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Z4 Notchy Steering

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Alan M View Drop Down
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    Posted: 25 Apr 2010 at 7:06pm

I have a 2005 Z4 2.0i SE Roadster, with just under 30k miles; have owned it about 8 months but until recently had not done a lot of miles in it.

It has a problem where the steering goes notchy, so if you are driving in a straight line, particularly on a motorway or dual c/way, its can be difficult to make a small adjustment because the extra pressure can make you oversteer and same when you correct.
 
This problem seems to occur when driven in cool conditions with top down and heater on (runs at a highish temperature to meet ave setting with top down); and after about an hours driving. It does not seem to happen in local driving or if driven over distance with top up, or with top down and heater off.
 
The car is still under BMW's used car warranty and I have it booked in to a main dealer to investigate, but understand that it is a known problem and there can be a reluctance to recognise it.
Anybody had any experience of this Z4 steering problem and what the solution is ??
 
Any help would be much appreciated
 
AM
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Tony View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tony Quote  Post ReplyReply Direct Link To This Post Posted: 26 Apr 2010 at 11:23am
I've seen posts about it on the Z4-Forum, but not read much about it myself as it seems to only relate to the 'electrionic power steering' of the non-M versions. I'll see if I can find some info on the other forum and post it here.

Right, it seems that the various resolutions have been:
1) new steering column;
2) ECU reset;
3) steering angle sensor;
4) all of the above.

Your dealer should be able to do a 'PUMA' (BMW technical support application) submission and find out where & when this has happened before (there's at least 20 members on the Z4-Forum that this has happened to), and see the suggested resolutions. If your car is under warranty then all well & good, otherwise you're looking at a 2k+ bill.

Supposedly the post-2004 cars didn't have this problem, but the ones that have had a new steering column haven't had any problems since.

Z4 steering thread
Thread with some PUMA reference numbers for disbelieving dealerships

Edited by Tony - 26 Apr 2010 at 11:52am
2006 Z4MC
Individual Ruby Black, extended Champagne leather, Piano Black trim
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Mike Fishwick View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike Fishwick Quote  Post ReplyReply Direct Link To This Post Posted: 26 Apr 2010 at 11:35am
There was a massive recall in the USA to replace ALL Z4 steering systems - the rack and electric/electronic parts.

The problem was that the electronics had 'aged' and in high ambient temperatures the response was erratic.  Typically, no power assitance was provided in response to a small steering input,  causing the driver to apply more effort, when the steering system would respond, causing the car to swerve across the road, and the driver having to compensate, with similar problems in the other direction.

It was stated by BMW that the problem would not occur in the UK and Europe, due to the lower ambient temperatures experienced, but it can become just as hot in a central European summer. 

Perhaps their spokesman had not thought about the fact that in the UK the steering motor and its electronics are in close proximity to the exhaust manifolds.

Maybe later cars have the PAS electronics sited inside the car - behind the glove compartment with the restof the electronic modules.  If so, perhaps the heater setting you are using is heating the PAS control unit and so causing this effect.

If the dealer replaces the steering system, be prepared for problems if  the software issue of the replacement system sets up a conflict with the other digital systems on the car - I read of one Z4 owner who had a new climate control module fitted, after which he had no power steering.  It took many dealer visits before an engineer from Germany was flown over, who took ten mintes to diagnose a software conflict.

What a load of rubbish this system really is! One would have thought that a steering system would be of the highest integrity, and of proven reliability - it's a good thing that BMW do not manufacture aircraft!

Just wait until these cars become old.  I really think the entire 'Efficient Dynamics' package is just a con trick to impress the technolgically illiterate! 

Compared to this sorry effort, a hydraulic system works well, is cheap and reliable, and any problems can be easily diagnosed.  As for the 'Energy Saving' of an electrically-assisted steering system, the reduction is not much.

When no steering effort is required - in a straight line - a normal hydraulic PAS pump is usually running with its relief valve open, and consuming very little power.  I bet BMW are comparing the power consumed by an electric system when travelling in a straight line, and that used by a hydraulic system at full lock,  Numbers can be used to prove anything.

A hydraulic system can also be made sensitive to both speed and steering angle - as was shown to the world by Citroen on their SM flagship, during the early 'seventies. 

