Golf Mk7 Cabin Noise and how to greatly reduce it

Since owning the 2018 MK7.5 GTI for almost 2-years I have no problems at all from shock absorbers since changing to the Koni Actives, but I did have an intrusive hollow, booming whining noise within the cabin, not quite the same as I witnessed in the 1.5TSI but it was there and was very annoying. Even on smooth surfaces it was irritating. Changing from different surfaces would bring about a booming resonance, really loud at times. What had VW done to these face lifted models? Scrimped on sound deadening I believe. Should a 30K car sound like this - I think not.

My first step was to insulate all 4 wheel-arches from underneath the car. I then fitted sound deadening under the rear seat, over the rear wheel arches and in the wheel-well, where bare metal could be seen. Under the boot boot floor I fitted a foam type insulation and that I also fitted under the parcel shelf. Whether the foam helped I have no idea but its done.

Having completed long runs from UK to Spain & southern Portugal I was tired of this sound and was at the point of changing the car, swearing never to have another VW, but then I was contacted by a member of the VW Golf MK7 Forum late 2019. This gentleman from Scotland goes under the name of GolfDave on the forum. He wrote to me and gave details of a rear sub-frame harmonic damper originally designed for the MK5 Golf as all MK5/MK6/MK7 rear multilink subframes (& all other VAG group cars that use it) have those same two pre-drilled holes in the subframe to take the part.The damper is currently fitted to the current Audi A3 "saloon",but is not fitted to the A3 hatch or other A3 versions. He told me this would reduce cabin noise as it reduces the resonance from the subframe. I was very sceptical on whether this little device weighing 1.8kgs would do anything at all and would simply be a waste of time & money, but the more I read, the more I was keen to try it.

The cost was about £60 and the part can be sourced from Audi Dealers.

On my return to the UK in March I had this harmonic damper fitted but due to covid I rarely used the car, but I could detect a change in cabin noise. However, once we were able to travel distances, where I would drive over different road surfaces, motorways, A roads etc I then could not believe the difference in sound levels. Gone was the booming resonance sound over coarse surfaces. I could hold a conversation at high speed. I was not irritated by the hollow whining any longer.The difference was remarkable as the cabin became very quiet. It will never be silent of coarse but the whole tone has changed. On good surfaces it is very quiet and on super-smooth tarmac its unbelievable. The car is now so relaxing to drive. I am so grateful to GolfDave as I no longer have any desire to change this car.

If you do nothing else to your car then just fit this damper. Here is how its fitted.You can do it yourself or as I did I asked a local Audi specialist to do it and the cost was £25 and it took about 15 minutes to fit. Any service shop would fit it if you cant do it yourself.

Parts list & approx. costs in UK £
Item No.6:- 1K0 505 563, Balance weight, £58.65 (x1)
Item No.7:- N 901 838 03, Hex collar nut self-locking M8 (A03G), £0.81 (x2 quantity)

Why did VW not fit this device - as GolfDave has said - VW just wanted to save pennies plus saving 1.8kgs in weight might have increased fuel economy by minuscule percentage that none of us would be bothered about.

This is short video I made relating to this part.

If anyone fits this balancing damper and they feel it has been a benefit then please let me know by email.