jsal

I can not comment on a comparison for the cornering between the two as I have not done a side by side slalom course, however I feel the corner of my e60 is outstanding.

What I can comment on is that the ride of my sport suspension compared to an E39 with sport suspension is much smoother. You don't get the harsh ride on the freeway.

IMO it is a worthwhile option.

heezy545i

I have dynamic drive/ARS, but if I had a choice, I would have gotten the M Sport Suspension.

UUronL

It's not really a primitive active suspension since it isn't meant to replace springs or struts. It's simply an active roll stabilization system... and a sophisticated one at that. This is exactly what it's called in the US - ARS. Active Roll Stabilization.


It "tunes" the amount of effect one would expect from a roll bar (and even decouples it completely) based upon lateral acceleration.



This system also improves the self-steering characteristics of the car. This translates into requiring less steering angle to achieve the same amount of lateral cornering. I have posted a .pdf (as have others) numerous times, so I won't re-post. Do a search and you can find a very detailed two page article from a scientific journal that outlines it very concisely.



.90g of lateral acceleration on the skidpad for a US 530i Sport with Dunlop RFTs is pretty darn impressive IMO. That's actually better than the .89 that the M5 does... Same periodical testing with the same methodology. I think the non-sport does something like .72 or .74g. I'd have to check old posts to see for sure.


I find that the car delivers a great sensation when you press it hard into a corner. It seems to squat and feels like it is glued to the road. Very confidence inspiring. The car is very capable with DD. I hate body roll and brake dive, and it mitigates these kinds of sloppy dynamics completely. In fact, the system has to artificially introduce it near the limit to keep the driver aware of the limit - it could actually expunge all roll completely.

aybeesea

Thanks for the contribution. It makes much sense and gives a good insight.

ABC

swajames

I 'm pretty sure the non sport is around .82. I'm not sure where you get the some of your info from, I agree that ARS is great but it can't and doesn't totally eliminate roll. It's reactive and not predictive, and quick steering input can catch it out. ARS also does not impact brake dive - every E60 suffers from that, sport or non sport.

UUronL

You're right - as I said, you'd have to check my old posts - .82 does sound closer to what I remember come to think of it. I also always seem to lump brake dive in there, but you're right - it doesn't (and shouldn't) have any influence on brake dive. I feel the E60 is pretty good and doesn't dive too much, but opinions probably vary depending on what you're used to.

It doesn't completely eliminate body roll as you said (I should have qualified my statements better), I made it sound as if it were 100% gone when I meant that objectionable or sloppy lean is totally gone. Car and Driver went as far as calling the E60 with Dynamic Drive the flattest cornering car they had ever driven.

The system is reactive, but aside from the fact that it's very fast to react, the system does quite a bit of prediction to ensure proper behavior. Besides, I don't think it needs to react constantly and make continuous radical changes.


I went to the trouble of locating the first post where I saw the .pdf - Stream posted it:


http://forums.e60.net/index.php?s=&sho...st&p=169742


It contains much of what I have said and is where I got my info from.

swajames

We're on the same page. I certainly agree with with you that ARS pretty special, it does make a genuine difference. I suspect it's even more noticeable in the I6's but even in the heavier V8 the benefits are
obvious. That said I'm still persuaded that some of the lateral G enhancements are due to the better (and in the case of the V8's wider) rubber on the sport tires compared to the all seasons on the non sport E60s. ARS makes a difference but I'm sure the tire differences also factor into the equation.

wmhandy

I believe that I can HEAR my ARS system in action. I am about to bring this to the attention of my service center.

I swear I hear a high pitched constant-rate squeal when the car is entering into, and exiting out of certain attitudes that would normally call the anti-roll bars into play.

As the suspension loads up I hear it, then it ceases while no state change is occurring and then starts again while the car returns to straight and level and finally ceases until next attitude change.

Sounds similar to a brake squeal but is always constant-rate regardless of car speed, acceleration or deceleration.

Don?t you think I should be able to disable ARS by killing all DSC? Then I could run same road sections expecting auxiliary noises to be gone. When DSC switch is held down until scary warnings appear it means ALL active systems are shut down including steering, roll and traction, correct?

I think the hydraulic slave motor connected to the anti-roll bar ?differentials or actuators?? is making the squealing noises in my car.

BTY, those anti-roll bars have to be split in the middle right? Then they are really just independent but variable torsion bar springs.

I find squeals, squeaks and rattle un-acceptable and I laugh in the face of any manufacturer who tells me the sounds are ?normal?. I ask you? are the noises included on the standard features list?

Thank you, I feel better now!

UUronL

You can't disable ARS, so the test you want to run isn't possible.


I think your hypothesis is sound - I can always hear subtle things very well, and I have never once been able to hear anything like you describe. It is very possible that one of the components is making some noises that it shouldn't be making.

Rudy

And I went to the trouble of locating another thread about this topic:
http://forums.e60.net/index.php?showtopic=15085