Echoing JohnEnglish... I think. I personally don't believe people's problem with the B9 (2018-2019) DRC is a software thing. There are people on here who know the DRC system better than I do but I think it's basically a mechanical system. I'm not sure if/what programming is there or what difference it makes. The three settings in MMI (and there are three), Comfort, Auto and Dynamic have to do with valving in the dampers (shocks). Auto is more of a "balanced" or mid-point valve setting. There's nothing automatic about it.
My guess, after hearing discussion that upping oil pressure improves things, is that may be the difference between the pre and post facelift cars. Unfortunately, it seems difficult to find someone who knows and can service these systems. Save for dealers, maybe. And if you do get a dealer who will work on DRC, I think they'll stick to factory spec and are probably going to be unwilling to up pressure for fear that premature system failure could be traced back to and blamed on them. Even if it is true and the B9.5 has a higher pressure charge.
Thinking about how this system works, it makes some sense that increasing oil pressure would help. I'm pretty sure that the DRC system interconnects dampers through a central valve from corner to corner. My understanding is that there would be a fair amount of oil traveling through the system. This would require a fair amount of lines and distance for the oil to travel. The lines are small, at least compared to the volume within the dampers. So significant pressure would be necessary for an effective volume of oil to flow through the system and do so quickly enough.
I'm going to float a theory. I'm also a Jeep guy. I've had both Fox and Bilstein shocks on my 2020 lifted Wrangler Rubicon. Both sets of shocks are remote-reservoir. The reservoirs are connected to the main shock body with a hose that is varying degrees smaller than the reservoir or shock body. So in the reservoir, there is an internal floating/dividing piston. On the shock-side of the divider/piston is shock oil. On the opposite side is a Nitrogen charge of +/- 200 PSI. The Nitrogen charge pressurizes oil in the reservoir through the smaller diameter hose and into the main body to control cavitation, etc. While the Bilsteins are bypass shocks which change thing, the Fox are dual-speed adjustable and the user adjustment happens at the base valve which is at the inlet of the reservoir. So if you look at how the Fox work, it seems like there would be some basic similarities in terms of the concepts that loosely translate to the pressurization in the DRC system. Too little Nitrogen pressure and the Fox shocks soften. They can also suffer from the effects of cavitation. When the DRC system starts to wear and leak, it also cavitates which I believe is when people start to hear clunking from the dampers. FWIW, 18 Bar = 261 PSI.
I'm not sure B9.5 people would say that the DRC in their cars is perfect. But most say it's better, including some on here who've owned both versions. So, I wouldn't think that upping the pressure in the system would completely solve the problem. But I buy that it's a noticeable improvement.
Then there's the fact that working on the DRC system is going to be expensive. I have a B9 with DRC. I've never loved it. I bought it stock. I first tried MSS HAS and that didn't work well. I went to ABT HAS and it is better. But importantly, it's a Band-Aid, not a fix. I've lived with the car with ABT HAS for a couple years. It's livable, not great. I actually just finally pulled the trigger on Bilstein EVO T1 coilovers. They'll likely go on next week. I'll be into the whole system for under $5K, installed. I think it's highly likely that a dealer would charge handsomely to work on the DRC system and that after, it'd still be flawed. I think the Comp cars going to the KW v4 based system is Audi's acknowledgment that the DRC system leaves something to be desired. So, for people who dislike DRC, I think the solutions is to go away from it.
The reason for pulling the trigger now is, I drove a Comp car a few weeks back and loved it. It was lightly used and I have a feeling whoever had it before, adjusted it to be a little more docile for daily use. It was basically better in every way, than my car. I first thought I'd source the OE Comp suspension and after some deliberation just recognize that $12K+ in parts is too much to spend on a 7 year old car. I'd been researching this for years. Basically since I put the ABT HAS system in. I even ordered the EVO kit a year ago but I waited 6-8 weeks with no sign it was going to ship and cancelled. This time, I was lucky enough to find someone on here who is running and loves it. He also told me where to go to get a kit quickly. It worked and it's now sitting in my garage waiting to be installed. I'll update on here after I get the Bilstein kit installed.
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Originally Posted by TJUNER_RS4
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