Audi Cars 1999-05

Strut (MacPherson Strut) Assembly

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Overhaul (Coil Spring Removal & Installation)



If the strut housing retains the dampener assembly with a threaded cap, a dampener insert may be available separately from the entire strut assembly. Consult you local parts vendor or shock absorber manufacturer for availability and specific installation details.

Some special tools will be necessary to disassemble the strut such as a suitable spring compressor, a sturdy vise, and a tool capable of removing the cap nut, such as a large pipe wrench.


CAUTION
The coil spring is very strong and under considerable pressure. If the correct tools and techniques are not available, Do NOT attempt this job. Improper handling of coil springs can cause serious or fatal injury.

  1. Remove the strut.
  2.  
  3. Anchor the strut in a vise so it cannot move and attach the spring compressor.
  4.  
  5. Remove the spring.
  6.  
  7. Use a suitable pipe wrench to remove the threaded collar from the top of the strut. Remove the strut from the vice and pour the fluid into a suitable drain pan.
  8.  
  9. Remove the strut rod and discard all the internal parts.
  10.  

To install:

  1. Most replacement inserts are a self-contained gas pressure shock absorber. Follow the shock insert manufacturers directions for installation of their inserts. Typically it may be recommended to pour about 2 ounces of fresh ATF into the strut housing and then install the new insert. The fluid will help dissipate heat and extend the life of the insert.
  2.  
  3. Install the threaded collar and tighten it to 30 ft. lbs. (40 Nm).
  4.  
  5. Fit the spring into place, install the upper seat and start the nut onto the rod. It may be easier to tighten the nut before removing the spring compressor. Tighten the nut to the manufacturer's recommended torque then carefully remove the spring compressor and install the strut assembly.
  6.  

Please refer to the front shock absorbers for overhaul procedures.

Removal & Installation



  1. Note the radio security code and disconnect the negative battery cable.
  2.  
  3. Loosen the front lug bolts slightly, but Do NOT remove.
  4.  
  5. Raise and safely support the vehicle.
  6.  
  7. Remove the front wheel(s).
  8.  
  9. Remove the grommets under the hood to access the upper strut mounting fasteners, then loosen and remove the fasteners.
  10.  
  11. Remove the ABS sensor electrical cable from the support bracket near the brake caliper.
  12.  
  13. Loosen the pinch bolt and nut for the upper control arms and remove the arms from the bearing holder (knuckle). Do NOT pry or wedge the open the slotted area of the bearing holder.
  14.  
  15. Pivot the bearing holder assembly forward and remove the lower strut clevis mounting bolt and nut, then remove the strut assembly.
  16.  



Click image to see an enlarged view

Fig. Loosen and remove the pinch bolt (1) and remove upper arms (2). Do NOT loosen or remove the tie rod end (Nos. 3 and 4)

To install:

  1. Installation is in reverse order of removal noting the following:
  2.  
  3. Install the strut assembly with the spring perch drain hole facing toward the middle of the vehicle.
  4.  
  5. Tighten the mounting fasteners as follows:
  6.  


    Bearing holder upper control arm pinch bolt: 30 ft. lbs. (40 Nm)
     
    Front strut-to-control arm: 66 ft. lbs. (90 Nm)
     
    Front upper strut-to-body: 15 ft. lbs. (20 Nm)
     
    Wheel lug bolts: 89 ft. lbs. (120 Nm)
     


  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:
    NOTE
    When removing the strut, be sure not to damage the CV-joint boot.



    Front wheels
     
    Rubber grommets from the plenum chamber
     
    Upper strut-to-body mounting nuts
     
    Anti-lock Brake System (ABS) wheel speed sensor wire from the brake caliper bracket
     
    Upper control arm pinch bolt and both upper control links
     
    Guide link ball joint, by swiveling the wheel bearing housing aside
     
    Lower strut mounting bolt
     



    Strut
     

  4.  

To install:


NOTE
The bonded rubber bushing can only turned to a limited extent. The bolted connections between the suspension strut and the lower track control links should therefore only be tightened when the vehicle is standing on the ground.

  1. Install or connect the following:
    NOTE
    It may be necessary to hold the ball joint stud with a 4mm hex wrench.



    Strut by positioning it so that the spring hole plate faces the middle of the vehicle. Torque the bolt to 66 ft. lbs. (90 Nm)
     
    Upper control links to the wheel bearing housing. Torque the pinch bolt to 30 ft. lbs. (40 Nm)
     



    Ball joint. Torque the nut to 74 ft. lbs. (100 Nm)
     
    ABS wheel speed sensor wire into the brake caliper holder
     
    Upper strut-to-body nuts. Torque them to 15 ft. lbs. (20 Nm)
     
    Rubber grommets into the plenum chamber
     
    Front wheels
     

  2.  
  3. Test drive the vehicle.
  4.  
  5. Check and/or adjust the front alignment.
  6.  



