle identification tag identifies a particular axle design, a specific ratio, and if it is a conventional or limited slip (Traction-Lok®) type. In addition, the plant code will not change as long as that particular axle assembly never undergoes an external design change. If, however, an internal design change takes place during the production life of the axle and that internal change affects parts interchangeability, a dash and numerical suffix is added to the plant code. This means that as an assembly both axles are interchangeable; however, internally they are different. Therefore, each requires different internal parts at the time of repair.