01-21-2024, 08:01 AM | #1 |
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BMW M5 F90 strange sound and knocking in the rear of the car when passing speed bumps
Hi all👋help me solve the problem
BMW M5 F90 Competition 2021 When passing speed bumps in the rear of the car, a loud sound is generated, accompanied by a kickback on the body. It feels like a loose object that, when driving over an uneven surface in the compression/distension phase of the suspension, jumps up and drops sharply. It does not depend on the ambient temperature, vehicle loading, luggage compartment, fuel tank fullness or other factors. It appears consistently from the moment I started using the vehicle. If I pass a speed bump quickly or, conversely, too slowly, the sound does not appear. When driving in the usual mode, accentuated subsidence and return of the rear axle always appears. It doesn't feel like a suspension problem, but like a loose object in the car. We have been dealing with this problem at the official dealer for two months now, but we cannot find the cause. ⁃ The luggage compartment of the car, the rear shelf, and the rear seat were completely disassembled ⁃ They took off the bumper ⁃ Complete chassis diagnostics ⁃ A speed bump was installed in the workshop. The sound appears, but its localization cannot be determined from the outside ⁃ The technicians rode in the trunk, in the rear cabin without a seat, the unit is also not clear ⁃ Checked the brake pads ⁃ Just in case, we changed the rear shock absorbers ⁃ Replaced the fuel tank according to TIS BMW with reinstallation of many components, including the exhaust route all this did not lead to results. and, most importantly, I drove other m5 f90 competition and they also have this effect. what is this?)) please tell me, share your experience. Thanks🤝 |
01-21-2024, 12:21 PM | #2 |
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Mine does this, too. I notice it most in my neighborhood when in hit some small uneven areas/transitions at speeds around 25-35mph. I don’t hear it as much at lower or higher speeds on other roads. Indiana roads aren’t great, and some in my neighborhood are a little worse for wear. However, I have a Dinan HAS on mine, so I just figured it was tapping the bump stops, even though I have it lowered as little as possible. I’ve checked things like making sure the battery is locked down tight. I just deal with it now.
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2021 M5 Competition
Donington Grey, Black Full Merino Leather with Dark Carbon Trim, B&W, Exec, DAP 21" Vossen HF-5s. M Performance Carbon Front Splitter, Side Grilles, and Rear Spoiler Pro. Mode Carbon Trophy Rear Diffuser, Acexxon Honeycomb Rear Reflector Inserts, and IND Painted Front Reflectors. |
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01-21-2024, 01:37 PM | #3 | |
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01-22-2024, 10:49 PM | #5 |
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Can it be a derby or a piece of a rock somewhere in a rocker panel or on top of a fuel tank or inside of a subframe tube?
Or on top of a plastic undercarriage covers
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01-23-2024, 12:20 AM | #6 |
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no, of course we checked such moments immediately. Everything was taken apart and looked at. it's something in the body of the car
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01-23-2024, 01:16 AM | #7 | |
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Another guess would be faulty strut.
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