DRC Front shocks ???

[Ricky]

I wager the knocking from the rear is the DRC control valve and that your pressure is down. Exact symptoms I had second time around. First time was knocking from the front.

Out of interest, what causes the knocking if all four dampers are new ??? Is it just down to the pressure control which when damaged lets pressure out ?? I’m not sure if I’m just imagining things but it just doesn’t feel or sound right.

I'm not sure this will help much but thought I would share anyway ! This is the exact answer I got back from Audi Uk when I was having DRC issues albeit with my RS4 not an RS6 !!!!!

Our Technical Team has now concluded that the noise you are complaining of is an unavoidable concept related DRC system noise. This is normal DRC operational noise caused when the shock drops after going over a speed bump, pot hole etc.”

These are three of the many questions I asked them with their associated answers :


1. Could it please be explained to me technically / mechanically with the aid of an exploded diagram, what actually causes this DRC knock ?

Schematic is not available however, the Audi factory have advised the noises are system related and are caused by a quick reduction of the oil pressure in the central valve during the shock absorber movement.
The noises are transmitted from the central valve via the pipes to the shock absorber.
A too low oil pressure in the system can increase the noises. As a result of diffusion and running-in air can gather in the system, this reduces the system pressure.
For the full operation of the DRC system a pressure of 20 bar in the individual cycles is required.

This link will demonstrate the DRC system http://www.audi-technology-portal.de/en ... control_en


2. An individual from my Audi dealership told me he had spoken to the head technical guy from Audi Uk and he told him that even if the shocks were fitted and the noise went away, it would come back again at some point in time and I would be unhappy at some other stage on down the road. Please explain technically to me why this noise would come back if it disappeared by replacing the shocks ?

As we were not party to this particular conversation we can only reiterate at this point that there would be no benefit to replacing the shock absorbers as the noise is operational.

3.Why am I being treated differently to other customers ? There are countless individuals on forums who have had shocks replaced for the exact same DRC fault as I have reported ?

Whilst we acknowledge that customers discuss in detail, events surrounding their vehicles on numerous forums, VWG do not support or endorse any such forum activity and every customer who is in contact with Audi UK is treated as an individual


I fought and fought, but in the end they simply refused to replace anything on the car. How do you ever get any further with a matter like this when Audi Uk are giving you these answers, whilst countless individuals are getting their shocks replaced hand over fist. We all know this has been a wide spread problem. So much so that on my B7 car, because of the masses complaining, Audi provided a 5 year warranty as a goodwill gesture with the replacement shocks, yet the exact same fault years later has now become an 'unavoidable characteristic', or an 'operational noise'. Talk about trying to distance themselves from the problem !!!


Much and all as I still wouldn't like it, I could accept that fact if everyone got the same answer, but that's clearly not happening ! A lot must really depend on the actual dealer. Cant imagine Audi UK wavering from the stance they took with me, if a dealer were to forward a case to them.

[harrier]

I feel for all you guys who are having trouble !!!!!

I'm pretty much fed up with the whole DRC thing ! Audi have been having problems with them for a seriously long time.

Both my RS4's had DRC problems. The first B7 RS4 they eventually fixed, but when it came to my brand new B8 RS4 I was simply told by Audi UK, it 'was a characteristic of the car and within tolerance'. Bull <beep> !!!!! They simply refused to do anything about it and there was only 50 miles on the clock when they were informed of the problem. I simply couldn't put up with the knocks and bangs from both front shocks so in the end, I ended up selling the car. The dealer in question even re-pressurised the shocks and guess what, they managed to make the problem worse. Some dealers are just incapable of looking after these RS cars !

I would love an RS6 but Audi's refusal to help with my RS4 has put me off purchasing another. Thats a real shame as I love these RS cars. I have been keeping an eye out for an RS6 with ordinary air suspension and finding one seems to be extremely difficult as most seem to spec theirs cars with DRC.

Ricky !

