[330DW]

Hi All,
Been a member on here for years but not a frequent poster. Moved away from BMW last year but got drawn back in again in the form of an F32 420D M Sport.
One of the things I'm noticing on the 4 series compared to my old F31 3 series is that the ride quality isn't that great and I'm looking for some advice and opinions. I know these topics have been discussed at great length on here but I haven't found that much specifically on the F32.

Currently the car is on standard (I assume) passive suspension, 19" wheels with old Bridgestone runflats on the front and brand new Good Year Eagle F1 Runflats on the rear. The slow speed bumpiness I can live with, the issue is on the motorway it just bounces and bumps over any tiny undulation that you can't even see on the road even on pristine motorway that was smooth in my last car. Pretty sure my F31 330D on 100k miles was not this bad (granted X-drive suspension).

I was wondering for advice on any quick wins or changes to improve it. Ultimately I plan on changing the suspension to ACS sports suspension in the near future and been reading all of the reviews and threads on here, anyone on here with the F32 on ACS springs and dampers that can share their experience?
Has anybody changed from 19" RFT to 18" non-RFT and what is the difference in ride quality with the larger sidewall?

Any advice is much appreciated, thanks!

[g9icy]

I've had ACS springs (not dampers) on my 435d f36 and they made a massive difference, but the thing that made the most difference was getting rid of the run flats.

The most comfortable setup was actually just with Michelin Pilot Sport 4 S* with the stock springs. It felt very smooth and comfortable. The ACS springs made the ride slightly harder, and speed bumps did feel a bit of an "event", but felt better when at speed.

It's worth noting I had adaptive suspension on the 435d, and I believe the 435d specifically had stock springs that are spongier than the other cars in the lineup.

If I were in your position I'd start with better non-rft tyres (not necessarily MPS4S given its a 420d), however the Eagle F1s are pretty good, so maybe the stock springs on that car just aren't up to it, in which case, I can recommend ACS, but as I said, they're better at dealing with bumps without being crashy, but they can be a bit tougher than stock at slow speeds. It's hard to explain. If you want pure waft, then ACS may not be right.

[SteveChester]

Normal tyres and a set of Bilstein dampers with some decent springs would see good results.

[330DW]

Thanks for the advice, I'll start with ditching the RFTs and go from there

[johnung]

Originally Posted by 330DW

Thanks for the advice, I'll start with ditching the RFTs and go from there

You don't say what year or what mileage? About half of the harshness is from stiff runflats. Shorter 19" sidewalls provide less cushion that 18" which are the sweetspot for these cars. If you go 18" and the stock size is 225/45-18 then go wider for better ride such as 235/45-18. Best handling is 245/40-18.

Gotta be careful when you start changing springs and dampers. There's a lot of terrible advice on social media. Avoid Bilstein and H&R if ride quality is a concern. Both are stiff/harsh.

Your worn dampers are more to blame than stock springs. Koni Special Actives are a great choice ride both quality ride and handling. Make sure to change out old rubber bits like spring perches to get back new ride feel. If you do change springs do something mild like Eibach. And install shorter bump stops from the F80.

Hope this helps!

[Alpina 91]

Agree with previous messages . Remove run flats and fit PS4s.
My Alpina D4 superb ride in comfort .

[330DW]

Thanks for that, I will seriously consider any suspension mods before going ahead to make sure it will be what I want from the car. My car is a 2017 currently around 37k miles.
I've got the rear PS4S tyres from my old car in the garage so will replace the fronts for new and swap them on the rear and see how it improves.

[Lorcan]

F3X RWD M Sport suspension is, for want of a better word, crude. There is no need to drop down to 18s though. Our F32 328i Lux demo was perfectly comfortable on springs and 20s.

Bin the runflats, fit AC Schnitzer sports suspension and you'll be a happy bunny.

[Lorcan]

FWIW we'll have a G22 RWD on sports suspension available for test drives shortly.

[330DW]

Originally Posted by Lorcan

F3X RWD M Sport suspension is, for want of a better word, crude. There is no need to drop down to 18s though. Our F32 328i Lux demo was perfectly comfortable on springs and 20s.

Bin the runflats, fit AC Schnitzer sports suspension and you'll be a happy bunny.

Thanks for the details Lorcan, It's much appreciated to see photos of an F32 on ACS suspension, there aren't many to be found easily on here.

Just got to do a bit of saving and I will pull the trigger. Got it booked in to change the tyres this weekend.

Keep me up to date about the G22 and if its near me (north west) I might come and check it out

[cfm56d7b]

Originally Posted by 330DW

Thanks for the details Lorcan, It's much appreciated to see photos of an F32 on ACS suspension, there aren't many to be found easily on here.

Just got to do a bit of saving and I will pull the trigger. Got it booked in to change the tyres this weekend.

Keep me up to date about the G22 and if its near me (north west) I might come and check it out

Joining this discussion a bit late. bm330dw, is there a way for you to provide more details about your suspension behavior improvement goals?

- Comfort (as a function of suspension travel and rebound / compression cycles)
- The opposite of comfort; less body roll, less float
- Harshness; non RFT tires will help as suggested earlier

[330DW]

Originally Posted by cfm56d7b

Joining this discussion a bit late. bm330dw, is there a way for you to provide more details about your suspension behavior improvement goals?

- Comfort (as a function of suspension travel and rebound / compression cycles)
- The opposite of comfort; less body roll, less float
- Harshness; non RFT tires will help as suggested earlier

Yes, of course. My goals are to improve the ride comfort at motorway speeds mainly. I am not hugely technical on suspension behaviours so I'll try to explain in my layperson terms.

It does feel quite harsh and transfers bumpiness from the overall undulations of the road. For example if trying to sip a drink and you have to have several attempts because of the bumping. I hope this gives a visual!

I can handle the feeling when you go over things such as cracks in the road or "cats eyes", that just comes with the sportier road feel of a bmw in my opinion.