AUDIHenry

Hi guys,

For those with adjustable ride height A8s, would you happen to know how exactly the air struts are setup? Are there bellows? Are there traditional shock absorbers?

I'm interested in the setup at the suspension level, not the whole system.

Pictures would be fantastic.

Cheers!

Mister Bally

As far as I know, they are strictly air struts. When the WABCO Ecas air compressor went bad (blew the 40 amp fuse, due to a bad pump motor) the ride immediately went to sheissen. There was no hydraulic cylinder doing any work in the air struts.

I have no pictures of the struts themselves, but the brochures that are archived somewhere on the website and Audiusa.com site show phantom views of the suspension system.

In my picture poster on this site I have several photos of the suspension leveling valves AKA height sensors. They are the last several photos archived there.

AUDIHenry

Thanks much, I think I understand it now!

MP4.2+6.0

<center><img src="http://pictureposter.audiworld.com/26081/front_shock.1.jpg"></center><p>
Here are some excerpts from a description from Audi's materials about the suspension:

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Each strut assembly has a twin-tube, gasfilled shock absorber with continuous electrical control. The main dampening valve in the piston is mechanically pretensioned by a spring. A solenoid is installed above the valve and the connecting cable is routed to the outside, through the hollow piston rod.

The dampening force is determined by the flow resistance of the valves. The greater the flow resistance for the oil flowing through the valves, the higher the dampening force.

The amount of magnetic force can be adjusted by changing the amount of electrical current. The higher the current, the lower the flow resistance and therefore, the dampening force. The highest dampening force is achieved when the solenoid is not electrically actuated. For the lowest dampening force, the solenoid must be receiving a current of approximately 1800 mA. In emergency running mode, the solenoid is not electrically actuated. In this way, the dampening force is set to maximum, ensuring a dynamically stable driving condition.

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There is a detailed service training publication on it if you get super interested in the details. You can get it via Bentley Publications and Dyment too as I recall.

Mister Bally

That does not seem to be what is in the D3 A8's as they have air struts made by Continental connected by plastic hoses to a WABCO electric air compressor. The ECU is also supplied by Continental to Audi.

I'm not sure but I believe the electrified hydraulic one you show is for the R8.

bac2h

What's going on in the 7th picture down in your pic poster???

Mister Bally

Rear brake pad replacement. I posted about the procedure that my 13 YO helper assisted me with. Seemed like more time on the PC than wrenching on the caliper. Per the Bentley manual the steps are necessary to back off the stepper motors used for the parking brake function Also note the dash display in photo 6.

MP4.2+6.0

The information is from publication 994303, Audi's self study program they use for service and other training. It was published in 2003, well before the R8, and is loaded with pictures front to back of nothing but the D3, including a D3 cutaway on the cover.

Here's some more text that tells you clearly it's the D3, which is just before the picture I included:

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Adaptive Air Suspension
Today, designing a chassis must overcome conflicting requirements.

A car designed to be very comfortable when driven at the limit, falls short in terms of driving safety. On the other hand, a car with exceptional sport tuning achieves considerably higher cornering speeds and reaches its limit much later, but is usually very limited in comfort. The equipment must deliver not only universal purposes such as function, safety, strength and durability, but also comfort, reduced weight and premium acoustics. To satisfy these contrary requirements, the 2004 Audi A8L is equipped with a new, fully load-bearing, Air Suspension System with electronic dampening control.

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There is also another one, called Chassis Systems SSP, number 997303, also specific to the D3, that has a lot of overlapoping material, also put out in 2003 as the car was being introduced.

To your post, I think you are mixing up two things, the air control and the electric control. The air control is the basic lowering and raising of the car. But remember it also needs computer control to tune the damping level based on the setting you choose in MMI (for example, think about "Comfort" and Automatic" that sit at the same ride height at low speeds but are at different levels of stiffness). Varying (increasing) the air would just jack the car up, not change the stiffness, that is not without some kind of electric/solenoid intervention to the valving at a minimum. Separately, no doubt about it, the electric connector in my car is plainly visible right there at the front struts from underneath. W12's have non sport air struts, which I confirmed by part number; they have sport roll bars (which I changed out to S8 level per my prior how to post). Thus my car on the air strut assembly is no different than any other non sport 2006 4.2.

Mister Bally

There you go, it is an air unit with electric dampening. Mine has the electrical connectors as well. I did not see any mention of air in the original post. Me bad!!!

Thanks for the information. It sure is a nice riding car, even on poor road surfaces.

Caltre9

Regarding the electronic damper control, could you take the gas filled strut out of the air suspension and run it through a coilspring and it still be an effective system for a 2005 a8l that had the airshocks removed and a strutmaster kit installed only the bilstein b6 struts in the kit keep snapping off at the threads due to the weight of the Car and no strut mount bushing?