The SM had two turns of the wheel for lock to lock, with full PAS at full lock, reducing to zero at the straight ahead position, and also full assistance at rest, reducing to zero over 50 mph, a combination which provided what was probably the best assisted steering system ever built - with no pointless electronics. 

It's a pity that BMW do not take note!

 



Edited by Mike Fishwick - 26 Apr 2010 at 5:36pm
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safe1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote safe1 Quote  Post ReplyReply Direct Link To This Post Posted: 26 Apr 2010 at 6:12pm
So if you live in death valley USA, AG will accept claim that the system is Unfit for purpose---live in UK and suffer same problems, its the owners fault----------YOU couldnt make it up, could you????.
 
AS ALWAYS, the problems that American owners have, are considered VERY carefully by BMW NA due to the instant nationwide class action just waiting to happen by those No win/No fee lawyers , in Europe All owners are expected to --get lost--and payup for AG,s mistakes.
 
AS Mike suggests, RHD cars have the important gear close to heat souce manifolds.
Gofastsafe
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Mike Fishwick View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike Fishwick Quote  Post ReplyReply Direct Link To This Post Posted: 27 Apr 2010 at 9:43am
If you want a good tale of BMW sloping shoulders after a poor design made its way into production, look no further than the infamous Servo Brake System introduced on the motorcycles in the mid-'nineties.

Basically, a light touch on the brake lever or pedal caused the ABS pump to come in at full power, the ABS system then saving the day.  True, it gave mighty braking effort, but modern motorcycles are not exactly renowned for having poor brakes!

As you can imagine, it was very difficult to operate the brakes lightly - it was an 'all or nothing' system.

As the brakes were coupled, it was possible to do a 'Stoppy' - standing the bike on the front wheel - by using the brake pedal, which normally only works the rear brake.

BMW(GB) tried very hard to persuade BMW(AG) that it was desirable to be able to work the rear brake independantly (which helps to keep the bike upright) when riding at very low speeds, or when performing a U-turn, but the Germans thought they knew better.  The only riders who need to ride slowly or perform U-turns, so they stated, are the police and military, whose bikes were specially equipped.

Naturally, the entire system - hydraulics and electronics - were groped together in one module, which had to be replaced en masse - a simple failure could easily cost over 1000.

If the servo system failed, or stopped working because the battery voltage fell below the normal level, the braking system lost 75% of its normal power.  Of course, BMW  would never admit this - they stated that '25% of normal braking power is retained!'

A friend found this out one night, when his alterator belt snapped, and he was left with virtually no brakes. Even forgetting to turn the ignition on before wheeling the bike out of its garage meant that there were virtually no brakes to stop it with!

Eventually the system was 'superceded' - but it took many years before this flash of sanity penetrated!


Edited by Mike Fishwick - 27 Apr 2010 at 2:06pm
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Alan M View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Alan M Quote  Post ReplyReply Direct Link To This Post Posted: 08 May 2010 at 8:45pm
Many thanks to all who responded to my Topic concerning my Z4 Notchy Steering.
BMW have now replaced the steering column under the manufacturers used car warranty; I am sure that the background information that you all provided was of value as the dealer had not had previous experience of this problem. But I was able to give them the background plus PUMA references, and within 3 hours of the car being left with them they called to advise BMW's positive response.
Interestingly, whilst I have not yet replicated the conditions that the problem occurred under, the steering seems to be much better; previously over a bumpy road it had a real tendency to 'wander' and  sometimes could be quite difficult to control, I put it down to the 18" wheels and run-flat tyres. It now seems to be much more controllable, anyway hopefully the original problem is now sorted.
Once again many thanks for the advice, which certainly confirms the value to members of the BMW CC Forum. 
AM
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Mike Fishwick View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike Fishwick Quote  Post ReplyReply Direct Link To This Post Posted: 09 May 2010 at 11:35am
Glad you didn't have to pay for it yourself - but just imagine the situation in about ten years time, when BMW will slope shoulders on such problems.  A new column unit will probably cost about 1500 now, and more in the future.

I can forsee the current range of BMWs depreciating at a great rate after they reach about five years old.
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