[cherrybeemer]

I recently purchased the new 2009 facelifted 320d m sport - a beautiful car that handles wonderfully - though i find that when going at high speed the car seems to be slightly unstable and the back end sort of wobbles from left to right - as i say it is the m sport model so it has the diffuser and its on 18 inch m sport alloys with the hard run flats! Any ideas as to whether this is normal or is there something not quite right here?! Thanks

[Staszek]

Originally Posted by cherrybeemer

I recently purchased the new 2009 facelifted 320d m sport - a beautiful car that handles wonderfully - though i find that when going at high speed the car seems to be slightly unstable and the back end sort of wobbles from left to right - as i say it is the m sport model so it has the diffuser and its on 18 inch m sport alloys with the hard run flats! Any ideas as to whether this is normal or is there something not quite right here?! Thanks

On smooth or rough roads? On smooth roads the car should be a rock and very stable, on rough roads with the larger 18" wider wheels and RFT's the car tends to tramline a ton, but usually you dont only feel that in the rear.

Is the bacck end swaying?

[cherrybeemer]

Smooth motorways, by high speed I mean 100mph+ and swaying definatley is a better word come to think of it, its def not tramlining as that happens at the front, thanks

[cherrybeemer]

the car is only 5 months old and only done 3400 miles so i doubt its uneven tyre wear but it could be the wheel balance or alignment, must look into those - thanks

[stressdoc]

Something is not right. My E90 seems to only get more and more planted at speed. I would suspect tires.

[6speedGaren]

May be it was a windy day or something I go 100+ with no problems on open roads when no one around

Edited: Btw, if it was an alignment you would have felt it at about 55mph or so no?

[Staszek]

Originally Posted by cherrybeemer

Smooth motorways, by high speed I mean 100mph+ and swaying definatley is a better word come to think of it, its def not tramlining as that happens at the front, thanks

Yea I would check wheel balance and alignment.

[E92 LeMans]

Mine is fine been up to 150 mph The is deff some thing wrong

have you checked tire pressure ?

I am running 18 MV3 on M sport

[one.miguel]

+1 on the tire pressure. I've seen new cars with weird tire pressures coming from the dealer.

[cstavaru]

I have 2009 335i M Sport and there is no difference in drivetrain/suspension other than a slightly wider rear track for 335i. And there is no swaying. Looks like tire pressure, if it was alignment you would feel a vibration in the steering wheel. The pressure must be 2.5 atm/front and 3atm/rear. Check it.

[Tallest]

i definately know what you talking about... 320d here. but i noticed this on the winter tyres so i suspect it is tyre thing. at around 140mph on highway and on michelin pilot sport summer tyres the car felt rock solid and even more planted at higher speed. Has to be the tyres, alignment, etc.

[AlanQS]

OP: try posting in the U.K. forum as there are a lot more people with 320d who can give you their direct opinion.

Having said that, you've had sound advice and suggestions here.