Sticky Steering - yet another thread

[portculisz4]

Having just replaced my failed EPS motor with a suitable replacement (just needed to get the car back on the road before my planned hydraulic conversion next year), I am still unconvinced as to what this ‘sticky steering’ effect should feel like and whether my car is experiencing it. The effect I feel while driving (at normal road speeds) is an over damped feel from the steering wheel and a slight reluctance to fully return to centre when the wheel is partially or fully turned (negotiating road bends, corners etc). The popular solution seems to be adjustment of the eccentric ring between the motor and steering column housing and there does seem to be mixed opinion on the outcome (some say it works some say it doesn’t) as to whether this is the solution to the phenomenon.
I have managed to locate a technical article (the URL Link is below) which describes how the Z4 EPS works and may give other possible causes which may attribute to the ‘sticky steering’ effect, what it doesn’t mention is whether bad adjustment of the eccentric ring is a cause of the problem but does give other reasons as to why EPS power assist may be reduced under certain operating conditions. I noted for instance that there is a damper unit within the steering rack – could this be a source of the effect. Would appreciate your thoughts if you are able to take time to read the PDF file in the link below.
link – https://www.bimmer-service.com/bmw-Z4
download PDF file ‘BMW Z4 2002-2008 Electronic Power Steering’

 

[thecremeegg]

Sticky steering is where the steering feels notchy - it won't return to centre easily and it seems to move like it's a 50p piece instead of a round wheel. Usually it's most prevalent in hot weather.
Numerous theories as to what causes it, some think the column grease dries out, others have fixed it with the adjustment of the eccentric ring. For me I've had it on two different columns and motors and it ruins the car.
What you have sounds a bit like the eccentric ring might need loosening? Mine felt similar on top of the actual sticky steering and so I've ditched it for hydraulic now

 

[portculisz4]

Many thanks for your thoughts, I am going to try loosening up the eccentric ring now I know which way to turn it, I do plan to pursue more info. on the rack damper and whether this is a serviceable area but will do this under a separate thread. Have all the bits for the hydro conversion but have had to delay this year due to family commitments, any tips in advance on the conversion work would be much appreciated (especially the HP hose connection).

 

[portculisz4]

Have adjusted the eccentric spacer ring by about 15mm (CW when looking in towards the front of the motor) and it has made a significant difference but is still nowhere how a modern electric power steering should feel. Will still investigate other further options but will probably put up with it until hydraulic conversion is completed.

 

[thecremeegg]

Yea I could never get mine right, always felt off, you have my sympathies! There are a multitude of people on here that are in denial that this is a problem and are sure that if there are no errors showing then it's fine. I'd wager there are quite a few Z4s out there with shoddy steering that just haven't been diagnosed yet.

 

[tom27]

For me, applying some grease to the 2 universal joints on the column in the engine bay significantly helped this issue. The issue only happened for me when hot.

 

[portculisz4]

tom27 - interesting solution, how did you manage to get grease into the two UJ joints as they are normally sealed ? I plan to look around the rack area by removing the OS rubber gaiter but have also been given a suggestion to use a silicon grease spray on the plastic bearing where the shaft exits through the bulkhead and also at the start of the column just beyond the steering wheel. Reading the technical description of how the EPS works, it would appear that the EPS is sensitive to overheating and deliberately reduces the amount of actual assist which I guess could also contribute to the sticky steering effect.

 

[tom27]

Just sprayed them with grease. I think it has worked for some people based on older posts.