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2010 2011 BMW 5 Series Forum F10 Dynamic Handling Package: Why it's the Best BMW Suspension Money Can Buy |
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07-05-2014, 04:19 AM | #23 | |
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Where I see the adaptive systems being superior, for daily road use, is the wider working envelope as you drive. Besides the adaptive 'on the fly' function, we have the different suspension modes, adjustable from the seat. The continuously adaptive ability gives greater comfort over varied surfaces, even in a given mode, let alone the choice of how you want to feel the road (or not) as you drive. Setting up a good coil system still leaves you with that setting from the seat, whatever the surfaces you have to drive over on a given trip. That for me is still a big compromise. In my E91 wagon I fitted Koni FSD (Frequency Selective Dampers), which appealed to my desire for a wider working envelope with a passive system. Convinced me, after driving over 30k miles on them, that for my next car I'd be looking at the adaptive suspension systems. VDC copes with the damping variables, but it is ARS which (IMO) is the star of Adaptive Drive. Roll bars which can be tuned as you drive in response to demand does so much more for a large car than any damper system on its own can do. The ability to decouple for single wheel bumps, but at the same time to tune front to rear bars to keep a neutral handling balance and only tune in a bit of understeer as you drive harder. Works for me to have a 5-series wagon, driving much like a 3-series, helps lose the bulk of the car and at the same time improving the dynamics and comfort where it matters. OK, so we can upgrade the roll (sway) bars in a passive system, but then we just move the compromises, even start tightening the working envelope. As we know stiff bars are not all gains, there are negatives. I suppose it depends on whether we want to spend the money on aftermarket parts, experiment with setups, and accept the new compromises we have added. Or take the BMW developed system, and accept the inherent compromises, if we se them as such. I have chosen the latter, the fact I can toggle to a different suspension mode when my mood changes, or the road surface quality dictates, is my best of all worlds. HighlandPete |
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07-05-2014, 05:54 AM | #24 | |
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I know the 850 CSi from 1993 had active rear wheel steering, and that made such a difference that it would outperform just about any car of its day in a slalom course. Even today the handling of that car is impressive. This video shows that system running a self test on my friends CSi. |
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07-05-2014, 06:14 AM | #25 | |
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I used to do a lot of track driving when I was in my 20's so I have had cars with fully adjustable suspensions. Camber plates, Blistein pss9 and KW v3. And if you dont know what you are doing, you can mess up the cars handling so bad with those suspensions that you will end up with a dangerous car. I have tried some setups that appeared good for regular driving, but as soon as I started to push the car it started to wobble and acted more like a boat than a car, because it was too soft in one direction. On the other hand I have also adjusted the car to be rock hard, thought it was great untill I ended up off track because the grip was gone in an instant without any warning. On my KW v3 I ended up with the default recommended settings, as everything else I tried did not work out. Either being to uncomfotable, or ruining the corner handling of my car. I ran with a setting for a year thinking it was a good everyday setting, then one day I pushed the car with 2 passengers, and I nearly wet myself because the car almost wobbled off the road. Turned out the "bound" setting was a little too soft. If you have no clue about how to set up a suspension, getting a fully adjustable one will probably lead to two things. You run a default setting, so you might as well have got a non adjustable one. You end up with a car that handles worse than stock, but has a nice drop. |
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07-07-2014, 05:12 AM | #26 |
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DHP effect on wheel/tire damage
Digitalnoah/ezmaass,
Your profiles indicate Northeast US locations (and the corresponding rough pavement) so hopefully one or both of you can comment on this question. When encountering a rough patch of road ahead (on a highway for instance)the instinctive response is to hit the brakes in an attempt to lessen the damage to the wheels & tires. This causes the front of the car to dive. I would think Adaptive Drive would respond initially to the dive by stiffening up the suspension, aggravating the problem you are trying to lessen by slowing down. What are your experiences/thoughts around this? I'm all for avoiding handing "like a 1980s Buick" but am not interested in replicating Autoweek's experience with the F10 (7 RFTs replaced in 9 months): http://www.autoweek.com/article/2011...IEWS/111229921
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07-07-2014, 09:26 AM | #27 | |
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1. Suspension has no effect on tires/wheels. What ever impact the tires/wheels receive has already occurred, and the job of the suspension is to diminish the feeling of the impact to the passengers in the car. So avoiding big pot holes to protect your tires/wheels is important no matter what suspension you are running. 2. The goal of adaptive drive is to keep the car level, flat, and square, reducing the effects of a brake-induced nose dive, a cornering-induced body roll, or a pot-hole induced bounce. This youtube video (4 of 4 in a whole series) explains the technology pretty well in the context of running over bad spots on the road:
