[Orangemad]

Thank you for completing the survey . I will be sharing finding on here this weekend and with my local workshop when my car visits again next week and I will be contacting BMW UK Customer Services and sharing the findings with them and Graeme Grieve BMW UK Managing Director. I will post my responses on here.

Cheers

[pmgoliv]

Originally Posted by Orangemad

Thank you for completing the survey . I will be sharing finding on here this weekend and with my local workshop when my car visits again next week and I will be contacting BMW UK Customer Services and sharing the findings with them and Graeme Grieve BMW UK Managing Director. I will post my responses on here.

Cheers

How many answers did you get? I also answered the survey.

[Froggypimp]

#metoo :-)

[Orangemad]

Hello

Please find results from Survey here https://drive.google.com/file/d/1ljL...ew?usp=sharing

Thank you

[pmgoliv]

Interesting... the most common element is M Sport brakes. With the exception of one case, all other have it. Adaptive suspension is not a common element...

Could it be the protection plates generating vibration through the suspension? Or some weird flow of air?

[DConceicao]

I've been running more now and I can hear an excessive road noise, and I think it's worse now than in the beginning (currently with 3.400km)

There are three things that happen for me:

• I can only hear it from 40kph+ below that its not noticeable
• On very flat / new road the sound is much less (there is an incredibly smooth road next to my house and the sound almost disappears)
• The sound changes a bit with speed (although not a lot)

[Yossi123]

Originally Posted by pmgoliv

Interesting... the most common element is M Sport brakes. With the exception of one case, all other have it. Adaptive suspension is not a common element...

Could it be the protection plates generating vibration through the suspension? Or some weird flow of air?

We were discussing the brakes theory very extensively some time ago (check from page 8 of this thread), and if I remember correctly someone here even had the M Sport brakes replaced with standard ones. No change to the sound unfortunately.
Also, the M340 is affected as well, and I believe it has different (bigger) brakes?

Originally Posted by DConceicao

I've been running more now and I can hear an excessive road noise, and I think it's worse now than in the beginning (currently with 3.400km)

There are three things that happen for me:

I can only hear it from 40kph+ below that its not noticeable
On very flat / new road the sound is much less (there is an incredibly smooth road next to my house and the sound almost disappears)
The sound changes a bit with speed (although not a lot)

This is EXACTLY the issue we all have here. Welcome to the support group Interesting that you are another person for who the issue started only after some mileage.

[HighlandPete]

Originally Posted by DConceicao

I've been running more now and I can hear an excessive road noise, and I think it's worse now than in the beginning (currently with 3.400km)

There are three things that happen for me:

• I can only hear it from 40kph+ below that its not noticeable
• On very flat / new road the sound is much less (there is an incredibly smooth road next to my house and the sound almost disappears)
• The sound changes a bit with speed (although not a lot)

To me, on a trouble shooting path, "the almost disappears" situation, almost certainly eliminates any mechanical component requiring changing.

It does appear to be road surface induced. Whether this sets up some vibration, or is simply amplified into the cabin, that is what has to be identified.

Without reading through the topic again, has anyone had a dealer remove the front disc backing plates? Tried running without? There is the possibility that they are involved, as has been mentioned before.

The other point I'm picking up, some only have this problem after a period of time. This fact still points at tyre noise being involved. As tyres wear, they can change the sound they generate.

We have to ask what influence can part worn tyres and/or road surfaces (most likely as a sound generator) have on the intensity of a vibration and/or noise that reaches into the cabin?

[McKrill]

Good news Glaede!

I bought my car with 19" wheels but do not think I have the vibration dampers mounted...

Where exactly are they located?

Could you post a picture?

Did you have other summer tires mounted before? Runflat?

If new summer tires to cure the problem, did BMW pay for it?

[Yossi123]

Did I miss something?

[McKrill]

Glaede wrote, just before my post, that after mounting 20" non-RFT tires and having vibration dampers installed, the noise is gone.

But now his post is gone...

Glaede? Is the noise back, or?

[N.I BMW Owner]

I too have a road rumbling 320d M Sport G20 2WD, manufactured June 2019 with an ‘F’ at the start of the last 7 digits of the VIN/Chassis No.

This is our 5th BMW 3 series, and never would have suspected such a serious design problem.

We only took a very short test drive at low speeds and the sales guy was talking a lot, so we never noticed anything until we had the car home.

We took the car back after two days as they were not open to do so quicker, and asked for a refund, as we had then discovered online that many people everywhere/elsewhere were experiencing the same road/tyre noise problem.

They refused a refund and said we could leave the car for investigation as they admitted/agreed that the noises were obvious when we took the sales man out on a main road, however once the sales manager got wind of our complaint, he insisted that ‘it’s probably just a natural characteristic of the car’!
Meaning that they knew about the issue, got the car sold to us and now we can just keep it as it’s now Registered and there’s probably nothing dangerous about it.

