DRC test results.. Final entry.. for now..

[Hy Octane]

Most of you know the issues we have been having with the DRC systems in our cars..
I have had mine repaired 3 times.. each time I wasnt satisfied mainly because the ride was softer than it had been since new.. thus my insistance that the repair was done improperly..

In order to finally get AoA to deal with this, I scheduled a meeting with Willie Castro, their main fixit guru, to meet myself and two other RS6 owners who have never had any DRC repairs done to theirs at Pacific Audi here in SoCal. Thanks to Benman and S42SKI who took time out of their busy workdays to meet us there, we now have a possible answer.

I was sure that when I drove Benmans car I would again feel the stiffness I have been missing. To my surprise, his car rode almost identically to mine now.. he says this is how its been since new..
We all went for test drives in each of the three cars.. Willie, Paras ( the tech at Pacific Audi) and Benman and Myself..
To my utter shock, all 3 RS6's were within miniscule parameters of each other.. in other words, they were all about the same..

So, how could this be? I know that my car used to be much stiffer than theirs before it was repaired.. I had to creep over speed bumps or any raised pavement, driveways etc..And it would appear that several others who had DRC repairs also felt their cars were now too soft..

The possible answer (and I hope Dr Aronis will chime in here) that we came up with is this:
The factory manual says that a proper functioning DRC should be between 12 and 16 bar.. anything under 12 bar and the DRC must be repaired..
It is our theory that when these parts are charged at the factory, some must be a little higher in pressure than others.. Annywhere between 12 and 16 bar is acceptable, but thats a large comfort zone .. If my car was at 14 or 15 bar before repair and now is at 12, this would explain the difference.. Why this happens we dont know.. perhaps the equipment here is not as good as the repair kit they use there.. who knows.. The deal is that indeed, my car used to have a higher pressurized DRC than it does now..but its still considered functional and not in need of repair..
Now that I know my car is not in danger of failing due to improper repair, I am ok with it.. I will keep it and continue to try and find a way to return it to its past form, but I am no longer going to crusade for this cause..
true, they should be able to return my car to its stiffer factory settings, but for now I am satisfied that its not abnormal as others are and have been satisfied with theirs since new..
It also crossed my mind that those of us who have had failures were also the ones who complained about the repair being too soft, while the ones with softer rides dont seem to have been affected by failures yet. Perhaps the shocks that failed did so because they were faulty from day one (ala a run of bad shocks?) and thus gave us this firmer ride..but eventually failed..
In any event, it appears that my DRC was the exception and not the norm..
I am now happy to report that for the first time since new, my RS6 is fully functional.
Perhaps I will pay out of pocket to try again someday, but for now, I plan to enjoy my car and finally get out of AoA's hair..for now.. hehe

Thanks again to Benman and S42SKI and everyone who has helped me with my problems..

Wanna race??


:addict:

[Benman]

Hey there Paul, any time buddy.:thumb:

Yeah, another thing Willie mentioned (and again, waiting for Aronis's thoughts on this) is that the failure occuring is likely at the higher bar tolerance. Afterall, it does make sense that someone with a 16 max bar setting is more likely to "blow a top" than someone at a more average 14bar or so... At least, it made sense to us.

So... I think it is possible that Paul's and Aronis's were all the way up at 16bar, the very max and "popped" down the road whereas mine "feels" according to Paul more like 14 or so. Very possible then why Paul's RS 6 feels only a little softer.

My thing though... If the range really is 12-16bar, that is a huge tolerance! I mean, from 12 to 16 is a 33% increase! Does anyone else find that odd?

Anyway, at least now your RS 6 feels "about" right and you can enjoy it.

Take care bud,

Ben:addict:

[s42ski]

Probably should have brought my camera - our three RS6's and one in the lot for sale ( no plates) at a relatively small dealership.

[Benman]

Originally posted by s42ski
Probably should have brought my camera - our three RS6's and one in the lot for sale ( no plates) at a relatively small dealership.

