[SEF]

Hi,
I can only compare to my previous lci e60 535d but my lci f31 335d is seriously lacking when it comes to high speed stability.
On a private road at 100-130 ish the 335d was rather unnerving where the 535d would have been rock solid all the way to the limiter and beyond.

The car is a 16 plate running adaptive suspension with almost new RFT Bridgestones with pressures as per the door card and was in sport+ setting.
I am considering getting the AC Schnitzer springs anyway and hope they might help?
The car just felt rather twitchy and I would did not feel confident to hold it at 120+ for more than a few seconds, was on a straight smooth section of road.
Anybody else have any views or similar experiences?

[....,,,,..,,..]

Considering you would never do over 100 in the UK, it's not an issue.

Doing over 100mph in the UK = complete cock.

[SEF]

Fair enough but this is an issue that is apparent at 60 upwards and multiplies at higher speeds. Maybe my previous car was exceptionally stable but this one seems to need constant tiny adjustments.

[Spacer]

I've had 153mph out of my 330D on an autobahn, and it felt solid as a rock. I cruised for an hour or so at 120mph, with no issues.

[....,,,,..,,..]

Ditto had my xdrive without ACS upto a fair speed and regularly drive Welsh roads without any real issue.

The big issue on xdrive is more noticeable on bends etc,

However, if you are having issues on a smooth section of road in a straight line, it sounds more like wheel balance than anything else.

Have you hit any pot holes?

Yes fit ACS setup and MPSS, however I would look at wheel balance, tracking first.

[ar68]

Originally Posted by SEF

Hi,
I can only compare to my previous lci e60 535d but my lci f31 335d is seriously lacking when it comes to high speed stability.
On a private road at 100-130 ish the 335d was rather unnerving where the 535d would have been rock solid all the way to the limiter and beyond.

The car is a 16 plate running adaptive suspension with almost new RFT Bridgestones with pressures as per the door card and was in sport+ setting.
I am considering getting the AC Schnitzer springs anyway and hope they might help?
The car just felt rather twitchy and I would did not feel confident to hold it at 120+ for more than a few seconds, was on a straight smooth section of road.
Anybody else have any views or similar experiences?

I am finding my car exactly the same. Its not a pleasure to drive at speed so I have ordered some ACS springs to see if they improve the situation, should be fitted this week. Will keep you posted.

[Drek]

Originally Posted by Brigand

Considering you would never do over 100 in the UK, it's not an issue.

Doing over 100mph in the UK = complete cock.

I did 125 last week and I was in the UK.

[DarCol]

Try dropping the tyre pressures a little.

I've recently inflated mine as per the door card as it was .2 - .3 bar below the recommend pressures originally and was noticeably more skittish.

Dropped them a little and it felt completely different.

[DarCol]

[QUOTE=Drek;20278114]I did 125 last week and I was in the UK.

Brigand will now regard you as a 'Complete Cock'

LOL

[rich100]

it's ok the list is long and distinguished.

[teaston]

Mine is same as yours but an F30 and it also was very floaty at high speed! ACS springs had completely fixed it as far as I can tell, even in comfort mode.

[Ross_T_Boss]

I set my speed warning at 100mph. I shall call it my cock chime.

What are the preferred tyre pressures whilst at speed?

I tend to find mine are a bit 'squidgy' at 2.5-2.6 bar all round on MPSS but stable for fast cruising. I found it a bit unstable last week and measured 0.2bar less on one front, evened it up and it feels well balanced again. The TPI said it was 0.1bar less. Perhaps worth checking?

On stock suspension I wasn't happy at all in triple digits. Sport mode helped alot but any quick reaction just felt unstable. Springs made a huge difference - and Bilstein's even more so. If I was going to put a measure on 'confidence with speed' I'd say 90 Stock/Sport = 110 ACS/Sport = 130 Birds B3x.

[Lorcan]

AC Schnitzer springs will make it feel more planted but the constant small corrections usually mean wheel alignment is out. BMW have fairly wide tolerances on alignment, a good specialist can dial them in properly and make a big improvement here.

[Watsey]

Springs, ARBs and MPSS have made a massive difference to my car, even with it having MSport suspension to start with - cornering, high speed stability (pitch and resistance to side winds). It's rock solid at the speeds you mention.

A I'm sure you know, 335 D X-Drive has SE suspension so high speed running may not inspire confidence. Which aspects do you want to improve ?

[SEF]

Thanks for all of the replies so far.
I just want the car to be stable at all speeds and not fidgety and floaty as it is now.
I'm sure from the advice on here the springs will to a large degree along with correct alignment cure the issues.
I had hoped I wouldn't need to change anything as i had read the LCI is improved but it's clearly still some way off my expectations
I had MPSS on the 535d and they were fantastic so will eventually change over when I need new tyres but that will take a year or two.

[pienchips]

I felt the same here, at cock plus speeds the car felt "floaty" for want of a better word, not at all confidence inspiring. I'm now running on Eibach springs with none adaptive suspension and MPSS shod 18"s and whilst its still not the last word in handling, its an order of magnitude better than it was.

[XK140]

My opinion,just subjective,so if I'm wrong it's OK.
My car was bought second hand and although it's an M Sport I found that it had the standard softer suspension.
There is a curve on our local by pass that I have used to judge and compare the stability of various cars and the BMW at 70 on this curve doesn't feel dangerous but does not feel great,a bit too floaty.
I will also say that the previous car,a 10 year old IS 250 felt better on this curve.
Any sports car with stiff suspension,e.g. a 350Z a had a few years ago was rock solid on here.
I believe when you have this issue with cars the best remedy is to uprated the shocks ( dampers,to give them the correct name) .Stiffer springs help and a lot cheaper than replacing the shocks,but I believe the root of the problem is under-damping.
Why are some Bm's like this?Just a guess, but probably because the dampers are over soft to compensate for the hard edge given to the ride by the RF tyres.

[Tengocity]

I did 163mph (HUD reading) on the autobahn and it felt pretty good. That was just ACS springs.

Doing similar now feels with ACS RS suspension it feels awesome!

[Buster Blue]

Originally Posted by rich100

it's ok the list is long and distinguished.

For those that know "Goose"

[John435D]

My 435d had this issue which was made much worse in a headwind, the acs springs helped a lot but it still wasn't perfect, switching to continentals from bridgestone helped, also had the alignment done at a specialist porsche centre which helped again.

I still put the adaptive in sport mode though doing 80ish, it seems much better and very planted.

[mikeoz]

Iv had my 330D bouncing on the limiter back in June and cruised at 120 to 130 for long periods of time on the A8 going form berchtesgaden to Landau which was a 5hr drive.
Light traffic and the car felt totally planted. Have ACS springs but went to Germany before I had them also and no issues. Having worked there for 20 yrs I'm pretty use to the roads but had total high speed confidence in the car.

[teaston]

Originally Posted by Lorcan

AC Schnitzer springs will make it feel more planted but the constant small corrections usually mean wheel alignment is out. BMW have fairly wide tolerances on alignment, a good specialist can dial them in properly and make a big improvement here.

I think the small corrections are more likely to be tramlining from the run craps isn't it?