BMW Z3 Suspension Issues Explained(+7 Tips)

In this brief article we are going to discuss the different BMW Z3 Suspension problems, what the causes are, and Troubleshooting Tips.

Top 7 most common suspension issues in the BMW Z3? 

The most common BMW Z3 suspension issues are:

  • Drifting or Pulling
  • Front Shock Absorber Failure
  • Bouncy Ride
  • Diving during Braking
  • Rear Knocking Sound
  • Front Strut Top Mount Failure
  • Rear Trailing arm bush failure

What suspension does the BMW Z3 have?

Front Suspension

The First generation (2001-2007) of the Z3 is a MacPherson Strut and Lower control Arm with Anti-roll bar. This arrangement is mounted onto a subframe.

Rear Suspension

Though the Z3 is based on the BMW E36 3-Series platform, it uses the rear semi-trailing arm suspension design derived from the older E30 3-Series platform.

Drifting or Pulling

  • While accelerating or decelerating the car, you find that it pulls to either one side
  • Normally happens at 30 mph or more. The problem worsens with speed
  • Poor handling; difficult to maintain a steady line

Troubleshooting Drifting or Pulling

  • The problem has occurred due to ‘Mis-alignment’ of the suspension. Either one of the front end’s Toe or Camber setting has gone off
  • This could be due to either
    • Alignment knocked out due to impact
    • Suspension bushings have failed allowing the wheels more freedom to drift and go out of alignment
  • Bushing Failure can be checked by using a Pry-bar at each bushing location and trying to move the Lower Control arm.
  • This test is best done at a pit where the wheels are on the ground. 
  • While prying the Control arm, watch the tire and see if it moves easily then it means the bushing has failed.
  • Also look for Cracks and tears in the Rubber of the bushing
  • If found to worn then they must be replaced

Front Shock Absorber Failure

Symptoms:

  • Front end feels Bouncier going over bumps
  • On a rough road it feels as if the front end is losing grip as you increase speed
  • Poor Handling
  • Knocking and squeaking noises from the front

Troubleshooting Front Shock Absorber Failure

  • The Bouncy Ride symptom points to the Shock Absorber as a probable cause.
  • The noises coming from the rear are partly due to the failed shock absorber allowing the bump stops to contact more often. And also the noises partly come from the worn out shock mounting bushes that allow the shock to move and hit against the mounting brackets.
  • If your vehicle has crossed 50K miles, then it could be due for a shock replacement. Due to long-term internal wear, the shock starts becoming ineffective over time.
  • If the rear shock has started leaking oil due to a failed oil-seal, then it means that the shock will no longer be effective.
  • One good way to tell if your shock has failed or not is to do a “Bounce Test”. Put all your weight on one of the front corners of the vehicle pushing it downwards. Keep oscillating the corner till you feel that it has reached its maximum height. Once you take your hands off the corner, observe how it settles. If it takes more than 2 oscillations to settle, that means the damper has failed.

Pro Tip

  • Once the Strut Shock absorber has been dismantled, there is one more way to see the shock condition for yourself by way of a ‘Compression’ test. 
  • You can simply apply force on the top of the shock and compress it. If it can come back up on its own, then the shock is in fairly good condition. But if it takes too long or doesn’t expand on its own, it’s confirmed that the shock absorber has failed.

Bouncy Ride

  • A Bouncy ride is always due to a loss of suspension Damping
  • Damping is provided by the Shock absorbers of the rear suspension. When a Shock absorber has failed, this results in a Bouncy ride

Troubleshooting Bouncy Ride

  • A Bouncy ride quality signifies a failure in the rear shock absorber
  • It could be either due to a Shock absorber oil seal failure, which caused it to leak, OR simply long-term wear and tear
  • Inspect the Rear shocks at the bottom-most portion for signs of oil-stains
  • It seems that the inside wheel was not planted enough on the tarmac to get lateral grip
  • If the Tire is ruled out then the only remaining Root Cause is the Rear Shock absorber. Weak/Leaking Shock Absorbers can cause lateral grip problems.
  • Check the shocks for Ruptured mounts and oil leakage stains on the shock tube
  • Even if there are no oil stains, the shock could have simply worn out over the miles. Typically the shocks would last around 40K miles depending on usage. It is recommended to replace at 50K miles, when you would most likely see deterioration in performance
  • While replacing the shock, make sure to replace the rubber mounts and bump stops as well.