And all of our cars were different colors to boot. :D Was nice to meet ya' Steve.:thumb:

Speaking of plates, is it about time for me to put mine on? It'll be be three years in a couple weeks.;) :hahahehe:

Ben:addict:

[Aronis]

Interesting.

If you look back at my early posts I qualified all my posts by saying that the car did not seem as stiff as I recalled it being when new and certainly not as stiff as the S4 I compared it to at the dealer. This static comparison was one of the only ways I could articulate my car problem to the mechanic. They did not have an RS6 for comparison and when they ‘test’ drive the car they have no basis of comparison to know what the car should drive like.

I first noticed my car’s rear end bouncing on the broken ice on my road (and my 9 year old noticed too) and when I would pull into my garage the rear would bounce a few times over the slight step at the entrance. It was winter and I had not done any highway driving so I did not have the advantage of seeing the horrible highway speed ride that resulted from hitting a bump – I experienced that delight on the way to the dealer the first time!

After my first “repair” when I got home from the 3 hour drive from the dealer the front end was bouncing and as I drove into the garage the front rebounded a few times and then the rear end too. After some time I was able to piece together a rational explanation for this.

When the car was first diagnosed with a leak from both rear shocks from the seals, I asked the dealer and mechanic if it did not stand to reason that the front shocks seals would also need to be replaced. They said no, not seeing the logic of the same corrosion issue hitting all four seals. This was not ROAD salt but dissimilar metals causing electrolysis and the resulting corrosion. Yes maybe the road salt helped but that did not explain the same leak in California cars.

So when they did the first fix (replaced the seals and central valves) the car MAY INDEED HAVE BEEN BACK TO NORMAL!!!! But after sitting over night fully pressurized and after a few test drives I surmised that the front began to leak and leaked enough to soften the ride such that when I drove off it was back to being No Good. I could also hear a clunking in the rear which was first thought to be the ‘empty’ control valves, but this ended up being now damaged REAR shocks, as I doubt the control valves were empty of fluid just from an overnight leak. They thought that trapped air had settles in the top of the shocks and that was the cause of the loose ride. The rear shocks spent the most miles being driven EMPTY and the fronts certainly would have suffered the same fate. After the finally agreed to replace the rear shocks the clunk was gone, but after ONE LAST test run where the service guy just had to pull the trunk liner out and drop the rear seats (something the mechanic did not do), they caused the strap which I was using to hold my kids car seat in place to fall and that buckle created a NEW THUMP that they spent several days trying to diagnose. Then ended up venting and refilling the shocks TWICE and perhaps some pressure was lost, I don’t know. They did not see a leak from the front shocks. But after replacing the rear shocks they DID NOT AGAIN REPLACE THE CENTRAL VALVES, thus the ride still was not right.

After that second repair the car still did not drive correctly and I took it to the local Audi dealership in Binghamton where it was looked at by the Porsche mechanic. When he drove it he was just shaking his head saying ‘this is not right.’ He too could feel the rear end feel like it was going to come around on him as we went up an entrance ramp onto a highway (long gentle sweeping ramp). When he put the car on his lift he and I could see the leak from the front shocks. He declined to get involved and would not make a call to the Latham mechanic to report what he saw. At this point the front was now softer than the rear...and more of a concern one side had leaked more than the other (driver’s side front shock) and the car was now very VERY scary over bumps at speed.

After some more AOA calls, the agreed to replace the front shocks and seals, but I don’t think they changed the central control valves again. As it turns out you have to! The front’s leaked, the pressure dropped, and the central valves were now depressurized. So new front shocks and seals may have fixed the final leaks, but that did not return the car to normal.

The Final repair done in Cicero, New York, did the trick. They noticed one more leak, but basically what they did beside fixing that final leak was simply install new Central Control Valves as the last piece of a system which should have been fully replaced from the start – I was willing to pay for the GD shocks at the first repair in Latham!

