I get how they work in theory (they react to road conditions and adjust the level of damping). But what does this mean in practice? Is it actually making adjustments every second? or just under more extreme conditions a few times per drive? Is there anything i can do to notice these changes happening?

 

I think only the Advance has it. Even the A Spec package doesn't have it, which you'd think it would.

https://www.acura.com/rdx/modals/adaptive-damper-system

 

I have them, but I can’t figure out what they do.

 

They are constantly making adjustments. This allows the suspension to corner flatter without making the ride harsh, and to react to "big hits" relatively gracefully, in addition to tuning the ride for poor road surfaces. But these are not magnetorheological ( MR ) shocks; I believe they employ a secondary hydraulic circuit with a valve plate controlled by a servo motor. Acura claims a millisecond scale response time for the system, and it's always active.

In practice, the adaptive shocks make the suspension feel sporty but supple. And the overall feel can be adjusted with the IDS system. AFAIK there's really no downside other than cost. And yes, they are only on Advance.

Here's something I wrote in a related thread in 9/18. My opinion hasn't changed.

 

A-spec owner here who never test drove the Advance. I do think road noise is little loud with the aspec and suspension stiff. Not a bad thing but the comfort driving mode has room for improvement.

Do you advance owners feel the adaptive dampers working or they meant to be unnoticeable? Is that feature alone worth the added cost?

 

The way it feels to me is that the difference between the A-spec and Advance has more to do with how linearly the suspension firms up as it's compressed. On the A-spec (without the adaptive dampers) there seems to be a linear progression to full compression whereas on the Advance it's a curve that stays a little softer (suppler over small bumps) as it ramps to full compression. There seem to be many factors that play on how extreme that curve is (its tendency towards softness) and how long that curve is (the difference between the softest and firmest damper setting). Sensors will inform the system (throttle, cornering forces, etc.) and the drive mode knob will bias the system.

When I drove an A-spec for a week, my feeling was that, despite the larger wheel diameter, it rode (on average) a tiny bit softer than my Advance in Sport mode. I also felt it was more comfortable due to the linear way the suspension reacted to road conditions.

 

I don't know how anyone could tell, especially going between two vehicles or driving on public roads. I think the only way you could tell what the system is doing is if you could turn the feature on and off (which you can't) and run it on a test track over and over.

 

The dampers are undetectable except in Sport+ mode, where they reduce the body roll markedly. I live in an area where traffic lights have been long banned in favor of roundabouts, and the Sport+ performance in the roundabout is astonishingly different. There is almost no body roll or front plowing, which combined with the quicker steering ratio of Sport+ makes the roundabouts a real treat. Performance in any driving mode is very good, but the difference in Sport+ is more than just 'noticeable'. In the roundabout, the steering has to go quick right-hard left-gentle right in quick succession and the body roll is virtually non-existent. Given how the dampers perform under those conditions, they certainly are reacting similarly in all other movements, I think that is what makes this car feel so solid and confident to drive in all situations. Call me a definite fanboy.

 

If you want to compare, it probably makes more sense to compare Advance to Tech, because the tires, wheels, and rear springs are different on A-Spec.

But I would say the operation of the adaptive suspension is transparent to the user, as intended. Except to the extent that its overall character can be altered with the IDS.

Is it worth the cost? Dunno. It helps push the price into a realm where you could consider other "luxury" sporty compact crossovers. I certainly wouldn't rush out and trade an RDX A-Spec for an RDX Advance without carefully evaluating other alternatives. I'm a Honda/Acura fan, but I'm not completely blind.

 

I have a 2019 Advance and on a rough stretch of pavement, you can feel the difference if you scroll through the drive modes. Sport+ reveals every seam in the asphalt as the dampers go taut. I also agree with the above posts about the cornering in Sport+, it's a marked difference from the already good balance in the less performance oriented modes.

 

The problem is that if you want the performance advantages of Sport +, you have to put up with the childish fake engine noise that they put out through the speakers.
It feels like a five-year-old driving around yelling “Vroom! Vroom!”.

 

I think main reason Advance appears to be more quiet is because of acoustic glass, not because of dampers.