Where about in the country are you Ricky, as I can recommend a dealership who have looked after my Audi's very well for nearly 18 years now and have a chief technician who loves the RS cars and really knows his stuff.

[Ricky]

Where about in the country are you Ricky, as I can recommend a dealership who have looked after my Audi's very well for nearly 18 years now and have a chief technician who loves the RS cars and really knows his stuff.
[/quote]

Unfortunately on the other side of the water from you in Northern Ireland mate, and we dont have a choice of dealers over here. Same dealer in two different locations.

[innercry666]

There is a TPI on this that defined that if the knocking noise is heard on a test drive then the front shocks should be replaced for modified versions that are available. I had mine replaced a couple of years and the ride quality improved to as the car was when new.

There was something that stood out to me in their response though that may be an avenue of exploration with them:

"too low oil pressure in the system can increase the noises. As a result of diffusion and running-in air can gather in the system, this reduces the system pressure.
For the full operation of the DRC system a pressure of 20 bar in the individual cycles is required".

I would be asking the following questions:
-Exactly how does air gather if it is a sealed system?
-Is it possible for a reduction in pressure to damage the central valve or shocks?
-What is Audi's lowest acceptable pressure for the system?
-What happens to the ride quality if the pressure reduces?

I used to find that if the pressure was low in mine it was noticeable as the ride quality suffered. Audi increased the pressure back to 20 bar again a couple of times and it would improve. I can only assume they had to add fluid back into the system and the pressurise it to 20bar before resealing.

Shame that you are getting push back when loads of other owners with the same symptoms have had their shocks replaced. I wouldn't say the new ones were perfect but they seem to go longer before needing the pressure increasing again.

I'm having similar issues with Audi with the RS6. They don't want to know about DRC issues. They say they have checked for faults in the control unit and it is fine despite my protests saying the ride quality has deteriorated and can they check the pressure. I've asked them to actually check the pressure next time...

[Daveperc]

Having had 11 years running my C5 Beast on DRC (mostly very happily) a few questions and observations?

- Is the static system pressure monitored and available through MMI or VCDS? Frankly the lack of a ready measurement was always the Achilles heal. For the C5 I designed, but sadly never implemented, a simple system incorporating two pressure gauges into the two halves of the system, to be mounted in the battery well close to the pressure vessel. With the car at rest the static pressure on the system could be read and a need for repressurisation recognised.

- On my C5 I uprated the ARB's, firstly to improve handling, but also to reduce the loads on DRC. I believe this contributed significantly to the reliability I had. Is an ARB upgrade available for the C7? I haven't checked, or felt the need to so far!

- On the C5 there was a real knack to getting the pressurisation right, which very few techicians or dealers ever seemed to get right. The almost singular exception was Stuart Hunt at Camberley, who is now at Audi Taunton. My system was maintained by him, and once we got the V3 components on there it ran faultlessly for over 100K miles. It can be done, but only by really experienced techs.

I appeciate that doen't particularly address the OP problem, but the point about the experience of the techs may well explain the different responses people are getting.

When it works DRC is great - when it doesn't it's horrible!

Dave

[innercry666]

Hi Dave,

When you mentioned there seems to be a knack to getting the DRC pressurised correctly do you know specifically what the issues were?

I don't know about ARBs for the RS6 but I can see that providing stronger bars could help reduce the lateral loads on the DRC and hence help it out. I'm not aware that the pressures are available via VCDS however I can see that would be really useful as well!

[Daveperc]

there seems to be a knack to getting the DRC pressurised correctly do you know specifically what the issues were?

Not in detail I'm afraid as I simply trusted Stuart to get it right! AFAIK it was to do with removing the tool at the end of pressurisation without letting any fluid escape so it didn't lose pressure. If you need more info possibly the best bet would be to give MRC a call as they now offer the service for the C5.

A pressure reading via VCDS would really be the best way forward so that that a reading can be checked after any work on the system.

Dave