[Archer-s]

Need some advice, I've had M Peformance suspension fitted to my 320d M Sport, and since doing this I am finding the road noise has increased significantly, especially on the motorway. The tyres are the same as before, and on every surface I would say the road noise is much more audible, to the point motorway driving is becoming a pain.

I know many people have ACS which is the same drop and some people are running birds suspension kits, but not seen anyone complain about the noise.

To give an idea, I travel the M4 at least once a week, and before you could hold a conversation with the passengers quite easily, it's now raised voices verging on shouting.

For those of you with experience of lowered/uprated suspension, can you please share your experience? Is this normal?

I have got it booked in, but just wanted to check I am not being OTT about the noise?

PS - the car has also had MP brakes and power at the same time, i will do a full write up once I have this issue sorted

[Tengocity]

I've had ACS springs, and now ACS RS coilovers and never noticed any change in road noise afterwards.

[Archer-s]

Thanks, That's got to be the quickest reply ever, and yours is on the xdrive, so the drop is bigger?

[Tengocity]

Originally Posted by mssond

Thanks, That's got to be the quickest reply ever, and yours is on the xdrive, so the drop is bigger?

The drop is huge, so any change can't be related to the drop in itself.

[Gixerste]

AC springs with standard shocks on a M sport s drive and the noise levels are the same as they were with standard springs

[Colmsport]

Did you have the geometry set after the car was lowered? Just wondering if your tyres are being eaten creating more road noise?

[Archer-s]

Originally Posted by Colmsport

Did you have the geometry set after the car was lowered? Just wondering if your tyres are being eaten creating more road noise?

Geometry was done, but it does sound like this could be plausible

[Archer-s]

For the geometry would it be set the same as a std 320d or is there new settings to complement the new shocks and springs?

[Archer-s]

Bump

[Archer-s]

Can anyone find out what the sport chassis settings in SA 226/704 are? This is what the car should be setup as

[Archer-s]

Looking around it seems this is just the sport 226 and m sport 704 suspension, so settings are the same as before

[snipnoob86]

strange one.... my spring swap is as you say. no difference. but the tyre swap from rft to non rft was magical.

[monkeyninja]

How long have you had the new setup? What do think compared the standard msport suspension? How much did it cost?

[HighlandPete]

Originally Posted by mssond

Need some advice, I've had M Peformance suspension fitted to my 320d M Sport, and since doing this I am finding the road noise has increased significantly, especially on the motorway. The tyres are the same as before, and on every surface I would say the road noise is much more audible, to the point motorway driving is becoming a pain.

I know many people have ACS which is the same drop and some people are running birds suspension kits, but not seen anyone complain about the noise.

To give an idea, I travel the M4 at least once a week, and before you could hold a conversation with the passengers quite easily, it's now raised voices verging on shouting.

For those of you with experience of lowered/uprated suspension, can you please share your experience? Is this normal?

I have got it booked in, but just wanted to check I am not being OTT about the noise?

PS - the car has also had MP brakes and power at the same time, i will do a full write up once I have this issue sorted

The answer is probably very simple, the change in suspension and brake components.

You are running the same tyres and let's suggest the geometry has been set to the same calibrations as the normal M-sport suspension. If so, then there should be no difference in tyre to road contact.

Tyre noise to the interior of the car has two specific transmission routes, air-borne and structure-borne.

The air-borne route is virtually the same, using the original tyres, give a slight change in ride height and wheel position in the body/wheel cavities. Let's assume the suspension geometry is in spec' for an M-sport suspension. Therefore the radiated tyre noise and cabin insulation/sealing to air-borne noise has not been changed in this instance. Air-borne tyre noise should be near identical, pre or post changes.

Structure-borne tyre noise transmission can now be completely different. A new set of working frequencies, with your modified setup. You have a different strut, damper and spring rates. Plus you have changed the brakes, so a completely different unsprung weight. This can translate to a change in vibration frequencies, from the wheel and tyre. Transmit in a completely different and unpleasant frequency range, to the car's body and interior.

[Archer-s]

Had it since December, it sticks to the road much better, much flatter in the corners, it does highlight the lack of feedback from the steering and the noise is becoming an issue on long journeys. Comfort wise, it's actually really good, it is stiffer but not harsh. Cost was circa 1400.

After speaking with birds (didn't find BMW much help with the noise), it's prob the top mounts that supplied with the kit, they look like they might be different, might be a cheap mod for others if someone can confirm the part numbers for the mounts.

My gut feel is non rft is the way forward, will prob be near perfect once added, but with a young family and lots of motorway miles, I really don't want to go non rft. The current ones are Bridgestones, so maybe newer rfts will reduce the noise or I might go back to the original suspension setup.

If anyone is interested in the M Performance Suspension, make me an offer on PM.

[Archer-s]

@highlandpete, think that's spot on, combination of things, the brake size has only changed on the front, from 330 to 370 as I had the m sport brakes before. Hopefully the answer is to sort it at source, ie tyres, but seriously considering going back to std due to the m way miles

Little bit disappointed there isn't a huge amount of support from BMW