I’m actually a mechanic by trade and have good knowledge of the industry, but broke my own rule of never buying the first year of any new vehicle design, to my peril!

Anyway, as I was getting no positivity at the selling BMW dealer other than they offered to get a mechanic drive the car about after hours, to their home etc., I decided that I’d nothing to lose by investigating the fault initially myself.

Our previous car was Road quiet and had Good Year RF tyres, so we changed the front tyres to Good Year Eagle F1 Assymetric 3 RF, as they have a lower DB rating. This didn’t help a lot, but had some minor influence.

The car had only 3k on it and had probably been lying around due to lockdown, so there was some corrosion minor on the brake disk edges. When the car was lifted off the ground and the wheel rotated there was a grinding noise, so we decided to order genuine BMW discs and pads and fit them. This resolved the scraping noise, but a on test run, the road rumbling was still there!

However, when I had the brake discs off, the hub carriers and the bearing/hub assemblies were exposed. It all looked very inferior in comparison to the rather robust looking M Upgraded Brakes and the upgraded adjustable shock absorbers.

Also the Front Hub carriers are made from an Alloy Aluminium which may be one of the main sources of the rumbling.
There’s always going to be road to tyre noise where rubber meets the road, but if the suspension is acting like a magnifying device, then the noise will amplify and Could be noticeable inside the car.

The front hub and bearing assemblies are also very inferior looking for the size and performance of the vehicle, especially in comparison to the appearance of the brake assembly. The front wheel hub/bearing assembly is a preassembled component meaning that it cannot be recalibrated/checked for tightness, or dismantled. It bolts to the hub carrier, so is easy to change, if required.

The X drive variant of this car has different front wheel bearing assemblies to allow for a front drive shaft. The effect of adding front drive shafts, will add weight to the front hubs, which will act naturally as a resonance damper, so the rumbling may not be just as noticeable on X drive vehicles.

The brake disc backing plates are also quite large, flimsy and ultimately are acting like amplifier devices for undesirable noise. The shape of the disc backing plates also invites small stones to be caught between the disc and the shield. I’ve already had to remove the road wheel to dislodge a trapped scraping stone!

In a further attempt to reduce the road noise, we cleaned the inside of the braking plates and added alloy wheel balancing weights, which changed the natural frequency of them, reducing the tendency of the plates to amplify road noises. However, this too didn’t solve the general rumbling issue.

The body shell also may be part of the problem, as it features Aluminium inner wing panels and as BMW boasts a 20kg weight saving over the F30 predecessor, the vehicle, many areas look thinner and lighter/cheaper.

I suspect that BMW will not wish to admit to design faults, as this would have large financial implications to rectify, and it’s unlikely that components would become unsafe even though there’s no customer satisfaction.

However, if there is a confirmed solution, which involves several components being changed to eliminate the issue I would be keen to hear about it.

The car performs Very well in almost every other way, so it’s a shame if this rumbling road noise cannot be resolved.

[N.I BMW Owner]

Some drivers have stated that Anti-vibration parts were fitted by BMW...?

If so, there will be a permanent warranty/service history and an available invoice to support this work, since BMW would be responsible for paying the charges - please see an example Warranty Invoice attached.

If possible, please ask your dealer for a copy, if you don’t already have the same and post the doc, So everyone here concerned with this issue can see what was fitted or replaced under warranty.

Thanks.

[Yossi123]

C'mon guys, first some breaking news from Glaede and now silence? What is going on?

I am also very interested in the part fitted, as my dealer insists that no solution is available at the moment. Not much hope but I'd like to try it anyway.

[AdamT]

It appears this issue isn’t limited to the estate version?

I can confirm I have a g20, with adaptive suspension and m-sport brakes, 19” Bridgestone run flats, and no issue whatsoever.

[clausmoll]

Originally Posted by Yossi123

C'mon guys, first some breaking news from Glaede and now silence? What is going on?

I am also very interested in the part fitted, as my dealer insists that no solution is available at the moment. Not much hope but I'd like to try it anyway.

Originally Posted by Yossi123

C'mon guys, first some breaking news from Glaede and now silence? What is going on?

I am also very interested in the part fitted, as my dealer insists that no solution is available at the moment. Not much hope but I'd like to try it anyway.

The news Glaede presented isn't breaking. The VR fittings, along with non-rft didn't help me at all. There is no solution to the problem and BMW does not care about you or anyone else with this issue. This will be my last BMW.

[N.I BMW Owner]

I have conducted some further tests and comparisons to F30 3 series and the G30 5 series...

The critical fault in our G20 cars is to do with the Strut Bracing which has been inadequately designed/engineered.

The 1 x part installed on the G20 is a ‘pressed’ plate, probably made of a high tensile steel alloy..., when pressed to form the part, this has generated tensile strength, but has the adverse affect of tension within the part when fitted/installed. Since the part is mounted directly to the inner wing part, any noise generated from the road is amplified by the strut brace and transfers directly to the passenger compartment - That’s the horrible noise we are hearing!

