BMW ZM

[Juanmania]

I’m posting this to help anyone chasing a similar front-end noise, because this took me almost a year to narrow down. Car is a BMW Z4 G29 M40i (2021). After multiple inspections and parts checks, BMW currently suspects the electric steering rack (EPS), part number 32105B653B1 and is getting replaced in less than 2 weeks.

MAIN SYMPTOMS

• Noise only appears once the car is warm (after ~30–40 minutes of driving).
• Happens at low speed (10–20 km/h), especially over uneven surfaces or when weight transfers side to side.
• Starts as small knocks and becomes more of a rubber/creaking sound when fully warm.
• Hard to localize to left or right – sounds central, under or behind the engine area.
• Steering angle doesn’t matter much; often happens with wheels straight.
• Can be felt slightly through the chassis or steering wheel.
• Suspension visually checked, sway bar replaced, nothing obvious found.

REPRODUCTION METHODS (WITH VIDEO EXAMPLES)

1. Going Slow
   
   Driving slowly in an underground car park makes the noise very noticeable. Smooth concrete and small body movements seem to trigger it consistently.
2. Small Steering Inputs
   
   Very small, fast steering wheel movements reproduce the sound. With the car ON it sounds more loaded/creaky. With the car OFF it can still happen but requires more force and sounds slightly more hollow.
3. Bouncing the Car
   
   Pressing down on the front of the car when warm can recreate the same creak/knock, suggesting it reacts to chassis load rather than just steering angle.

WHAT HAS BEEN CHECKED / RULED OUT

• Control arms and bushings inspected.
• Silentblocks lubricated.
• Sway bar and bushings replaced.
• Underbody panels checked.
• No accident history or visible structural damage.

CURRENT BMW DIAGNOSIS

BMW suspects the EPS steering gear itself.


They plan to replace the full steering rack assembly:
Part Number: 32105B653B1

I’ll update this once the repair is done so others can compare symptoms if they run into the same issue.

 

[Wolter]

Hi, had some strange noise coming from front left strut/wheel linkages as well.
Had a couple of inspections done…nothing to be found.
Had to bring car in for regular check in and finally found damaged rubber piston cover. Cause was left in place transportation blocks…would say this should have been noticeable for me (and previous owner) when driving…which was not the case (thats probably me). Anyways, see pictures included.
After driving for quiet some road with these blocks not only the piston rubber is damaged, but also the wishbone needs to be replaced due to wear.