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Discussion Starter #1 (Edited)
Here's a little overview of the "formula" for the soft-to-rigid settings for the electronic suspension on the "S", "Q" and "Q4" cars. My starting point for the information was the German version of the workshop manual, the one that provides those nice graphs for the parameters of the various sensors.

Soft-to-Rigid formula of Alfa CDS suspension system

primary system prerequisite: active working struts (shorted or open circuit will cause system to switch to rigid illuminating red fault light)

primary sensors: brake pressure, 1-2 gear + throttle, accelerometer (vertical movement), steering angle, steering rotational speed

secondary sensor: speed
(if speed data is not available system will switch to rigid without illuminating red fault red)
-------

brake: constant all times, all speeds, switches to rigid with ≥ 20 bar pressure applied to brake pedal

1-2 gear + throttle: conditional, switches to rigid from 2.5 mph to 31 mph when throttle sensor is ≥ 20° open and 1st or 2nd gears are selected

accelerometer: constant all times, all speeds, switches to rigid with .2g of vertical force

steering angle: conditional and relational vis-a-vis speed, for example switches to rigid with ...

180° rotation @ 20 mph
81° rotation @ 31 mph
54° rotation @ 40 mph
27° rotation @ 49 mph
18° rotation @ 55 mph
9° rotation @ 68 mph to 140 mph

steering rotational speed: conditional and relational vis-a-vis speed, for example switches to rigid with...

100° per second (= 25° per 1/4 sec) @ 31 mph
72° per second (= 18° per 1/4 sec) @ 40 mph
48° per second (= 12° per 1/4 sec) @ 50 mph
33° per second (= 8.25° per 1/4 sec) @ 68 mph
30° per second (= 7.5° per 1/4 sec) @ 74 mph
5° per second (= 1.25° per 1/4 sec) @ 93 mph to 140 mph


speed: switches to rigid between 0 mph and 2.5 mph; serves as secondary parameter for all other sensors except brake and accelerometer

Some additional comments taken from BB posts:

I've also tried the same run with the CDS in both SPORT and AUTO settings and I don't think the AUTO setting slowed me down any. It does a pretty good job of soaking up the undulations actually and I've grown to like it although sometimes over certain types of bumps the back end does feel a little loose for a split second or two. (kcabpilot)


There was once a post of Helli from Bavaria (Q4) showing this great curve in the Austrian alps, a big descent followed by a sharp curve, and I wondered if I would have the guts to floor it and power it around the curve in "auto". I myself tend to use "auto" for some roads, and "sport" for others. But you are right on regarding the "soaking up of undulations", I experienced this when I had a bent rim, when on "sport" you felt a constant throbbing-pulsing, and when on "auto" it was imperceptible. (pinino)


The quality of the CDS “soft” setting is seldom mentioned. It’s an experience unlike any conventional spring-strut system. Your words "soaking up the undulations" is right on, “Mr. T” aptly described it as a “floating” quality; one might add it's similar to the feeling of lying on a water bed. Uninitiated guest passagers are always impressed. For long distance driving on boring roads it’s pure pleasure. The explanation of the effect lies in the way the by-pass holes located near the top of the bypass sleeve equalize the pressure between reservoir and inner tube pressure, all this while piston and foot valves still do their thing. (pinino)


I leave mine on sport the entire time. My father had a Buick, and I just didn't like that way too soft feeling. To me the auto setting feels the same in most cases. I think you lose some of the feel of the roads the tires are trying to tell you about. Not my idea of an Alfa, but then again, I am of the old school I guess. And, I discovered, when the car is in the sport setting most or all of the time, the suspension bushings don't wear out nearly as fast since they travel/distort less. (Del)


The Buick reference seems to be somewhat a mischaracterization. Does the Buick have a two-setting suspension system with a somewhat sophisticated ecu? You know, if you drive the S really hard in "auto" you are actually in "rigid" most of time. I was just curious if Paul experimented with his car in that way. (pinino)


Oh, I know that, but I prefer the taut feeling all of the time, even when I'm not hotdogging it. To me, the really soft up and down ride the auto setting gives me when just pooping around just brings back memories of the Buick. Sorry about that, just personal preference. Many people nowadays seem to prefer a softer more plushy boulevard ride than us sports car vintage drivers.
And, I have several roads I drive on where the auto setting doesn't keep the front spoiler from potentially scraping when the road suddenly rises in front of the car. The problem is that the vertical motion sensors are in the trunk, which doesn't see the effective downward motion of the nose. A flaw in my book. The sport setting prevents that problem every time.
(Del)


Must be the Pilot in me, I'm well accustomed to "floaty feel" but in regards to the CDS; well... SPORT mode is a mere push button away and the "sporty taut ride" certainly has it's place. Not so much drolling over miles of concrete freeway expansion joints however. The soft ride definitely has it's place as well in my book and I really like the versatility and the option of selecting it. As pinino pointed out newly initiated passengers are just flat out amazed by it. (kcabpilot)
 

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Thanks for the info.