 

As far as I know aspec has the same suspension components and tunning as TECH or base. Advance platform has adaptive dampers, so its the only unique suspension configuration. Please provide reference that says otherwise.

 

AFAIK fake engine noise is in all modes, it just gets dialed up in Sport+. But I thinking the bigger effect is the higher revving engine because of the more aggressive transmission shift points. Same with "S" transmission shift mode.

Adaptive shocks may help mute road impacts a bit, but IMO the biggest difference would be the more aggressive 20" sport tires on A-Spec. And don't neglect the stiffer rear springs.

Acoustic glass front side windows are unique to Advance, but all trims have an acoustic windshield. Whether there are any other differences, like additional noise dampening materials, Acura isn't saying.

 

Different rear springs on A-Spec. Look at the parts listings on oemacuraparts or elsewhere.

 

Wander, so in regards to a flatter ride while cornering, do the adaptive dampers also reduce the front end rising up and the rear squatting down when accelerating from a stop? Or when braking to a stop, do they help to keep the car level?

 

You’re right about traffic roundabouts. After reading your post, I’ve given the rotaries around my home the Sport+ treatment. What an exhilarating experience if nobody else is in the circle.

 

Or in the vehicle!

 

Get there around 4 AM on a rainy Tuesday morning when nobody is around and you've got your own skid pad.

😊

 

Rainy Tuesdays in Montana aren't very common, but it's a thought. I've tried some similar moves in vacant parking lots, and the capabilities of this combo are pretty impressive.
The dampers and the SH-AWD are both an integral part of the roundabout experience. As tempting as it is to glance down at that accelerometer thingy in the instrument cluster, this is a good time to exercise prudence and keep your eyes out for pedestrians/bikes/wheelchairs, etc.
I can't help noticing that many of the commenters on this subject are of the boomer class. Maybe we're on to something.

 

I do not have all the technical data on the RDX adaptive suspension. I do, however, have much technical data on the Delphi version of these types of dampeners as I did all the training on them at GM for my part of the country when they were installed on the new C-5 Corvette some years back. Reading the description on the functioning of the Acura struts/shocks they sound similar to how the Delphi version worked. First, a shock dampens by running a fluid through an orifice, that is a precision sized hole. To change dampening on a convention shock we just make the oil a difference viscosity or make the hole a different size. Many years ago car makers introduced variable dampening shocks. One way to do this used an electric motor inside the shock that would move a rod in and out and change the size of the orifice opening thus changing the rate of oil flow making the shock more or less "stiff" when the suspension moved. Some of you may remember seeing these some years back on certain Japanese vehicles. They were easy to spot as they had a wiring plug on top of the strut rod so that the computers could send commands to the internal motor used to change that opening. Technology improved and a later version of these adjustable shocks were developed at Delco, a division of General Motors (now Delphi) , and these were an improvement. Technology had advanced and now these shocks use magnetorheological fluid. A big word but its a synthetic oil with micro sized magnetic particles (fine pieces of iron) that will cause the fluid to thicken, increasing dampening, when a magnetic field is placed around them. This improvement had no moving parts to wear as the older designs did. Also the reaction speed was improved, no small moving parts to wear out and extremely accurate and very fast to adjust. The vehicle used sensors to determine speed, acceleration (and deceleration) body lean, throttle and brake action, etc. to adjust the shocks. For example, if you hit the brakes the front shocks could be stiffened to reduce nose "dive". The same was true for sudden acceleration, the rear shocks could be quickly stiffened to reduce "squat".(Dive and squat were a big deal on a very powerful car like the Corvette that got driven hard by many drivers). These systems performed well. I use to do a demonstration in class where I would use the GM scan tool to control the shocks. I would make them "soft", have the students bounce the car then I would suddenly stiffen the shocks. The effect amazed them as the car would suddenly just stiffen up when I hit the button. Then, just as quickly, I could make it "soft" again in a flash. (Which is a few microseconds if you are keeping track of details). So, I can tell you these shocks are amazing. Of course it all depends on the programing Acura did on these as to what functions they programmed in and how good a job they did on the software and sensors. I can tell you when I got my new RDX I really wanted the model with the adaptive suspension due to my working with these systems in the past and knowing how well then can improve the handling and feel of the vehicle.

