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      01-02-2009, 01:01 PM   #1
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Active suspension - how does it work?

Does anyone know how the active suspenion technically works? How is the resistance of the dampers altered in milliseconds?
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      01-02-2009, 09:59 PM   #2
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I would like to know this as well
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      01-02-2009, 11:47 PM   #3
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no one knows?
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      01-03-2009, 12:24 AM   #4
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Electronic Damper Control (EDC).

Electronic Damper Control (EDC) reduces variations in wheel load, ensures tyres have excellent traction and counteracts bodyshell movement regardless of the weight your automobile may be carrying - and regardless of the state of the road's surface. EDC can even help shorten braking distances, meaning you enjoy outstanding comfort along with the best in BMW on-road safety.

Sensitive sensors constantly monitor all factors influencing the vehicle's behaviour and occupants’ comfort, including road conditions, load changes and vehicle speed. In a fraction of a second, the signals are analysed by the EDC microprocessor and orders are sent to the actuators on the shock absorbers, which, with the help of magnetic valves, are variably adjusted to provide optimal suspension.
Thanks to Electronic Damper Control, the tendency for the nose to dip when braking is practically eliminated. The influence of potholes and unevenness on the road surface is reduced to minimum. Whether you're behind the wheel or relaxing in the rear of the cabin, EDC delivers a remarkably smooth and comfortable ride.
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      01-03-2009, 12:45 AM   #5
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mind you, I am indulging in RBV (red bull and vodka). you can read my paraphrasing below or read the actual article by googling electronic or magnetic shock absorbers

it all starts with the ecu. the vehicle has accelerometers located in several places that send data to the ecu in regards to up and down movements of the car. this, in conjuction with vehicular speed, steering angle and possibly other data is analyzed by the ecu which in turn alters the dampening rates of the shocks. less than 10 milliseconds is required for a system response. the sport setting is a control map that makes all adjustments, including the beginning threshold, more stiff , or a higher threshold for shock movement, or technically a lower flow rate of hydraulic fluid.

a lower threshold, i.e. comfort setting, the more fluid can flow, allowing the shock to posess longer travel, or less dampening effect.
this physically happens by way of a motor altering the size of the hydraulic channel.

the magnetic systems in use utilize metallic particles in the fluid, when these systems are actuated, an electric current (up to 5 amps per corner) causes the metallic fluid to become more viscous and thereby limiting the flow through the orifice. these operate 1/1000 of a second or
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      01-03-2009, 03:38 AM   #6
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Quote:
Originally Posted by gemini330zhp View Post
In a fraction of a second, ....... orders are sent to the actuators on the shock absorbers, which, with the help of magnetic valves, are variably adjusted to provide optimal suspension.
Thanks for the info (sounds like an advertisment / press release?). Anyway, I was sctually looking for info on how the flow in the actuators is varied, and this is basically answered by "the help of magnetic valves". Didn't know that magnetic valves have responce times of milliseconds - they must be pretty high tech (super fast & very precise)...

Quote:
Originally Posted by ssemerod View Post
a lower threshold, i.e. comfort setting, the more fluid can flow, allowing the shock to posess longer travel, or less dampening effect.
this physically happens by way of a motor altering the size of the hydraulic channel.

the magnetic systems in use utilize metallic particles in the fluid, when these systems are actuated, an electric current (up to 5 amps per corner) causes the metallic fluid to become more viscous and thereby limiting the flow through the orifice. these operate 1/1000 of a second or
Thanks. Here we have (a) a motor altering the size of the hydraulic channel (or the crossection of an orifice maybe?), and/or (b) a magnetic system embodying variable viscosity fluid. (b) sounds pretty impressive (star trek technology?), but which of they two is it? Or is it a combination of both?

BTW, what happened to you in the end? RBV kicked in suddenly, wife / gf stepped in?
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      01-03-2009, 05:13 AM   #7
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fuck all these technical explanations makes it feel like Star Wars!!
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      01-03-2009, 05:20 AM   #8
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It's not a true active suspension, like lotus experimented with in the past where it would increase the hydrolic pressure depending on what the car is doing. Those cars had NO LEAN when turning.
MB's system is a semiactive system, where the small bounces are handled by the springs, but larger motions, like body roll are handled by changing the pressure in the struts.
I believe the EDC just varies the valving depending on the road and style of driving.
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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
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      01-03-2009, 05:53 AM   #9
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Quote:
Originally Posted by aus View Post
I believe the EDC just varies the valving depending on the road and style of driving.
must be very quick & precise valves...
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      01-03-2009, 11:34 AM   #10
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Quote:
Originally Posted by gr8000 View Post
must be very quick & precise valves...
The GM/Ferrari shocks have tiny metal particles suspended in the fluid and the system is able to vary the thickness of the fluid by changing the charge through the fluid. It's pretty slick. I believe the EDC is a valve based system though.
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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
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      01-03-2009, 11:37 AM   #11
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Where there any problems with EDC in the past?
The M5 and M6 have them too, right?