So the frustration was from the crappy ride after the repair attempts and their inability to see the difference due to inexperience with the car and their inexperience fixing the DRC system.

Our complaints were hard to articulate to the dealer and I think we have been fixated on the static comparison of the car while pushing on the rear end! Again it was not our job as the customer to trouble shoot the car.

You have to distinguish the softness from the lack of damping.

A stiff suspension (stiff springs) can be moved more easily if the shocks are not present (or EMPTY OF HYDRAULIC FLUID). The amount you can move the suspension is dependant on the dynamic range of the springs (fixed points) and how heavy you are to push on the car! I’m 250 pounds and can push harder on a fender than a 180 pound guy, but if I compare a few cars, my RS6, an S4, my wife’s Subaru, my dad’s M5, I can come to a basis of comparison. The SPEED at which you can move the car is more dependent on the damping effect of the shock absorber as the shocks is supposed to resist rapid changes – i.e. absorb the shock, but the stiffness of the spring does play a roll. Together the effect of the empty shock and our perception that the car is not “Stiff Enough” we come up with a very poor measure of the proper state of the suspension and again the better measure is the seat-of-your-pants measure as you drive. Thus I did not bock at the suspension still being easy to move when I picked the car up, but rather was pissed by the horrible ride on the road, the bouncing etc.

Now the difference in ride height that some reported after the repair is CLEARLY easily measured and compared, no brainer. But I’d love to know what exactly caused that difference! Wouldn’t you?

Again from what I recalled the car did not seem as stiff as when new and I don't know how quickly a set of springs can 'soften' with miles and time. Somehow I still doubt that is much of a factor.

Our complaints to the dealer seemed to revolve around the perceived 'stiffness' that the car should have when in fact it was a dampening problem! Their problem was not having another RS6 to compare our cars too to say "See it's the same."

Prior to the last repair, the lack of dampening allowed me to close the trunk and watch the car rebound two or three times. Or push on the fender once deeply and watch it rebound two or three times.

When I saw the other RS6 on the lot and walked up to it, my jaw dropped as it was as loose or close to as loose as my car was! So finally with an RS6 comparison I was confused!

I was sent a Video by Benman which shows the state of his normal RS6 and clearly his car was much stiffer than mine.

Again, as stated, I just may not have been recalling it correctly and my ability to move the car like an old Ford, up and down, was the only "quick" test I could do. So what I was seeing was the under damped suspension due to a system with too little pressure in the Central Valve to provide resistance to the fluid movement in the system.

The question about where the pressure was set on each car is interesting.

I remain uncertain as to whether the pressure in the DRC would affect 'stiffness' as much as thought, where as the spring stiffness would be responsible for that stiff feel. But clearly the depressurized system with a loss of hydraulic fluid is going to degrade the damping ability of the shock and allow you to move the car up and down more easily and more rapidly with a few pushes.

I don't claim to understand the workings of the suspension fully, but have pieced enough information together to get an idea how the DRC adds to damping and creates a more variable damping and a larger dynamic range of damping than stand alone shocks can.
Now if the system has no trapped air and is low on fluid, and the central valve pressure in the AIR CHAMBER is low then the dampening ability of the system is going to be greatly decreased as the fluid can EASILY move to the central valve and compress that AIR space, thus allowing the volume in each shock to change quickly. So instead of the piston in the shock moving through a viscous fluid in a cylinder with fixed volume and geometry, that piston can move more quickly as the SHOCK FLUID moves OUT OF THE SHOCK and the shock volume/geometry gets smaller. Thus the net effect is that the Piston is Not Moving relative to the fluid, but merely moving WITH THE FLUID = so the damping is reduced greatly. Net effect = nice springs, no shocks and BOUNCE BOUNCE BOUNCE.

