FAW Rear Axle Drive Shaft: Deconstructing the 8 Critical Assemblies

Welcome to this critical technical guide on the FAW Rear Axle Drive Shaft (Part No. 2201010-1050). This is the main propeller shaft assembly for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This component is the final, essential link that transmits the engine’s torque from the transmission to the drive axle.

The FAW Rear Axle Drive Shaft is a high-torque, high-speed rotating assembly that must operate at a constantly changing angle as the truck’s suspension moves. This “logic” is achieved through its ‘Universal Joint Assemblies’ (2201030-1050) and its ‘Splined Yoke’ slip-joint.

This in-depth guide is an essential resource for professional driveline technicians and fleet managers. We will deconstruct the entire FAW Rear Axle Drive Shaft into its 8 main serviceable component groups, including the main shaft tube, the U-joints, the yokes, and the critical, “as-needed” shims used for precision balancing.

Core Component: The Driveshaft Assemblies (2201010-1050 & 2201060-1050)

The heart of this system is the ‘Rear-axle driveshaft & universal joint assembly’ (2201010-1050), which is the complete, balanced FAW Rear Axle Drive Shaft. This is the main “propeller shaft” that connects the transmission’s output flange to the rear axle’s input flange.

This component is a precision-engineered, hollow steel tube (‘Inter-axle driveshaft welding fork & spline sleeve assy’, 2201015-80A). It must be both incredibly strong (to handle the engine’s full multiplied torque) and perfectly balanced. Any imbalance in this long, high-speed shaft would create a severe, speed-dependent vibration that would shake the entire truck and destroy the transmission’s output bearing.

This FAW Rear Axle Drive Shaft is listed as a “sub-assembly” (2201060-1050), which includes all the yokes and U-joints. A critical design element is its “critical speed”—the RPM at which a shaft’s own harmonic frequency will cause it to wobble violently, like a jump rope. This FAW Rear Axle Drive Shaft is engineered with a specific diameter and wall thickness to ensure its critical speed is far higher than the truck will ever achieve.

The “Logic” 1: Universal Joints (2201030-1050)

The “logic” of the FAW Rear Axle Drive Shaft is its ability to transmit full rotational power at a constantly changing angle. This is achieved by the ‘Cross & needle bearing assy’ (2201030-1050), also known as the Universal Joint or “U-joint.” The parts list calls for two of these, one for each end of the shaft.

This component is a “double hinge.” It consists of a central “cross” or “spider” with four precision-ground, hardened steel arms (trunnions). Each trunnion is fitted with a “cap” that contains dozens of small “needle roller bearings.” These four caps are then secured into the “yokes” (the U-shaped ends) of the driveshaft and the axle flange.

This design allows the FAW Rear Axle Drive Shaft to “bend” up and down as the suspension articulates, perfectly accommodating the movement. A critical aspect of the FAW Rear Axle Drive Shaft is **”phasing.”** The yokes at both ends of a single shaft must be installed in perfect alignment. If they are “out of phase” (misaligned), the U-joints will not cancel each other’s vibrations, leading to a severe “shudder” on acceleration and rapid failure.

The primary failure mode for a U-joint in the FAW Rear Axle Drive Shaft is lack of lubrication. The needle bearings inside the caps require periodic greasing. If they run dry, they will be destroyed by friction, causing a “chirping” noise (that varies with road speed) or a “clunk” when shifting. A seized U-joint will cause a catastrophic failure of the FAW Rear Axle Drive Shaft.

The “Logic” 2: The Slip-Joint Assembly (2201050-1050)

The second “logic” of the FAW Rear Axle Drive Shaft is its ability to change length. This is handled by the ‘Splined yoke & universal joint assy’ (2201050-1050), which is the “slip joint” or “slip yoke.”

As the rear axle moves up and down on its springs, the distance between the transmission and the axle’s input flange *changes*. The axle “swings” in an arc, moving slightly closer and farther away from the transmission.

This “slip joint” (a “female” splined yoke) slides over the “male” splines on the main shaft (‘Inter-axle driveshaft welding fork & spline sleeve assy’, 2201015-80A). This allows the FAW Rear Axle Drive Shaft to expand and contract like a telescope, perfectly compensating for this suspension movement.

Without this slip joint, the FAW Rear Axle Drive Shaft would be a solid, fixed length. The first large bump in the road would cause the axle’s movement to either “pull” the shaft apart or “ram” it forward, destroying the transmission’s output bearing or the axle’s pinion bearing. A worn slip joint, often from a lack of grease, is a common source of a “clunking” sound when the truck starts or stops.

Precision Alignment: Circlips and Shims

The final components of the FAW Rear Axle Drive Shaft are the precision alignment parts. The parts list calls for 8 ‘Circlips’ (2201041-80A through 2201048-80A) and multiple sets of ‘Shims’ (2201071-1H series and 2201078-1H series).

The ‘Circlips’ are the snap-rings that are used to retain the U-joint’s bearing caps within the yokes. The fact that there are 8 different part numbers for 8 circlips indicates that these are **selective fit** circlips. This means they come in minutely different thicknesses. A technician must use these to perfectly center the U-joint “cross” within the yoke, preventing any side-to-side “play” that would cause vibration.

The ‘Shims’ (marked “按需” – “as needed”) are even more critical. These are paper-thin, precision-cut shims used for **dynamic balancing**. During manufacturing, the complete FAW Rear Axle Drive Shaft is spun on a balancing machine. The machine detects tiny “heavy spots,” and the technician adds these shims (often under the U-joint caps) to achieve perfect balance.

It is **critically important** to never lose, mix up, or fail to reinstall these shims. Removing even one of these “as needed” shims will destroy the shaft’s balance, leading to a severe vibration that can only be fixed by having the entire FAW Rear Axle Drive Shaft re-balanced by a driveline specialist.

FAW Rear Axle Drive Shaft Parts List

The following table provides the complete, detailed breakdown of all 8 component groups identified in the ‘Rear Axle Drive Shaft’ diagram for the FAW CA4251P66K24T1A3E5 tractor. This FAW Rear Axle Drive Shaft is a precision-balanced assembly.

Technical Specifications and Assembly Context

The specifications for the FAW Rear Axle Drive Shaft are defined by its function as a high-torque, high-speed, flexible power transmission system. This FAW Rear Axle Drive Shaft is a precision-balanced component.