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07-07-2014, 09:59 AM | #28 | ||
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The dampers may stiffen instantaneously on the front to prevent dive (no idea on the actualy program), if this is the case, the tire and wheel are subjected to GREATER force than if the damper was soft Quote:
Stiffer dampers CAN mean more tire damage. |
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07-07-2014, 06:02 PM | #29 | |
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I don't know if the system actually works the way you're describing, however. Do the dampers stiffen on nose dive? I don't know... but I'm doubting it's correct. There are two parts of the system here that make up DHP: - Electronic Dampers - Active Roll Stabilization The dampers, as far as I know and can tell in practice, are only set to a particular stiffness via the Dynamic Drive rocker switch. So, if you set them to Comfort+, they're going to be soft. If you set them to Sport or Sport+ they're going to be stiff. I don't believe they'll change stiffness on their own. I could be wrong. If they do, I haven't noticed it, and it would have to be very instantaneous. Keep in mind that the dampers control RECOIL only. The spring rate is fixed. So I highly doubt that the car would change the damper rate to help with a nose dive... someone correct me if I'm wrong here? Second is the ARS. ARS only works laterally in cornering as the name implies. It can't work front-to-back. There are active sway bars that twist and create torsion to counter the forces applied to the car in a lateral acceleration situation, helping to keep the car's body from rolling side-to-side. But, since this would have no impact on a nose dive situation, I don't think this system would come into play either. Again, if I'm wrong - someone please correct me. I'll be happy to play with it a bit and see what happens, but my gut tells me that neither the dampers or ARS would react differently in any driving dynamics mode to emergency/hard braking, as I don't think either system could help. The damper stiffness appears to be manually set only (at least it's been my experience - I don't sense the damper rate changing on its own), and the ARS appears to work dynamically in all driving modes, but it only works laterally for controlling cornering handling. The only thing that would help in your scenario would be spring rate - which is fixed.
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07-07-2014, 07:36 PM | #30 |
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Wow...great thread. I just turned in my 535i with no DHP and bought a 550i m-sport with the DHP. Can't wait for it to arrive and enjoy the difference in handing! This thread just got me ever more excited about my upgrade.
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07-07-2014, 07:53 PM | #31 |
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Ben2k9, glad this thread has been helpful. Were you able to test drive the DHP ahead of time or did you dive in on good faith? I'm hoping this thread leads to more of the latter so that this option becomes more common.
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07-07-2014, 08:40 PM | #32 |
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To be honest i located this particular car over the internet in Miami. It had everything else I was looking for. Since I already had a 535i, any improvement in handling was just going to be a bonus but now I'm feeling great about the feature.
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07-08-2014, 04:48 AM | #33 | |
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The variable map is applicable to braking, cornering, etc. So the question about braking hard does mean to reduce dive, the damping rate will increase, helps to shorten the braking distance with more body stability. In a similar way if we make a sharp turning manoeuvre, say to the right, the left hand front damper (among other functions) will instantly change to a firm damping rate, to slow weight transfer and help reduce pitching and roll. So to the issue of more potential wheel damage, with active systems... I suppose we first have to compare a comfort setting to a "non sport" passive suspension. Clearly we will have an increased front damping rate in the heavy braking event, a reaction we can't have in the passive system. If we are already running a passive "sport" suspension with higher damping rates as standard, then the active damping system will only be stiffening up to a similar rate in that same manoeuvre. Even our active system does not over damp, it can only trigger the firmest setting within the design. From my understanding of suspension function, I don't see Adaptive Drive making braking over rough pavement significantly worse for the wheel loads than the M-sport suspension, (maybe marginally, if the stiffest VDC damper setting is slightly higher than the M-sport damping rate). But more wheel load if we are comparing standard non sport suspension to AD. I feel wheel choice is the bigger issue for wheel/tire damage. It is why I run 18" on my 535i, more rubber with greater ability to cope with rough pavement and road impacts, whatever the suspension we run. HighlandPete |
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07-08-2014, 05:42 AM | #34 |
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I agree as a $3500 option it is pricey, however compared to some of the other stuff it's definitely a top option.
