F10 unstable at 160km/h and above

[rubes72]

Hi, I was on the highway the other day and was wanted to over take a long line of cars. So I excelerrated fo overtale. Upon reaching the speed of 160km/h the car starts to sway. When it reaches 180, it is immpossible to keep it in a straight line. It feels like the back wheels has come loose. I thought it may be the intergral active steering at the back malfunctioning.

When i switch to traction mode, the problem goes away. I can bring her to 190km/h without a problem.

Has anybody experienced this before please. She should allow me to stay straight at any speeds.

No tire wobble or vibration. It feels like mini fishtailing.

 

[canuck78]

You drove 160kph with the traction control off on a rear wheel drive???

You are lucky to be here with just mini fish tailing


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[moots]

You drove 160kph with the traction control off on a rear wheel drive???

You are lucky to be here with just mini fish tailing

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Why?I have driven my previous e28,e34,e39 without traction control in excess of 200km/h with no issues.And I am still driving my
e60,also without traction control ,also in excess of 200km/h with nil issues.Must the F10 traction control be switched ON to
be able to be driven at a "mild" 160km/h?

 

[astroboy]

Yup.. you shouldn't need traction control to keep the car going straight. Go to a reputable alignment shop and check your alignment. My guess is your rear not enough toe-in.

 

[rubes72]

That is the problem, i did the alignment but could not find any problems. All within spec. The thing is if it is an alignment issue, turning iff dsc will make the problem more pronounced, but does not, which leads me to believe that it could be somewhere else. Nobody had has this problem before? I have been checking other forums, and some say there is a software upgrade.

 

[canuck78]

Why?I have driven my previous e28,e34,e39 without traction control in excess of 200km/h with no issues.And I am still driving my
e60,also without traction control ,also in excess of 200km/h with nil issues.Must the F10 traction control be switched ON to
be able to be driven at a "mild" 160km/h?

Read this:
http://www.roadandtrack.com/car-culture/a28714/turning-off-stability-control-is-one-of-the-dumbest-things-you-can-do-in-a-car/?src=social-email

The traction control on modern day cars is there for a reason since you are driving high speed on public roads/highway.

You must be quite skillful since you had been driving with e28, e34, e39, e60 and f10... it's your choice and your car, BUT consider your own safety, your family and other road users.

If you wanna turn if off, do so on a closed track to test your skills.

 

[canuck78]

That is the problem, i did the alignment but could not find any problems. All within spec. The thing is if it is an alignment issue, turning iff dsc will make the problem more pronounced, but does not, which leads me to believe that it could be somewhere else. Nobody had has this problem before? I have been checking other forums, and some say there is a software upgrade.

Given your rear alignment is fine. Have you check other components of your suspension: any loose or broken spring, sway bar, or retaining mount problem?

Suspect to be hardware related rather than software, but won't rule that out since the UDM is quite a sophiscated ride.

Finding gremlins always going to be ... Not easy.

 

[beemerback]

Didnt experience this on my car. I think you should get it checked at the dealers. BTW what year is your car?

 

[rubes72]

Car is 2011. I have checked all these. But will check again, maybe do a bit of intrusion diagnostics. Anyway thanks for all the input. At least I know it is not normal

 

[rubes72]

Car is 2011. I have checked all these. But will check again, maybe do a bit of intrusion diagnostics. Anyway thanks for all the input. At least I know it is not normal

 

[astroboy]

Next thing to do: On-wheel balance

If that fail, I would swap my wheels to check if rim and tyres are the culprit.

 

[SilverBullet]

My experience would be tyres/wheel issues...just changed tyres? tyre defects? whats the tyre pressure? rims/tyre width, could it be tramlining? (my datsun has lots of tramlining, gotta really grip the steering wheel at times), I would guess the problem is mostly related to tyre pressure, COLD tyre pressure that is..try running 36-38psi cold pressure all-round...don't trust shops or mechs, must do this yourself...if all fails then go for more expensive options such as steering angle sensor, traction control system interfacing, etc...do update us when the problem has been rectified

On another note, when traction control off, even at straight roads, pls be gentle on the accelerator...I have fishtailed a few times on a straight road even with traction control on...due to the sudden torque

Just my 2 cents..



p/s: when that happens, just release the accelerator (try not to jam on the brakes, a slight tap is still ok (tried this once just to test the myth)) while at the same time counter steering as fast as possible to match the car's turning rate..the car will correct itself (with the help of ESC/DSC available in most modern cars nowadays) after a couple rounds of daredevil moments

Even with traction control (DTC) off, DSC will still always remain active to protect the driver and the car

 

[airtube]

Rubes72,

Greetings.

A few points to consider:
1. Possible crosswind where you were driving causing car to sway.
2. Suspension damping plays a role in toe change rate and camber change rate. Advisable to change dampers at 80k km. How is your suspension condition.
3. Tires may cause these problems as production quality varies for every tire especially cheaper asian produced ones.
4. Front toe angle is zero, positive or negative?

I would suggest you to alter your front toe angle and try out at both, positive 0.1 degrees and negative 0.1 degrees toe angle.
Do not forget to check setback and thrust angle. Also difference between left and right angle should not be more than 30 minutes if I am not mistaken. Rims offset should be original to maintain scrub radius.

Hope it helps

Cheers


Deep DeEp @ Heisenberg

 

[alantiong]

are u guys reading this properly??

he mentioned there is a difference when traction is turned on and off....

either he doesnt know shit what is he talking about or not use to the dynamic steering.

I agree with alignment can be a culprit as BMW are known to be very sensitive about it..

But why anyone wanna turn the traction control on and off in the first place?