I removed the brace and the noise is almost completely gone.

BMW design engineers should have copied the bracing in the G30 5 series car, then this wouldn’t have occurred. (Please see the diagrams attached)

I am going to re-engineer a modified strut brace in the next 7-10 days, and will let you know.

Additionally, the F30 3 series has extra anti-vibration washers fitted if the car is to run on run flat or winter tires to reduce road noise. These washers may need fitted to our G20 cars in addition to a newly designed strut brace.

I will post again once everything’s completed.

[pmgoliv]

Impressive work. Not to the reach of most (if not all) of us here.

When you say it almost completely gone, do you mean the noise on board in general? Of course some road noise will always be there, depending on road surface and tires.

But I suspect that part is similar to all variants. If so, why it affects only (or more) M Sport ones? And why it affects more Touring models than sedan?

Is this part difficult to access and remove/install? Can this be a problem for BMW resolve the issue?
How could this issue be brought to the attention of BMW AG?

Thanks,

[HighlandPete]

Originally Posted by pmgoliv

Impressive work. Not to the reach of most (if not all) of us here.

When you say it almost completely gone, do you mean the noise on board in general? Of course some road noise will always be there, depending on road surface and tires.

But I suspect that part is similar to all variants. If so, why it affects only (or more) M Sport ones? And why it affects more Touring models than sedan?

Is this part difficult to access and remove/install? Can this be a problem for BMW resolve the issue?
How could this issue be brought to the attention of BMW AG?

Thanks,

Agree, definitely impressive investigation by N.I BMW Owner.

I'm wondering if the noise amplification is influenced by the build combinations and the fact the touring body may have different loadings/stresses across related components.

The other thought in my mind, can the OEM brace be damped in some way? Like wrapping with some sort of acoustic influencing material. May limit the pathway, reduce the intensity.

Will be very interesting to see pictures of N.I BMW Owner's modified part, and read the outcome of experimenting.

[N.I BMW Owner]

The bracing part on the G20 is the only vehicle in the entire BMW range EVER that has a 1 piece constructed part, and it’s also a Flat pressed part. I presume that It would therefor need to be made of a high strength material to function as a long term structurally functional component, especially if the vehicle was involved in a collision. It is well known that ‘mass’ reduces resonance, or indeed softer materials e.g. lead would have a much lower natural frequency to that of a
HSS (high strength steel).

After my last post I decided to check all models to confirm that no other models use a similar strut bracing. The new model 8 series is the only car that initially looks close, but when we zoom in, it’s made from three separate parts, which would reduce the chances of resonance amplification.

So, All other BMW vehicles up to the 3 series G20 (inc. F30, E90, E46, G30, etc...) all utilise tubular pipe/bars, which will have a totally different/lower tone acoustic dynamic to single skin pressed plates.

I don’t know why they’ve decided now to change this age old design, since there’s no real weight saving advantage, and these braces are normally hidden by covering trims anyway.

I did however mention earlier the possibility that the hub bearings may have an influence on these cars too.

We stripped the brake discs off again to further examine the hubs, and although there’s no apparent tolerance in the axis there appears to be something strange when the bearing is rotated quickly in opposing directions..., both sides appear to be similar in function meaning they are from my experience just not smooth enough.

We’ve ordered 2x SKF hubs which should arrive this week, as there’s little point ordering from BMW if they are supplying from the same manufacturer as already used during construction.

Once we’ve modified the strut brace, fitted the front wheel hub bearings and fitted the F30 Damping washers (as shown by part ‘20’ on the previous post part diagram), then we’ll see if the majority of the noise is gone.

There’s always going to be some road noise on rough terrain, but if we can make our cars as good as the F30 that we moved from, then I’ll be very pleased.

So, if this all works, it’s a troubleshooting job for me at BMW

[Yossi123]

Impressive work, really. I am keeping my fingers crossed for you and hope you will resolve the issue, but at the same time I highly doubt that we will be able to propagate all of this work to the BMW and have it officially accepted and implemented...

[HighlandPete]

Originally Posted by N.I BMW Owner

Once we’ve modified the strut brace, fitted the front wheel hub bearings and fitted the F30 Damping washers (as shown by part ‘20’ on the previous post part diagram), then we’ll see if the majority of the noise is gone.

There’s always going to be some road noise on rough terrain, but if we can make our cars as good as the F30 that we moved from, then I’ll be very pleased.

So, if this all works, it’s a troubleshooting job for me at BMW

Good work!

Have you noticed the other topic on general cabin noise, F31 vs. G20/21?

Oksana's post yesterday, (post #12) is an interesting one. Testing M340i xDrive vs. a couple of RWD models.

https://g20.bimmerpost.com/forums/sh...4&postcount=12

I've commented on the possibility of xDrive (drive shafts into the drivetrain mass) helping reduce/damp the sound transmission.

Full topic.

https://g20.bimmerpost.com/forums/sh....php?t=1753502