 

Thank you for this excellent explanation, hans471! It must be great to have so much knowledge about the inner workings of vehicles, and the major auto manufacturers! I always wondered (but not enough to research it) what magnetorheological really means! I guess I figured I wouldn't understand, but you made it very easy! Amazing stuff.

Thing is, as an Advance owner, I can't tell how the same suspension would feel without the adaptive dampers...or when they do "adapt". It is a shame that Acura doesn't let the owners/prospective owners know this.

 

Gotta say thanks for sharing.

I would like to add a few comments:
- Adaptive dampers, though sounds great in theory, its effect varies a lot per application.
- Why? Because the most important thing about dampers is it's consistency. Imaging a car that is going into a bumpy corner, and all of a sudden the adaptive dampers turn soft because the system senses the bumpiness.... this is exaggerating, but tells you the tuning of adaptive system is not without limitation.
- The metrics of adaptiveness is not only how wide the damping force can change, but also how fast the force can be changed and how precise you can control the damping force. The faster, obviously the better, because it gives you more control to shape the suspension response to your target.
- The control unit also is key. The processing speed is one thing, and the amount of sensor data also matters.
- Magnetic system (for example the one on NSX) really execels in the three factors mentioned above, besides it can easily compensate temperature to provide consistent damping force across a wide range of scenarios. But it is also super expensive. RDX must have valve-based system.
- The limitation of valve-based system is the damping force can only change so fast. Also, the damping change is not fully linear throughout the adjustable range. So the tuning tends to be conservative, and the damping force does not change greatly for consistency.
- Even though the control unit can adjust 500 times/second, no one really does that on a valve-based system. The higher sampling rate basically gives the computer a better chance to figure out what is really happening, so it can make proper adjustment.

 

All good points. The latest adaptive systems with the magnetorheological fluid are amazingly fast. Its been said that on a good system they can detect when a wheel is going into a pothole and adjust before the wheel hits the other side of the hole. I can not verify that with data but having worked with them I can believe it. As for when they make changes, they are pretty amazing also. It is difficult, if at all possible, for an average human to be able to pick up the moment of change. I know on my Advance I never notice a change but when driving on tight, twisty roads I just know the car handles so well and I don't get body lean. I never notice a change from soft to harsh or back, I just know the car seems to always handle well but without a stiff harsh ride but with an excellent "feel". That is the mark of a good system, its so transparent you don't know its there. This is why I would do a hands on demo in the class as driving the students never noticed the change. When I went into the system and forced the change then they were surprised. The variable steering effort (speed sensitive steering) was the same way, transparent until you commanded the change.
As for the systems, the magnetically controlled systems are much faster and more reliable than the older mechanical valves.

I can not tell a lie.....I grew up fascinated by the technology of machines, engines and vehicles. I loved the physics and math of it and my career in the automotive world was just a fun ride. Being on the cutting edge and working on the "inside" with some of the smartest people one could ever want to be around was just a joy.

A very good article on the operation and application of these systems:

How it works

 

The downside to the magnetorheological systems is they are more expensive. Most manufacturers use systems like the RDX has, where the shock absorber is a conventional oleo-pneumatic design but with externally adjustable valves. Aside from Acura, Nissan and BMW use these in their "sportier" options packages. I do wish the Acura system offered the option for even more softness; my part of town has bad roads. The suspension travel in the RDX is hindered a bit by the fact that it is not a double-wishbone design; the new TLX and MDX changes that.

Higher end luxury cars and SUVs, i.e. Range Rover, use self-leveling air spring systems which give super soft rides but roll more in the corners and are more maintenance intensive.

The ultimate adjustable suspension used most McLaren sports cars (and is an option on the Mercedes S class) are fully active hydraulic systems. These replace the passive shock absorber with a hydraulic cylinder that is independently moved up and down for each wheel to keep the car level and all four wheels in continuous contact with the road surface. The hydraulics also eliminate the anti-roll bars. Replacing one of these, on say a McLaren MP4-12C, will set you back about 12k.