Quote:
Originally Posted by BimmerGuyFL
Hmmmmm this is an interesting topic. Previous Generation BMW's suffered easily from this same problem. The E39 5-series from 1997-2003 was notorious for this. It could be that when they switched from the E90 platform to the F30 platform, in an attempt to make the ride quality smoother and more absorbent, that the front control arm bushings are softer. Therefore giving the control arms more play (shimmy) in that vibration frequency (40-60mph). The E46 had pretty soft bushings and it rode better than the E90 but a lot of the times these bushings had to be replaced cause since they were softer it would absorb impacts more at the bushing instead of transferring it through other components. By 25K thru 35K miles a lot of E46 needed bushing replacements. When the E90 was released I remember reading that the bushings were stronger but not as absorbent as in the E46 which caused the E90 to have a firmer ride, yet most E90's never had this SHIMMY at the steering wheel problem in general.
So.....IMO I would say that the problem lies at the front lower control arm bushings not being strong enough to keep the car from shaking at those speeds.
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It is not that- many have driven these cars with no issues. I've tracked it and taken the car all over the place and never felt a vibration (abusing it every second I was in it).
There may be a bad batch of steering systems or rims or something along those lines. If it was a bushing it would be felt continuously whatever it is it is out of trueness or balance- it also could simply be the roads of an area and "tram lining" when the car gets in the light ridges of the road it can pull or vibrate. Happened to me all the time in my E90 ZSP in certain areas but then would vanish on new pavement.
This is not a global problem so it is not a gross lack of engineering. The issue with the E90 was never really the bushings anyways it was the RFTs not absorbing anything and transferring it to the bushings causing them to fail- if they made them any harder or softer the issue would still have been present the tire brands did not meet the specifications at launch. The new RFTs feel little difference to standard low profile tires so that is not the issue.
The E60 had steering angle sensor issues at one point that had similar symptoms. If Fleet says there is already a different part then they may have made an engineering change although I am sure it is because of all the negative reviews the car received for steering and they went with the upgraded rack/software from another model (Z4 35IS).