Troubleshooting, front axle

Defective wheel control joints

Wheel control joints are only defective in rare cases. For this reason, the wheel control joints may only be replaced if this is required due to the measurement results after a running a test using the electronic axial play measuring device.

To verify proper performance of the test, the diagnosis report (paper printout) must be enclosed with the warranty or goodwill application.

Noises in the area of the front axle

Noises in the area of the front axle can have the following causes:

• Defective hinged bracket.
  
• Hydraulic bearing on the control arm causes noise
  Note: in individual cases, the hydraulic bearing on the control arm can cause a ”rattling sound” without any visible damage to the bearing being detected.
  Test: The ”rattling” noise occurs when the front wheels move at walking speed over a small obstacle (4 - 8 cm, e.g. kerb). The noise can occur on the left-hand or right-hand wheel.
  Note: Replace the hydraulic bearing only if there is a customer complaint. The hydraulic bearing only has an acoustic problem, but it remains safe for operation.
  
• Heat protection shield on the right-hand hydraulic bearing of the control arm is bent
  Note: The heat protection shield must be pre-tensioned on the bracket of the hydraulic bearing. There is an impression so that the plate only makes contact at one point. Noises can be caused by oscillations if the plate is not pre-tensioned but has a small gap to the bracket.
  
• Engine bonnet causes noises.
  Note: The guide or stop pin in the hinge of the engine bonnet needs to be greased, as otherwise rattling noises occur.
  
• Plunger in the steering gear causes noise
  Note: The noise only occurs when the vehicle has been driven and operating temperature reached and on driving over irregular road surfaces with the left-hand wheel.
  Test: Test drive until the vehicle is at operating temperature. Drive the vehicle onto the lifting platform and raise it until the centre point of the wheel is at chest height. Shake the left-hand wheel alternately forwards and backwards. If a knocking sound is clearly audible, associated with significant play at the wheel, the play of the plunger in the steering gear is too great. In addition, a second person should place their hand on the left-hand steering track rod. If the play of the plunger is too great, knocking can be felt clearly when it is shaken.
  Note: Replace the steering gear only if there is a customer complaint. The steering gear only has an acoustic problem, but it remains safe for operation.
  

Felt play on the front wheel

If checks on the front wheel indicate play, it cannot be assumed as a general principle that there is a defect. The felt play is very frequently only the total of the normal elasticities. If necessary, check each joint individually according to the specifications of the repair instructions (wheel control joint, tie rod joint and axial joint under the gaiter). Always use the electronic axial play measuring device to check the wheel control joint.