How to diagnose steering & suspension faults

Often when motorists think of vehicle safety and performance, they will automatically think about the braking system and engine. However, the power generated by an engine is useless if the driver cannot control the vehicle. Likewise, the effectiveness of the brakes will be impaired if the suspension is poor.

The main function of the suspension system is to maximise the friction between the tyres and road surface whilst steering has the main role of providing stability and good handling.

Typically two main areas require constant inspection. These are the rubber to metal components, such as the track control arms, torque rods, ball joints and the shock absorbers.

Tips for fewer comebacks

  • Check all the mounting nuts and bolts to be sure the problems aren’t being caused by looseness.
  • Inspect any visible parts such as the bushings, ball joints, steering linkages. If you see any damage it will need to be serviced or replaced.
  • Shake the steering wheel quickly, turning it left and right at quarter of full circle. There should be excessive free play or knocking noises. If the car has power steering, do this with the engine running. Check rack and pinion type steering mechanism, as well as steering boots. If any of them are damaged, the part needs to be replaced.
  • If the car makes noises while turning, it could be a sign of a worn ball joint. If the ball joints use a grease nipple, they can wear out if not lubricated properly or are in prolonged use. Worn ball joints should be replaced.
  • Replace the entire ball joint where the rubber boot is split, cracked, damaged or even missing. Never replace the boot only as this can seal in any damaging substances the joint has been exposed to, resulting in increased dust and corrosion.
  • If the suspension bushing is worn out (located at the inner end of the control arms), steering problems and abnormal tyre wear may happen. Replace the bushings in this case.
  • Always tighten components to their correct torque as specified by the VM in its loaded position, not wheel-free, to prevent additional stress when the vehicles is lowered to the ground.
  • Check the wheel alignment after replacing any steering or suspension components to prevent excessive tyre wear. The new parts will have less play and set the wheels at a slightly different angle.

Fault diagnosis

Tie rod end damaged boot

Causes:

  • Use of incorrect tools
  • Contact with oils and fluids or stone impact

Effects:

  • Premature wear of the joint
  • Internal corrosion
  • Abnormal tyre wear

Deformed inner tie rod

Causes:

  • Accident damage

Effects:

  • Incorrect wheel alignment
  • Wandering or general instability
  • Excessive tyre wear on inside or outside edges

deformed-inner-tie-rod

Steering rack gaiter split

Causes:

  • General wear and tear
  • Contamination by oils or fluids

Effects:

  • Possible premature wear of the inner tie rod joint or steering rack
  • Incorrect wheel alignment
  • Abnormal tyre wear

steering-rack-gaiter-split

Wishbone or track control arm worn bush

Causes:

  • General wear and tear
  • Contamination by oils or fluids

Effects:

  • Wandering or general instability
  • Vehicle pulls to one side
  • Knocking

wishbone-track-control-arm-worn-bush

Ball joint excess play

Causes:

  • General wear and tear
  • Water ingress due to damaged boot

Effects:

  • Wandering or general instability
  • Knocking
  • Incorrect wheel alignment

ball-joint-excess-play

Deformed engine mount

Causes:

  • Accident damage
  • Engine oil contamination

Effects:

  • Excessive vibration/knocking

deformed-engine-mount

Corroded wishbone or control arm

Causes:

  • Water or road salt

Effects:

  • In extreme cases component failure and possible loss of vehicle control

corroded-wishbone-control-arm

Link stabiliser sheared ball pin

Causes:

  • Use of incorrect fitting tools (i.e air tools)

Effects:

  • Inability to fit the part onto the vehicle
  • Premature component failure/damage

corroded-wishbone-control-arm

General Tips

  • Replace all damaged parts as required following manufactures instructions and carry out wheel alignment check.
  • Always replace self-locking nuts and bolts and tighten to the specified torque.
  • Use only the correct tools