Procedures

SI33.20-D-0003A Service Information: Check Front Axle Supporting Joint


Due to the fact that supporting ball joints are frequently replaced unnecessarily, we would once again like to point out that checking the supporting ball joints for axial play is not required and is not possible.

The wear characteristics of the supporting ball joints are designed for a vehicle "service life".

This requires an undamaged rubber boot.

This can however be destroyed through inspections using assembly levers or other sharp-edged tools.

As part of the maintenance operations, leaktightness and status tests of the boots must be made to ensure that the supporting ball joint is not permanently damaged by corrosion influences.

For safety reasons, the raising of the vehicle at the transverse control arms and possible damage to the supporting ball joint is not allowed (refer to document AR00.60-D-1000A).

The arrangement of the supporting ball joints in the transverse control arms means that ball pelling, even on a damaged joint, is not possible.





1 Front axle beam
2 Transverse control arms
3 Transverse leaf spring
4 Shock-absorber strut
5 Rack-and-pinion steering
6 Spring limit stop
7 Steering knuckle
8 Support joint

Interrelation of forces at front axle

The Sprinter front axle has been designed such that the leaf end of the fixed transverse leaf springs (3) applies a force "F" to the transverse control arm (2) in every compression and rebound status.

The transverse control arm (2) generates force "F1" to the ball head of the supporting ball joint (8).

When driving the contact force "R" is applied over the steering knuckle (7) with force "R1" to the ball head in the ball socket.

If the vehicle is relieved at the front axle or jacked up, contact force "R" is zero. The suspension strut (4) moves to the rebound buffer and reaches the ball head of the supporting ball joint (8) over the steering knuckle (7) with force "A", the pre-compressed transverse leaf spring (3) acts with force "F" over the transverse control arm (2) and onto the ball socket with force "F1".

This in turn ensures that the ball journal of the supporting ball joints are not tensioned, neither during a driving maneuver nor when jacked up.

The ball of the supporting ball joint (8) is pressed into the ball socket whenever load is applied, an alternating rebound-pressure load does not occur!