Audi uses DRC (Dynamic Ride Control) which is great (especially on the RS4) if it works. (there were some problems with leaking shocks)
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      01-04-2009, 08:54 AM   #12
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Quote:
Originally Posted by aus View Post
The GM/Ferrari shocks have tiny metal particles suspended in the fluid and the system is able to vary the thickness of the fluid by changing the charge through the fluid. It's pretty slick. I believe the EDC is a valve based system though.
Exactly. The GM/Ferrari system uses a "magneto-rheological fluid" which operates like ssemerod explained a few posts up. BMW's operates by changing the valving/orifices.
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      01-04-2009, 05:15 PM   #13
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Quote:
Originally Posted by ssemerod View Post
mind you, I am indulging in RBV (red bull and vodka). you can read my paraphrasing below or read the actual article by googling electronic or magnetic shock absorbers

it all starts with the ecu. the vehicle has accelerometers located in several places that send data to the ecu in regards to up and down movements of the car. this, in conjuction with vehicular speed, steering angle and possibly other data is analyzed by the ecu which in turn alters the dampening rates of the shocks. less than 10 milliseconds is required for a system response. the sport setting is a control map that makes all adjustments, including the beginning threshold, more stiff , or a higher threshold for shock movement, or technically a lower flow rate of hydraulic fluid.

a lower threshold, i.e. comfort setting, the more fluid can flow, allowing the shock to posess longer travel, or less dampening effect.
this physically happens by way of a motor altering the size of the hydraulic channel.

the magnetic systems in use utilize metallic particles in the fluid, when these systems are actuated, an electric current (up to 5 amps per corner) causes the metallic fluid to become more viscous and thereby limiting the flow through the orifice. these operate 1/1000 of a second or
There have been many discussions to this and in fact the consensus among everyone is that COMFORT and SPORT modes are static modes where the shocks are set to a certain level and left alone while NORMAL mode is the active mode where the system will make constant adjustments, leading to some times the suspension being stiffer than when in SPORT mode. It is claimed that the best times are achieved in the NORMAL/Active mode.

Hope that helps.

Cheers,
e46e92
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      01-04-2009, 10:15 PM   #14
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Quote:
Originally Posted by e46e92love View Post
There have been many discussions to this and in fact the consensus among everyone is that COMFORT and SPORT modes are static modes where the shocks are set to a certain level and left alone while NORMAL mode is the active mode where the system will make constant adjustments, leading to some times the suspension being stiffer than when in SPORT mode. It is claimed that the best times are achieved in the NORMAL/Active mode.

Hope that helps.

Cheers,
e46e92
Actually, the COMFORT mode is dynamic as well.
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      01-05-2009, 06:45 AM   #15
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Quote:
Originally Posted by Ronin13 View Post
Actually, the COMFORT mode is dynamic as well.
Quote:
Originally Posted by e46e92love View Post
There have been many discussions to this and in fact the consensus among everyone is that COMFORT and SPORT modes are static modes where the shocks are set to a certain level and left alone while NORMAL mode is the active mode where the system will make constant adjustments, leading to some times the suspension being stiffer than when in SPORT mode. It is claimed that the best times are achieved in the NORMAL/Active mode.

Hope that helps.

Cheers,
e46e92
I thought I read in this forum that active suspension is on comfort & normal settings (i.e. only the sport is static). Are you sure?
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      01-05-2009, 09:20 AM   #16
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Quote:
Originally Posted by gr8000 View Post
I thought I read in this forum that active suspension is on comfort & normal settings (i.e. only the sport is static). Are you sure?
I'm pretty sure, hence why NORMAL is the preferred mode for most. But hey, I could be wrong, spent most of my life being wrong, so who knows....

Cheers,
e46e92
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      01-05-2009, 11:15 AM   #17
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Both COMFORT and NORMAL are active suspension modes, only SPORT mode is passive (set at 75% of maximum damping).


Best regards, south
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      01-05-2009, 11:20 AM   #18
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Quote:
Originally Posted by southlight View Post
Both COMFORT and NORMAL are active suspension modes, only SPORT mode is passive (set at 75% of maximum damping).


Best regards, south
Like I said, I spent most of my life being wrong.....Thanks for the clarification south.

Cheers,
e46e92
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      01-05-2009, 11:33 AM   #19
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Quote:
Originally Posted by e46e92love View Post
Like I said, I spent most of my life being wrong.....
Really? That's interesting - you must be a millionaire then, eh?
Okay, give me 42 numbers for the lottery & I will choose the remaining 6 - then we share the gains!!!
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      12-04-2013, 12:23 PM   #20
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Reviving an old thread...

How quickly does it change from say comfort to normal after you hit the button?
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      12-04-2013, 01:30 PM   #21
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Quote:
Originally Posted by aus View Post

The GM/Ferrari shocks have tiny metal particles suspended in the fluid and the system is able to vary the thickness of the fluid by changing the charge through the fluid. It's pretty slick.
This, the same company apparently makes all systems. I talked to a rep from the company, and when a magnetic field is applied it increases the viscosity to make the fluid flow more slowly. This stiffens the suspension, and can reduce nose dive when brakes are applied, body roll, etc.

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      12-04-2013, 01:59 PM   #22
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There is missing/incorrect information in this thread, so allow me to set the record straight:

Cars without Competition Package (ZCP):
-comfort is dynamic
-normal is dynamic
-sport is static


Cars WITH Competition Package (ZCP):
-comfort is dynamic
-normal is dynamic
-sport is dynamic



Some drivers do not like the stiffer ride settings and feel it is too artificial since it isn't providing them the right amount of feedback. A few tests showed that lap times in the different modes were not vastly different. The purists shy away from it entirely.

My advice is to use comfort for your street driving (unless you like having your teeth rattled out), and to experiment with the three settings when on the track. It's quite subjective in many ways.
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