Have to think that it seems too complicated just to provide a soft ride for some, lol. Easier to just leave it in Sport setting. At least it has always worked for us all these decades but that's just our opinions (my wife and myself). Also set the Konis on the LS to about the same setting as the S Sport setting, and we both think it has enhanced the LS.
 

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Discussion Starter #3
Del, you are one of the fortunate ones blessed with smooth roads.
 

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Well, they are not that smooth here, and have driven on pretty bad roads in many states with the cars, but maybe my big butt helps cushion those out, hah. NYC comes to mind as having some of the worst roads. Also drove old highway 99 south through the Central Valley in Cal, and nothing at all helped on that horrible road. Guess it is better now.

I did find that switching back and forth between the settings did not change the "jiggity" ride all that much as far as the sharp little "bumpings" are concerned, but did change the chassis swaying. The sharp little "bumpings" stayed about the same, that part of the ride being a function of the spring rates more than the shock settings, which control the larger suspension displacements. I did find that on some rough roads, the Auto setting did not do the job as just setting the button to Sport did, having the engine sump bottom out a few times (luckily not bad enough to do any damage) before I learned that.

The vertical motion sensors are in the back, don't protect/set the front suspension. I think that is why at least a few report sump impact and damage while using the auto setting. With the setting at Sport, sump guards are most likely not needed.

Just my impression, but I also think that having the setting on Sport all the time lets the rubber bushes in the suspension last longer, less suspension movement involved over the years of driving.

I guess we were just raised on relatively stiffly suspended foreign cars, both of us (I did a fair amount of autocrossing with the ones I owned), and we have always tended toward them as a matter of preference. From the old school.
 

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Here's a little overview of the "formula" for the soft-to-rigid settings for the electronic suspension on the "S", "Q" and "Q4" cars. My starting point for the information was the German version of the workshop manual, the one that provides those nice graphs for the parameters of the various sensors.

Soft-to-Rigid formula of Alfa CDS suspension system

primary system prerequisite: active working struts (shorted or open circuit will cause system to switch to rigid illuminating red fault light)

primary sensors: brake pressure, 1-2 gear + throttle, accelerometer (vertical movement), steering angle, steering rotational speed

secondary sensor: speed
(if speed data is not available system will switch to rigid without illuminating red fault red)
-------

brake: constant all times, all speeds, switches to rigid with ≥ 20 bar pressure applied to brake pedal

1-2 gear + throttle: conditional, switches to rigid from 2.5 mph to 31 mph when throttle sensor is ≥ 20° open and 1st or 2nd gears are selected

accelerometer: constant all times, all speeds, switches to rigid with .2g of vertical force

steering angle: conditional and relational vis-a-vis speed, for example switches to rigid with ...

180° rotation @ 20 mph
81° rotation @ 31 mph
54° rotation @ 40 mph
27° rotation @ 49 mph
18° rotation @ 55 mph
9° rotation @ 68 mph to 140 mph

steering rotational speed: conditional and relational vis-a-vis speed, for example switches to rigid with...

100° per second (= 25° per 1/4 sec) @ 31 mph
72° per second (= 18° per 1/4 sec) @ 40 mph
48° per second (= 12° per 1/4 sec) @ 50 mph
33° per second (= 8.25° per 1/4 sec) @ 68 mph
30° per second (= 7.5° per 1/4 sec) @ 74 mph
5° per second (= 1.25° per 1/4 sec) @ 93 mph to 140 mph


speed: switches to rigid between 0 mph and 2.5 mph; serves as secondary parameter for all other sensors except brake and accelerometer
Very nice info thanks for posting. So does the ECU switch ALL struts to rigid given activation by one of the parameters, or does it work with the accelerometer and individually actuate struts? It seems like it's more of an on/off thing rather than a distributed thing.
 

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Discussion Starter #6
"So does the ECU switch ALL struts to rigid given activation by one of the parameters, or does it work with the accelerometer and individually actuate struts? It seems like it's more of an on/off thing rather than a distributed thing."

It can be one of the parameters or a combination thereof (as noted), but when the threshold is met, the ECU switches all struts to rigid simultaneously.
 
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