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      08-03-2019, 12:16 PM   #1
bendandthrow
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United Kingdom
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Drives: F11 535d Touring 2014
Join Date: May 2019
Location: West Yorkshire

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Integral Active Steering (IAS) - Only seeing 1 degree movement, is my system faulty?

My 2014 F11 has IAS. However I have to say that in the 3 months I have had the car I have never been aware of it. My previous car was a 2010 F11 and I can't say I have noticed any difference between them so far as low speed steering is concerned.

Out of idle curiosity today I tried to see by how much the rear wheels counter turn when manoeuvring slowly. I parked the car with full lock, got out and had a look. I could not perceive any angle to the rear wheel, whereas I expected a small amount of counter lock (as I had been driving slowly when turning the steering wheel).

I then stood outside the stationary car and turned the steering wheel full lock the other way whilst looking at the rear wheel. I did not see any movement of it at all. I did this several times and never saw the slightest movement of the rear wheel.

I then placed a large protractor like object up against the tyre whilst at full lock. Then I turned full lock the other way and lo and behold I saw a small gap appear of about 2mm. So 2mm at that point on the tyre is the full range of movement. The point on the tyre that I was measuring is at 11cm from the centre so is on a circle of pi x 11 x 2 = 69cm circumference. A movement of 2mm represents about 1 degree around the vertical axis of rotation.

From what I have read the rear wheel should turn by up to 3 degrees in each direction so I should have observed a change of 6 degrees or 12mm, or 6x what I actually observed.

Is this to be expected in this scenario or does it seem the system is under performing? It is hard to believe that a rotation of 1 degree is going to make a significant difference and so if this is normal it begs the question as to how worthwhile this expensive option is. There are no warning lights on the dashboard.

Thanks
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2014 F11 535 Touring