Diving during braking

  • This is a clear symptom of a failed Front Strut Damper
  • When the suspension Damping action has failed, the suspension, under extreme loads, compresses and expands without restriction or control 
  • When the vehicle Brakes, nearly 80% of the vehicle weight gets transferred to the Front Wheels causing the front suspension to compress, causing the vehicle to ‘Dive’. Dampers are designed to control this ‘Dive’ Motion by providing Damping resistance.

Troubleshooting Diving during braking

  • If your vehicle has crossed 50K miles, then it could be due for a shock replacement. Due to long-term internal wear, the shock starts becoming ineffective over time.
  • If the front strut shock has started leaking oil due to a failed oil-seal, then it means that the shock will no longer be effective.
  • One good way to tell if your shock has failed or not is to do a Bounce Test. Put all your weight on one of the front corners of the vehicle pushing it downwards. Keep oscillating the corner till you feel that it has reached its maximum height. Once you take your hands off the corner, observe how it settles. If it takes more than 2 oscillations to settle, that means the damper has failed.

Rear Knocking Sound

  • A knocking sound while driving on normal roads emanating from the rear
  • Sound seems to increase while going over a rough patch

Troubleshooting Rear Knocking Sound

1.Anti-Roll Bar Linkage Failures

  • Rear Knocking sounds that increase on a rough road are the signs that point to an issue with the Anti-roll bar(ARB) links.
  • An Easy way to check the ARB linkages is to go underneath and hold each link and shake it by hand observing for movement or noise at each linkage point.
  • The perfect way would be to remove the ARB Drop Links and check the ball-joint for excess play

2.Rear Shock absorber top mount Bushing

  • The rear Shock mounts have rubber bushings that are tightened against 2 plates
  • If these bushes wear out then it would cause knocking noises in the rear suspension

Front Strut Top Mount Failure

Symptoms for Strut Top Mount failure are:

  • Knocking and Creaking Noise coming from the front while steering in a parking maneuver or when locking the steering
  • Knocking Sound every time the steering wheel changes direction of rotation

Troubleshooting Front Strut Top Mount Failure

  • The Top Strut Mount contains a bearing that allows the strut to rotate while steering
  • When the Top Strut mount is damaged, the bearing also fails and restricts the strut from rotation during steering. This is what causes the knock and creak noises.

Pro Tip

One more reason that the Strut top mount fails is that Shock Absorber might not be working properly; it might not be dampening the road impacts. So when replacing the 

Rear Trailing arm bush failure

Symptoms:

  • The car seems to roll more
  • Poor handling while Lane Changing
  • Uneven Tire Wear pattern
  • Knocking Noises while going over Rough Patches

Root Cause:

  • Due to a Tire wear issue, it can be inferred that the alignment of the rear suspension is outside of the recommended settings. But this is still a symptom.
  • The cause for alignment change points to the Rear suspension Control arm Bushings that may have got worn or damaged

Troubleshooting Rear Trailing Arm Bush Failure

  • The Rear Control Arm bushings wear out over time and crack due to age
  • To assess the bushing condition, you can use a Pry-bar and insert it between the Each of the Rear suspension control arms and the rear Subframe. Now, try to move the Lower Control arm using the Pry-bar and observe the movement at the Bushing location. If the lower control arm moves without much force, then it means that the bushes have worn out.
  • When inspecting the Rear Trailing arm after removal, closely observe the bush for tears and cracks.
  • The Bushing is Press-fitted onto the trailing arm and is a replaceable part
  • The old bushing can be pushed out by burning the rubber in the bush. Once the Rubber melts, the bushing inner and outer race can be easily tapped out.

Pro Tip

  • You can press fit the bushes by simply using a long Threaded Bolt and a collar with inner threads to press against the opposite-side bushing

Conclusion

In this brief article we have discussed the different BMW Z3 Suspension problems, what the causes are, and Troubleshooting Tips.

In case of any questions or comments, please feel free to get in touch.

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