All good points! I haven't changed one thing at a time and I never got it properly dialed in after it was lowered which makes it tricky to diagnose. The other thing that is a real pain I seem to struggle to get out when there's no traffic which makes it really hard to repeat the symptoms and accurately define them. I'm fairly comfortable that deep down the car is basically pretty well balanced now - better than it has been since it was lowered. We've been through a lot together often at a significant pace so this is a car I know very well. I also had an E46 for over 10 years before it so I know all about the tyre issues. I've previously never found the rear to be very sensitive (even with tired Bridgestone Potenza's - I could live with them till they were on the limit) the real problem was the front. At the moment I wouldn't want my wife (or anyone else that's not ready for it) to take it on a fast road.
MrPT
I came across this description of “tire pull”
Interesting. I guess if you extrapolate this then tyres warn unevenly (even if the same on both sides of the axle) would definitely cause problems but I just don't believe that's the main issue.
The feeling of all the weird behaviour being specifically in the rear is much less pronounced now. This improvement would seem to have been a combination of upper wishbone bushes and damping. I suspect the biggest factor was a difference in the damping left to right (not sure how that changed
). It is a pretty hard ride which is not nice for hours on the motorway but I could live with that if it didn't scare the sh*t out of me! To Jembo's point - I'd check your shock absorbers.
The only things that are not new are the subframe bushes, the engine mounts and the inner ball joints on the steering rack but it's just been MOT'd, specifically inspected by BMW (when they were in the doghouse) and I've looked as closely as I can. It's all in pretty good condition so I really don't think the problem is there.
It's quite possible that there are a combination of issues (e.g. tyres might help a bit) however, to take one thing that I clearly experienced several times. I definitely noted on several long motorway bends where I stayed in the middle of the lane (so little if any moving over the ruts) the same sensation. It was like being pushed sideways, then it stopped, then it happened again - three times which was when the road straightened out each time. Like I said a bit like driving too fast in a high sided van that doesn't have a lot of weight in it. However I'm becoming increasingly sure this is related to the power steering. It was too regular and firm to be anything alignment related (e.g. toe-in) or slack (in a worn bush). After all the suspension was loaded up and there was no mid-bend steering input so really the car should have been stable at this point. Whether this is related to the fidgeting in a straight line is another matter.
So I think I need to explore the power steering and possibly (although there are no lights) the DSC. It will probably be tricky to find a piece of road where i can recreate the problem and see if anything is different after pulling the fuse out but I think that's the next step.
I keep telling myself that if I buy a 911 or even a Panamera it would be no guarantee that there wouldn't be problems.....
Coupe, KW coil overs, PSB limiters, Powerflex ARB bushes, 18" CSL reps, Aero skirts, ZHP leather knob, Whippy and proud. Probably needs a wash