939007911 - S018 FRONT SUSPENSION NOISE (KNOCKING)

Whilst driving, especially on unmade roads, there is knocking coming from the front suspension. This diagnosis can only be made after See table . Carry out the latter first.
If the problem is only on one side, carry out the checks and any operations on the appropriate side only.
Results of the tests
0PRELIMINARY CHECKSAll OKProblems encounteredOperation
Having carried out the road test, see the Table    S15 RUMOROSITA'' in condizioni di marciathere was a knocking noise from the front.Continue depending on the circumstances in which the noise occursEnd of diagnosisThe noise disappears when the brake pedal is operatedRestore the correct tightening of the front brake calipers to the steering knuckle.
The noise occurs whilst accelerating or braking with the wheels steered.Move on to Step 3
The noise only occurs during acceleration or brakingMove on to Step 1
The noise appears whilst braking when the road is slightly unevenMove on to Step 3
The noise is also present in other conditionsMove on to Step 1
1OIL LEAKS CHECKAll OKProblems encounteredOperation
Raise the vehicle on a two column lift and check that there are no oil leaks from the shock absorber stem
Slight dampness on the stem is considered normal because there is evaporation during the operation of the shock absorber.
If there is a persistent oil leak on the shock absorber stem, make sure that it is not coming from other parts of the vehicle that are lubricated
Move on to Step 2Leaks from other parts that are lubricatedSearch for the cause of the leak following the appropriate diagnostic procedure
Leaks from the shock absorber stemReplace the shock absorber    Op. 4410A12 FRONT SUSPENSION DAMPER (ONE), LH OR RH - FOR MCPHERSON STRUT SYSTEM - INCLUDES DISMANTLING/REASSEMBLY OF ASSEMBLY AT BENCH - R.R
2INTERFERENCE CHECKAll OKProblems encounteredOperation
Check that there are no signs of interference between the suspension elements or between the latter and the bodyshell.Check that there are no signs of interference between the lower end of the shock absorber bar connecting rod and the front fastening for the crossmember.Also check that there are no signs of interference between the lower track control arm and the lower fork.In particular, check that there are no signs of wear on the suspension springs and that they do not show signs of abrasion.
If the spring shows signs of abrasion, its mechanical properties could be weakened as a result of oxidation
Move on to Step 3Inteference due to incorrect fittingEliminate the interference and restore the correct fastening. If this is not possible, replace the defective components
Abrasions or non conformity of the springReplace the spring    Op. 4410A12 FRONT SUSPENSION DAMPER (ONE), LH OR RH - FOR MCPHERSON STRUT SYSTEM - INCLUDES DISMANTLING/REASSEMBLY OF ASSEMBLY AT BENCH - R.R taking care to fit it correctly
Signs of interference between the lower end of the connecting rod and the crossmember front fasteningPlace a washer no larger than 3 mm between the connecting rod and the bar.
Signs of interference between the lower track control arm and the lower forkReplace the lower track control arm
3TIGHTENING TORQUE CHECKAll OKProblems encounteredOperation
Locate the area of the possible noise source: top or bottom.Starting from the area where the knocking was identified, check See Test    See Test 4410OA CHECKING CORRECT TIGHTENING OF FRONT SUSPENSION

The tightening torques of the fixing bolts for:

  • upper shock absorber fastening to aluminium fork;
  • upper shock absorber fastening to aluminium fork;
  • anti-roll bar to crossmember fastening;
  • fastening of lower/upper end of connecting rods for shock absorber anti-roll bar;
  • inner/outer fastening for front/rear bushes for lower track control arms to crossmember;
  • fastening of upper aluminium fork to bodyshell;
  • fastening for upper track control arm to aluminium fork and steering knuckle;
  • fastening between power assisted steering box rod and steering knuckle;
  • fastening for steering box to crossmember;
  • front/centre/rear fastening between crossmember and bodyshell;
  • brake caliper fastening to steering knuckle;
  • disc shield fastening.
Also check that the anti-slip adhesive band is present where the crossmember is attached to the bodyshell in the middle and at the back
Move on to Step 4Torque tightenings not correctRestore the correct tightness
Adhesive band not presentFit the anti-slip adhesive band
4ANTI-ROLL BAR CHECKSAll OKProblems encounteredOperation
After having disconnected the upper track rod end for the shock absorber connecting rod, check that the anti-roll bar does not rotate freely around the U-bolts securing it to the crossmember.After having disconnected the connecting rod, check that the clearance for the joints is not too large.Move on to Step 5The anti-roll bar turns freely around the U-bolts securing it to the crossmember.Replace the anti-roll bar
Connecting rod joints clearance too great.Replace the connecting rod.
5UPPER TRACK CONTROL ARMS CHECKAll OKProblems encounteredOperation
Check that there is no clearance between the track control arm track rod ends and make sure that the boot is intact.The bolt connecting the track control arm to the steering knuckle must be loosened in order to carry out this operation.Also check the condition of the bushes.Move on to Step 6There is clearance or the boot or the bushes are not intact.Replace the upper track control arm
7LOWER TRACK CONTROL ARMS CHECKAll OKProblems encounteredOperation
Check that there are no glycol leaks from or signs of damage to the arm rear bush.Check that the track rod end clearance is not too large.In order to do so the guard under the engine must be removedOp. 7055B64 ENGINE COMPARTMENT DUST PROTECTION IN FRONT WHEEL ARCH LINER (ONE) LEFT OR RIGHT - R.R.and disconnect the bolt connecting it to the front steering knuckle    Op. 4410B40 LOWER TRACK CONTROL ARM (WITH BALLJOINT) FOR LEFT OR RIGHT FRONT SUSPENSION (ONE) - R+R - CHECK WHEEL GEOMETRY SEPARATELY Also check the condition of the front bushes.
If the spring shows signs of abrasion, its mechanical properties could be weakened as a result of oxidation
Move on to Step 8Glycol leak from the rear bushReplace the lower track control arm
There is clearance or the boot or the bushes are not intactReplace the lower track control arm
6SPRING/SHOCK ABSORBER ASSEMBLY CHECKAll OKProblems encounteredOperation
Check the presence and condition of the rubber support seals for the upper/lower spring.The shock absorber must be removed in order to carry out this operationOp. 4410A10 L/H OR R/H FRONT SUSPENSION SPRING/DAMPER UNIT (ONE) - R+R - CHECK WHEEL GEOMETRY SEPARATELY IF NECESSARYchecking that the stem projects evenly after the application of manual compression.Move on to Step 7Upper/lower rubber seals not intact.Replace the rubber seals
Stem reascendence irregular.Replace the shock absorberOp. 4410A10 L/H OR R/H FRONT SUSPENSION SPRING/DAMPER UNIT (ONE) - R+R - CHECK WHEEL GEOMETRY SEPARATELY IF NECESSARY
8CHECK ON CORRECT OPERATIONAll OKProblems encounteredOperation
Check that the fault is no longer presentEnd of diagnosisThe fault persistsThe fault is due to another system (engine, clutch, differential). Search for the cause in one of these systems, following the appropriate diagnostic procedures