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Car Forum / BMW Cars / April 2007E39 suspension problem
I am experiencing a strange problem which what I believe is my front suspension. When going over rough road while braking lightly, the suspension seems to go into resonance and the ABS cuts in even after leaving the rough surface. Doing the same thing without braking, it resonates - but less so. Braking while driving down a rough relatively steep incline is where is is most noticeable. I thought at first it was something to do with the ABS but I now think the ABS is a symptom of the suspension issue. The MOT garage tell me the suspension is OK and it (apart from said fault) drives OK. Is thing indicative of something I am missing? >I am experiencing a strange problem which what I believe is my front >suspension. [quoted text clipped - 9 lines] > drives OK. > Is thing indicative of something I am missing? I'm guessing a wheel-speed sensor (ABS/DSC/etc.) is flakey, or has a loose connection. FloydR >> I am experiencing a strange problem which what I believe is my front >> suspension. [quoted text clipped - 14 lines] > > FloydR I thought this too but as the resonance problem is also present when not braking I doubt it albeit braking makes it worse. If the wheel is bouncing during the suspension resonance, the ABS may mistake it for locking up? > I thought this too but as the resonance problem is also present when not > braking I doubt it albeit braking makes it worse. If the wheel is > bouncing during the suspension resonance, the ABS may mistake it for > locking up? E39's just seem to do this under certain situations. It may be made worse by wear in the front suspension components (bushings and ball-joints) and by low-profile stiff sidewall tires. Some E39's seem prone to it - some aren't. If you have over 60,000 miles on your car - it needs new front lower control arm bushings, and the ball joints at the end of these arms may also be worn. Common and predictable - also leads to a shimmy at 60-70 MPH that can't be solved by tire balance. > > I thought this too but as the resonance problem is also present when not > > braking I doubt it albeit braking makes it worse. If the wheel is [quoted text clipped - 10 lines] > also be worn. Common and predictable - also leads to a shimmy at 60-70 > MPH that can't be solved by tire balance. Check a specific E39 resource or maybe even www.e38.org. Wear in the suspension can cause symptoms even if everything looks alright upon inspection. >> I thought this too but as the resonance problem is also present when >> not braking I doubt it albeit braking makes it worse. If the wheel is [quoted text clipped - 10 lines] > also be worn. Common and predictable - also leads to a shimmy at 60-70 > MPH that can't be solved by tire balance. thanks for this info. Useful. Is there any more detailed info on it as I can't find any! Perhaps I am searched on the won key words. Mileage is 80K an it has a 3.0d lump in it. What about shock absorbers? resonance seems consistent with some sort of failure with the shocks (although generally, the ride is OK). Perhaps the bumps hit a certain repetition rate to spark if off? >>> I thought this too but as the resonance problem is also present when >>> not braking I doubt it albeit braking makes it worse. If the wheel is [quoted text clipped - 16 lines] > failure with the shocks (although generally, the ride is OK). Perhaps > the bumps hit a certain repetition rate to spark if off? Certainly shock absorbers are also part of the equation. The 5 series has been known for superb handling and ride qualities - they got this way by having very compliant front end components. If some of the components get too compliant there is always the possibility the suspension won't behave the way it was designed to. Putting any of the components back towards the factory configuration will help eliminate any suspension movements that are out of the expected range. Do a search on Yahoo groups for E39 - you may find help there. Traction control cutting in too? >> I'm guessing a wheel-speed sensor (ABS/DSC/etc.) is flakey, >> or has a loose connection. [quoted text clipped - 3 lines] > braking I doubt it albeit braking makes it worse. If the wheel is bouncing > during the suspension resonance, the ABS may mistake it for locking up? > Traction control cutting in too? > > Good question. I 'think' I recall seeing the DSG light illuminate but will monitor more closely (I'm usually trying to see the road surface for specific causes!) |
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