Click image to see an enlarged view

Fig. Exploded view of the front strut mounting-A6

  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:
    WARNING
    Do not damage CV boot during this process.



    Plenum chamber cover
     
    Battery
     
    Front wheels
     
    Rubber grommets in plenum
     
    Support lower control arm with a strong jack
     
    Top mounting nuts for strut through plenum openings
     
    ABS sensor cable from bracket on caliper
     
    Steering knuckle upper mounting nut (innermost nut only; do not loosen outer bolts)
     
    Guide link from wheel bearing housing
     



    Lower strut mounting bolt
     
    Strut assembly from vehicle.
     

  4.  

To install:

  1. Installation is the reverse of the removal procedures.
  2.  
  3. Install or connect the following:

    Lower strut mounting nut to 66 ft. lbs. (90 Nm)
     
    Upper links in wheel bearing housing nuts to 30 ft. lbs. (40 Nm)
     
    Joint bolt nut to 74 ft. lbs. (100 Nm)
     
    Strut upper mounting bolts (new) to 15 ft. lbs. (20 Nm)
     

  4.  

  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:

    Front wheels
     
    Coupling rod from suspension strut on both sides
     
    Spring clip from bracket and detach brake hose
     
    Speed sensor wiring
     
    Noise insulation panel
     
    Drive axle from flange shaft/transmission
     
    Secure drive axle with wire
     
    Wheel bearing housing/suspension strut bolt connection
     

  4.  
  5. Insert special tool 3424 into slot on wheel bearing housing and ratchet around 90°.
  6.  
  7. Press the brake disc by hand in direction of suspension strut
  8.  
  9. Remove the wheel bearing housing from strut tube downward.
  10.  
  11. Tie wheel bearing housing to subframe with wire
  12.  
  13. Remove hex-nut for top strut mounting .
    NOTE
    When removing the strut, be sure not to damage the CV-joint boot.

  14.  

To install:


NOTE
Before inserting suspension strut, coat strut mounting with installation lubricant G 294 421 A1.

  1. Install the strut to the upper mounting. Torque the bolt to 44 ft. lbs. (60 Nm).
  2.  
  3. Place suspension strut on wheel bearing housing.
  4.  
  5. Carefully lift wheel bearing housing using transmission jack far enough until bolt for suspension strut/wheel bearing housing can be inserted.
  6.  
  7. Press the brake disc by hand in direction of the suspension strut.
  8.  
  9. Remove spreader 3424 from wheel bearing housing.
  10.  
  11. Strut must be installed up to stop in wheel carrier. Torque the bolt to 44 ft. lbs. (60 Nm) plus 90°.
  12.  
  13. Install the ball joint. Torque the bolt to 55 ft. lb. (75) Nm).
  14.  
  15. Reverse the removal procedure for the remaining components.
  16.  
  17. Test drive the vehicle.
  18.  
  19. Check and/or adjust the front alignment.
  20.  

Testing & Inspection



The purpose of the shock absorber or dampener portion of the strut assembly is simply to limit the sudden motion of the spring during compression and rebound cycles. If the vehicle is not equipped with these motion dampers, the up and down motion would multiply until the vehicle was alternately trying to leap off the ground and to pound itself into the pavement.

Contrary to popular rumor, unless gas charged, the shocks Do NOT affect the ride height of the vehicle. This is controlled by other suspension components such as springs and tires. Worn dampeners can affect handling; if the front of the vehicle is rising or falling excessively, the 'footprint' of the tires changes on the pavement and steering is affected.

The simplest test of the dampener is simply push down on one corner of the unladen vehicle and release it. Observe the motion of the body as it is released. In most cases, it will come up beyond it original rest position, dip back below it and settle quickly to rest. This shows that the damper is controlling the spring action. Any tendency to excessive pitch (up-and-down) motion or failure to return to rest within 2-3 cycles is a sign of poor function within the shock absorber. Oil-filled dampers may have a light film of oil around the seal, resulting from normal breathing and air exchange. This should NOT be taken as a sign of failure, but any sign of thick or running oil definitely indicates failure. Gas filled struts may also show some film at the shaft; if the gas has leaked out, the shock will have almost no resistance to motion.

Each strut or if equipped with cartridge type struts, the dampener insert can be replaced individually, although it is recommended that they be changed as a pair (both front or both rear) to maintain equal response on both sides of the vehicle. Chances are quite good that if one has failed, its mate is weak also.


NOTE
When replacing struts or inserts, always make sure they are a matched set, or for one strut, make sure it matches the strut not being replaced.



Click image to see an enlarged view

Fig. When fluid is seeping out of the dampener, it's time to replace the strut

Please refer to the front shock absorbers for testing procedures.

While each shock absorber can be replaced individually, it is recommended that they be changed as a pair (both front or both rear) to maintain equal response on both sides of the vehicle. Chances are quite good that if one has failed, its mate is weak also.

 
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