So as the pressure is returned to that normal range this is less of an issue and the system dampens properly. Thus at some reduced pressure point the ride is noticeably softer, especially to the push on the fender rebound test we all do!

It appears that the explanation why the S4 was stiffer than the RS6 is that the RS6 suspension allows for more of a dynamic range (providing a more cushy ride) but still allows for spirited driving with a bigger, heavier car as it’s increase dynamic range is compensated by the effects of the cross linked suspension.

So basically our RS6’s aren’t supposed to be as stiff as S4’s! What the DRC also allows (at least from what I can gather) is for the actually geometry of the shock to change as fluid can leave the shock and thus the total height of the shock changes within some controlled range. With enough fluid loss and thus pressure loss, the thumping MAY have been the internal piston in the shocks bottoming out against the top of the shock casing! I Don’t Know for sure.

My Two Cents Worth.

Mike

[SoCal]

Paul, Ben and Steve:

You don't know how close you all were to having yet another RS6 with you that day. When were you together at Pacific Audi? By coincidence, I happened to be there last Sunday in my blue RS6, though not for a repair.

Glad to hear your problem is finally fixed, and the explanation for why it seems less stiff seems logical.

It is indeed odd that Audi has such a wide tolerance range for acceptable stock pressure in the DRC system. Higher pressure could have explained both the stiffer feel you remember and the propensity to break, I guess. I haven't noticed mine to be overly stiff, and it is unchanged since new. And no maintenance issues, either. Let me know if you'd like to compare another local car. Always happy to help a fellow driver.

:addict:

[s42ski]

Benman, how have you avoided plates for three years!!!! I got a fix it ticket at LAX (Los Angeles Airport) while the car was parked in the lot ( some airport cop with too much time on his hands)(:()
mad

Aronis, the interesting thing that Willie (Audi "fixit guru" to quote Paul) told us was that the DRC was basically "bulletproof". I dont know what type of bullets we are talking about.

Also shocks and the "feel" they give the car are highly subjective unless the car is unsafe like yours was. My car was definetly stiffer when I first got it, but it is still quite stiff compared to most other cars.

[Benman]

Hmm.. how do I avoid tickets? Easy, don't pull over! Kidding, kidding... Don't know, just have. And even if I get one, I think it's like $40 bucks or something... How much was yours? The Wife has actually been asking me when I'm finally going to put the plates on. Maybe this year... we'll see...

SoCal, was that your Mugello car there with the aftermarket rims around 11:00am Wednesday? That car had a little less bounce than the rest of the RS 6s there...

Ben:addict:

[Hy Octane]

Yes, its a bit frustrating that I have to now settle for a car that has completely different driving characteristics than it did before.. Not sure why AoA dosent know about this, but what can you do? Actually, to be honest, with the horrid road conditions we now enjoy here in SoCal (we used to have beautiful roads, but now pothole city) this softer ride actually makes life in the city easier. Its just when you want to hit some corners with an M5 or sumsuch that I notice the difference. Cant enter or exit corners as fast.. the car is more unsettled than before..

The reason I didnt get H-sport sway bars was because it didnt need them. But now it does, and so I am going to get those installed soon. ( Ben? PM box clear now.. sorry)

You just get tired of looking at blank faces while you try and explain how your car used to ride and waiting for them to explain why. They dont know, and what they dont know, you cant get..
I do know that they make 2 different shock choices for this car. The black ones (stock) and the yellow ones (sport).. maybe a set of yellow sport shocks would do the trick.. we'll see..

Thanks SoCal.. When we do meet up we'll have a push on your fender and see..Thanks for the offer tho!

Ok ..Thats all for now..

[Benman]

Originally posted by Hy Octane


The reason I didnt get H-sport sway bars was because it didnt need them. But now it does, and so I am going to get those installed soon. ( Ben? PM box clear now.. sorry)



You can contact anyone over there, they can help. Mark Hotchkiss (and his brother) is the man, but usually, he is out of the office, so just go with any one the operator patches you through to. Good folk.

