2003 BMW 530i auto, sport package, 135000 miles.
When we first got this car, it drove like a dream. Crisp, solid, precise. And so it was until one day my son hit a pothole with it, Immediately afterwards, he said the steering felt different. We took it to a trusted mechanic who gave it a very good looking over, and he concluded that nothing was wrong. Nothing damaged, nothing bent, nothing out of alignment.
I told my son that perfection was a thing not found in this world, and that he should enjoy the car as it is.
So, I drove the car today, and it's still wonderful. But I got to thinking that maybe the steering was a little more "loose" than before. That maybe some tiny bit of center vagueness had crept into the equation. The car is still a joy to drive. It tracks straight and steers with a delightful precision. But still....
So, if we are to indulge ourselves in this problem that isn't a problem, what would we presume to be different? If we were to chase perfection, what part sustained some tiny bit of damage to make the steering feel just a little bit "lighter" and perhaps less precise?
My heartfelt thanks to all who offer an opinion here.
You can have nothing broke or bent but still move the alignment.
This definitely sounds like alignment. It may still be within fairly loose factory specs, but did it actually get put on a rack? E39 control arms are already so wiggly it's hard to spot one that's bent, and it really doesn't take much. I've had a known bent Miata arm in my hands and I could not identify the actual deformation.
I hear you on the alignment thing, but it feels more like there is simply less resistance in the steering. I remember the first BMW I ever drove was an E30 325is, and it was like "Whoa, the steering effort on this thing is crazy high!" But then the clutch effort was high as well on that car, but so it is with BMWs and this E39 was more or less just like that, until this event which has somehow caused the steering to feel "lighter." But I suppose a slight adjustment to the alignment could cause that and not manifest itself as a "problem" per se--the car still tracks perfectly straight.
I would guess that moving toward toe out would decrease steering effort around center. Since front toe in means stable (strong centering force) and front toe out means unstable (less centering force).
Keith Tanner said:
This definitely sounds like alignment. It may still be within fairly loose factory specs, but did it actually get put on a rack? E39 control arms are already so wiggly it's hard to spot one that's bent, and it really doesn't take much. I've had a known bent Miata arm in my hands and I could not identify the actual deformation.
this. E39 control arms are notoriously sloppy and complicated. You definitely hit something out of whack and/or bent something.
The single most noticeable and best money spent on my 540 was on a good 4 wheel alignment and new tires. I didn't know just how bad the steering and chop was until I drove the car when it was all fixed.
Get an alignment, drive it if they can hit their numbers. If not, somehtings borked and you'll need to decide how many parts you want to throw at it.
In reply to golfduke :
It may go back in at some point in the future for an oil pan gasket and new front struts. When that happens, I will definitely have them align it. For now, unless it eats the Michelin Pilot Sports, I'm leaving it alone.
These cars run high caster numbers. Less caster usually means less effort to turn the wheel. I would check that.
Also maybe check the strut tower on the side he hit the pothole. Not sure e39s, but e36 and e46 are easy to bend.
Waiting for visible tire wear on Pilot Sports is an expensive way to check alignment. I'd get it on a rack ASAP. Alignment is a consumable :)
Keith Tanner said:
Waiting for visible tire wear on Pilot Sports is an expensive way to check alignment. I'd get it on a rack ASAP. Alignment is a consumable :)
Agree completely. The roads are so awful here that even missing every pothole still means at least 1 annual alignment.
Yah, but....
It's only been like a year since the lower control arms got replaced with some nice new Lemforders and the car was aligned. Whatever changed was by now several months ago, and the Pilot Sports in question came with the car and have to be near half gone already. Also, the car isn't going to be seeing a lot of miles and drives straight and true, so I'm not looking for it to eat tires. Truthfully, the new struts will probably be on the car in a year or so, and by then it's going to be wanting tires too. I'll get it aligned when that happens.
With the addition of the conversion van, the fleet has swollen to a record eight vehicles, seven of which are running and roadworthy. We need to pace ourselves.
I bet the rack steering took a shot to a bushing or the torsion bar or the valve housing and will only be fixed with a new rack.
02Pilot
UltraDork
7/15/21 6:19 p.m.
IIRC, the E39 front suspension is only adjustable for toe, so unless that's it (and it well might be), an alignment may only tell you that something's bent, but not be able to correct it.
On the plus side, if something is bent, and you happened to buy your parts from FCP Euro, you can always send it back for a free replacement (no affiliation, just a public service announcement).
02Pilot said:
IIRC, the E39 front suspension is only adjustable for toe, so unless that's it (and it well might be), an alignment may only tell you that something's bent, but not be able to correct it.
On the plus side, if something is bent, and you happened to buy your parts from FCP Euro, you can always send it back for a free replacement (no affiliation, just a public service announcement).
As it happens, I think I've bought everything I've bought for this car from FCP Euro. 
