Today I have a Holden Astra with a suspension knock noise. The front suspension strut tops have collapsed which is causing the noise.
I removed and replaced these with new units, quiet and easy job with the correct tools. Not a job to ever try without a quality spring compressor as there is a lot of stored energy in the springs.
You can see clearly in the photos attached the difference in height between the old and new strut tops. Also in the 2nd pic cracking is visible around the centre bolt hole. Lucky these were replaced before a completed failure occurred.
Once the strut tops are replaced the vehicle requires a wheel alignment. Then its back to quiet ‘knock’ free driving.