Ben:addict:

[Hy Octane]

OK H-sports ordered.. will be here when I return from Hawaii..

Also, going to go to LaBree to have a new exhaust system (cat-back only) designed for the RS6..

More power and a higher race tone as compared to the stock tugboat..

More in 2 weeks..

[s42ski]

Ben, it was like $40 - it was actually worse than no plates, I had just the rear plate on since I did not like the look of the US plates on the front. He gave me a ticket for no front plate. I think the cop was checking out my car since for him to see no front plate required getting out of his car to see the front ( I was pulled in against a wall of the parking garage!)

LAX has been unlucky for me - I also got stopped (no ticket) for illegal window tint.

[SoCal]

s42ski: LAX police are notorious for giving out fix-it tickets for no plates, brake lights, you name it. I've been fortunate there over the years, but that's mainly because I hardly ever go to the airport in my own car. We have no front plates on any of our cars (they look horrible). Got a $40 ticket while parked legally at a parking meter in Santa Monica for no front plate on my RX-7, but that was about 5 years ago. Otherwise lucky, I guess.

Paul, we can meet whenever you want for a comparo. I hope the mods work out. They sound good.

Ben: Nope, blue RS6 on Wednesday wasn't me. My rims - and everything else on the Beast - are stock and I was at Pacific only on Sunday for an hour or so. Wonder whose it was. Did you say they had another one for sale? Not in their on-line inventory. Just curious.

Cheers all.

[s42ski]

SoCal, I thought the one in the lot might be for sale since it did not have plates and had a dealer registration holder on the front windshield.

Of course it might be someone who just does not mount the plates':D' ...Ben ????

I also checked the online inventory and did not see it.

[Benman]

Originally posted by s42ski
Ben, it was like $40 - it was actually worse than no plates, I had just the rear plate on since I did not like the look of the US plates on the front.

I hate the way front plates look as well. $40 bucks is money well spent IMHO. :thumb:

Ben:addict:

[Aronis]

Yellow? SPort Shocks? What? Any more info on that?

Mike

[Hy Octane]

Mike. Quisha mentioned that they made two kinds of shocks. Black=standard and yellow was sport.. I believe the yellow ones are for the RS6+.. stiffer and lower.. maybe he'll chime in here..

[Qisha]

two kinds of shocks. Black=standard and yellow was sport..

Correct. The standard sport suspension comes with black Shocks, the sport suspension plus (as available for the RS6 plus) uses yellow Shocks. These as well as the springs are noticeable stiffer from stock. The springs will also lower the body by 10mm. Some customers complain about this set up as it is too stiff for daily driving. I can 2nd that, for high speed Autobahn driving you might get tired by the rebound. If you are interested i can provide you with further details, like part numbers.

You are using:

http://www.rs6.com/gallery/data/503/1460drc_set.jpg

[Hy Octane]

Interesting because what you describe as the yellow sport ride quality is exactly how my car rode before the replacements were done.. It was about that much lower too. Incredibly stiff over the slightest bumps.. bone jarring.. But it handled great!

Thats why I was so upset that the ride now is softer .. Could it be that somehow some of us got these stiffer ones from the factory? Would sure explain alot..

Quisha, can the standard RS6 use the yellow shocks without changing the springs as well?

[gregoryindiana]

Much as I would like the stiffer ride of the Plus Yellows, I certainly won't be messing with my current suspension internals with all the troubles that others have had.

The H sport bars are an exception, I have those in the box and am waiting for the chance to get to someone with the smarts to install them for me; probably Chicago in October.

[jimmy94507]

Doesn't take an expert to install the bars. The instructions that came with the bars are pretty clear. A good tire or alignment shop should be able to change them in short order. Have them look at the instructions and give you an estimate. Our local offroad shop did the job for $120 (about 2 hours, including reading the instructions several times)

Regards, Jim