Unless you have plans to go full coilover, which really is the 'hard' option, or want a stripper on just springs -the 'cheap' option. Handling is great on my car, however I am wondering if the variable dampers would eliminate some of the minor floatiness that is residual over larger undulations.. A car of this size definitely benefits from VDC+ARS.. which is why you only get the VDC on the 3 series.. body roll is the major issue with the 5+series.. which ARS solves with brilliance (or upgraded springs if it is not an option) I would recommend DHP even though I don't have it. |
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07-08-2014, 07:17 AM | #35 | ||
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Adaptive Drive works, I rate it very highly in my 535i wagon. HighlandPete |
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07-08-2014, 11:47 AM | #36 | |
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When I get the chance I'll try to see what my car can do on that particular piece of road.. |
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07-08-2014, 06:26 PM | #37 |
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So, I'm still not sure the DHP components would have any affect in a braking situation. I'm not a suspension expert, so someone please correct me if I'm wrong, but my basic understanding tells me this:
1. "Nose Dive" is the result of weight transfer. Weight transfer is caused by the center of mass changing on the vehicle under braking (or acceleration, cornering, etc). 2. The center of mass is impacted by the vehicle ride height (spring height) from the suspension. Bringing the center of mass lower helps reduce the effect of weight transfer. Also elongating the car (longer wheelbase) or widening the car (wider track) helps eliminate weight transfer. 3. Under a nose dive condition, the front springs are carrying the additional load. The spring rate and ability to compress, along with the amount of transferred weight, will ultimately determine how much nose dive occurs. 4. Dampers control recoil (up and down motion) caused by spring decompression. A higher recoil rate (damper rate) will slow (or absorb) the recoil of the compressed spring quicker. A lower damper rate will slow the recoil slower. Net effect - higher damper rate, more abrupt and quick stabilization of a decompressed spring. So, all of the above being true, I fail to see how any of the DHP systems would impact a nose dive... or more specifically the impact on the wheels if one hit a pothole while emergency braking a car with DHP vs. passive suspension. The dampers, even if they stiffened, would only impact the vehicle dynamics after the longitudinal deceleration had stopped - i.e. the driver let off the brake or came to a stop, allowing the car's center of mass to shift backwards and therefore causing recoil / spring decompression. Otherwise, if weight transfer is still occurring to the front wheels, the damper is sitting idle while the spring is compressed waiting to handle the recoil. I suppose BMW's variable dampers COULD increase the damper rate under hard braking with the anticipation that you'll abruptly let off the brakes, abruptly changing the center of mass backwards, and you'll want the car to handle a more abrupt recoil on the front axle... but I'd also imagine this would be a very, very short window. Likewise, it would have to be variable around the "base" damper setting - comfort+, comfort, sport, sport+... and you'd have to be timing that perfectly with hitting the pothole. ARS is only controlling lateral body roll, so it doesn't have any ability to affect anything to do with longitudinal acceleration/deceleration, or therefore longitudinal weight transfer - after all, it's connecting left to right wheels on both axles and twisting to create counter-forces left/right. So, I don't see this system coming into play either. So overall, I just don't see DHP doing anything during a nose dive... or squat for that matter... which would impact the wheels any differently than with a passive suspension. Like I said, I'm not a suspension expert, and this is my rudimentary understanding of how the systems all come together - so if I'm wrong here, please correct me.
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07-09-2014, 02:57 AM | #38 | |
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Think it through with more emphasis on the compression stoke, (on the front axle) rather than the rebound phase. See where that takes your reasoning on the wheel loading during a braking impact. That is why I reason the higher wheel loads compared to a spring with a softer damping rate. But as I said in my last post, I question if the loads will be much different than with M-sport suspension, where the sport spring and damper rates could be just as resistant to the same impact during heavy braking. ARS may help reduce a single wheel impact during straight-line heavy breaking, as there won't be the same resistance to suspension movement as there would be with a passive bar. But ARS will have no effect on an axle wide impact. HighlandPete |
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07-09-2014, 04:56 AM | #39 | |
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If the car is diving, the spring AND damper are compressed at the same time.. this is the only suspension component that resists the dive (excluding sideways movements which would involve the ARBs) If the damper is dead -not resisting at all- the full force is resisted by the spring. If the damper is set on hard - both the spring and damper will resist the weight ..they're bosom buddies. As you can imaging, the damper can have great effects on the handling of the car, as effectively it interferes/compliments the action of the spring. It can effect turn-in, dive, speed bumps etc. One experiment you can try with DHP is to brake suddenly going over rough road that you normally feel some feedback from.. pay attention to if the bumps get larger when you suddenly apply the brake. If the dampers are stiffening in response to brake application, you could feel it through the car in this way. |
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07-09-2014, 10:30 AM | #40 | |
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On dive and lift we mustn't forget the other axle in each case. For example in brake dive, front compression and rear rebound settings are both able to assist in controlling weight transfer. Hence another benefit of adaptive damping, front to rear damping can be optimised for each condition, without having to have hard damper settings all the time. HighlandPete |
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07-09-2014, 02:19 PM | #41 | |
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i live in an area where the roads are damn bad. would you recommend DHP comfort setting or base suspension for the potholed roads? |
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07-09-2014, 02:35 PM | #43 |
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I have a 2013 535 xDrive. I had to order DHP because, as the OP said, the other option was no DHP and no 704 suspension, which is dreadful even to think about.
DHP is pretty cool, and I appreciate the extent of the technology required to make it work. However, I personally have no interest in anything other than Sport mode. I drive it that way 99% of the time or more. Therefore, I would rather have spent less on the 704 suspension and foregone DHP.
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07-09-2014, 05:11 PM | #44 | |
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Thanks for the great explanation!
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