4.2Q Self Levelling Rear Suspension ...

[RoscoNZ]

As many 4.2Q A8/S8 fans will know, the A8 was supplied with optional self levellign suspension ... I think all NZ new models were specified this way .. but 3.7V8 & 2.8V6 imports may not have it ...

The rear shocks have a 15 bar pressuried Gas over Oil screw on reservoir with a stretchy membrane across the middle of it. Over time the gas pressure drops away and the shock control drops away badly .. especially noticeable on rebound on the open road. These things are in the order of $900 each and Conti's / Gintraps state that repair is by replacement .. frankly bollocks to that.

After investigation I decided I would try and get mine repaired - I got the Bilstein agent in Penrose to take a look. These things unscrew easily and any remaining oil dropped out, a hole can be drilled in the back of it and a schroder valve screwed in allowing 15 bar of pressure to be applied. The membrane stretches and a plastic plug pops out the screw hole .. which incedently is how you buy them from the Stealer. When screwed back onto the shock housing, the plug is pushed back a little by the thread. Finally when the car is started and hydraulic pump pressure applied (same as steering system I think), the pressure pushes back against the membrane, further pressurising it.

Replace the wheel arch guards and your done. In the end a very simple and effective repair for a fraction of the Stealer part rip off prices. Not more than an hour or 2 labour and a few parts .. in the end I think he wwas struggling to make up the invoice to the $300 or so quoted. Great WIN / WIN. And if in future you need to repressurise, drop the liners and apply the Nitrogen to the valve in-situ .. too easy.

I think the reason these things cost a bomb is because they are technically dangerous goods being at pressure and the freight must be huge .. so save yourself a bundle and get it done locally. DOn't leave it too long ... previous experience on a '95 A8 was without any Nitrogen pressure, the membrane had completely collapsed ... then your done for ... Car has done 10k's on revised suspension and is an altogether new car ...

[BB]

Good stuff

[BOON250]

Actually the way you buy them from the stealer is as a complete unit... yes that is expensive but if thats the way its supplied ex factory its hardly the fault of the "stealer" is it??

[Neil_Corrado]

While thats great that you've found an economic way to repair them, the price isn't out of line with other manufactures with self leveling suspension. If people buy A8's thinking they are a good deal, then they are generally, sadly mistaken, anything major on A8/A8Q is expensive. If you read any period magazines on A8 at launch, Audi sold them under cost (although they didn't say so directly) to get market share, as the ASF was very expensive until the technology became more main stream.

[SteveC]

re-pressurising dead suspension spheres has always been a Citroen practice,

they use a nitrogen "spring" separated from the suspension fluid by a membrane, varying the amount of fluid between the activating piston and the "spring" adjusts the ride height leaving the (rising) rate of the spring unchanged

it's a pretty smart system

[CasuaL]

I just chucked some airbags in ! lol , sorted