Hi all, I have an 07 z4 coupe and despite searching the web long and hard I’m still no closer to finding out what the issue is.

Basically when I’m traveling on the motorway at 60-70mph my steering becomes very twitchy and not very nice to drive. This is the only time it happens and as soon as I accelerate or lower my speed below 60 the problem goes away. I don’t use run flat tyre and my tyre pressures are exactly what the manual states.

Really hope it’s not a steering rack issue but wondering is there some kind of electrical fault here as it’s twitchy only at that speed, even at 80mph the problem isn’t there but steering does feel light. I don’t think it’s control arms or bushes as I don’t feel like the wheels are moving to match what the steering wheel is doing when the random twitching is happening.

Hopefully My post makes sense 

Thanks for looking. 

Hi Karl

This are some extracts I found on various sites

Quote

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 assistance 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.  
Maybe later cars have the PAS electronics sited inside the car - behind the glove compartment with the rest of 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 minutes to diagnose a software conflict.

Also this link may help

http://www.power-steering.co.uk/bmw-z4-electric-power-steering-column-repairs-replacements/

Thanks for the link. It’s surely an electrical fault and not a mechanical one because the problem only happens as soon as I hit 60. Hopefully this sorts it. 

Let us know how it all goes......would be nice to know the outcome

Welshz4coupe     Hi, has there been any solution to this? I have precisely this problem.