DRC Recall in US/Canada

[ArthurPE]

the system volume must change, if it were constant when one shock went into bump it's opposite corner would raise by the same amount.

the fluid makes the diaphram 'gives' or absorbs by compressing the gas, from what I understand...the shocks are isolated by the accumulator
and the fluid is non-compressible

also some of the state change (pressure delta) is made by forcing fluid thru the orifice making a pressure drop/loss

although the 'fluid' doesn't go from side to side (since the volume is constant and filled with a noncompressible fluid) the hydraulic force is transferred, which is the principle behind its operation...

see if I can find a pic

[Steve_C]

I think Audi say 14 bar ideally with 12 as a minimum

[lengster1]

Ok so looking at the diagram the accumulator acts as a damper between the two dampers if you like? It will transfer some of the fluid from the compressed shock absorber to its opposite one in the system? Correct yes/no?

[Mike_Bike]

There is an extra port in the centre valve by the looks of things, when both shocks are compressed (so a bump in a straight line) the valve is open and the fluid in the dampers can pass through both the normal ports in the shocks and the one in the centre valve.

Then under roll when one shock is in droop and the other in bump the valve shuts isolating the two shocks and removing the third port which makes the dampers stiffer in roll (two passages instead of three = more resistance)

that is my guess from looking at the diagram

[lengster1]

That was my thinking also,if you went into a big dip in the car and compressed all struts it has to go somewere ie the accumulator

[ArthurPE]

if you compress both: they both pressurize (compress) the accumulator and the forces cancel, resulting in little movement...

if only one compresses: fluid (actually pressure) is forced to the accum and fluid thru the shocks piston orifice
this is balanced by the other shock which is expanding so it will take pressure from the accum that the compressed one supplied conteracting the internal forces, ie, counteracting the opposite damper...

the net system volume stays the same
for a given shock you have 2 chambers, say upper/lower, and when neutral the V for each is 50/50, piston in the middle, when compressed the piston moves altering eaches volume, say 40/60, but the total remains the same...fluid doesn't really 'flow' to the accumulator per se, a force is hydraulically transmitted...

it's a clever system, and I really like the way it drives/rides/feels
very soft and smooth over small disturbances, and firms up when the impulse or movement gets bigger

[ArthurPE]

Ok so looking at the diagram the accumulator acts as a damper between the two dampers if you like? It will transfer some of the fluid from the compressed shock absorber to its opposite one in the system? Correct yes/no?

that's a good way of looking at it, but not really fluid movement, but pressure or force, transmitted by the incompressible fluid...

so hydraulic force is moved back and forth, not so much fluid...

[ArthurPE]

That was my thinking also,if you went into a big dip in the car and compressed all struts it has to go somewere ie the accumulator

the fluid actually goes thru the shocks orifices on the piston...the 'force' is absorbed by the accumulator...and the counteracted by the force from the other shock...

think of 2 garden hoses of the same ID, length, etc., each fed from a spicket with 50 psi...
if you connect them together no water will flow...and the pressure in the middle will be 50, not 100...

now put a sealed isolation diaphram between them...

[P_G]

I wonder if I have a problem with my accumulator. Some days the DRC is fantastic and works as it should, but on some occasions the rear feels as jittery as if the shocks had broken (you know when you go past a car with a broken shock and it is bouncing up and down like mad) and the front occasionally vibrates and then stops as if the front nearside wheel is not balanced correctly but I have had them all done.

Like I say some days its great, some days its not. No clunking, all shocks are dry. Wierd.

[philipwalker]

Reminds me of the setup on old Leyland Metros Hydro-gas progress eh?

[ArthurPE]

imo Audi could have saved themselves a lot of grief...
just put in a system like the tire pressure monitoring
even if it is only interally accessed via vagcom...

log pressure over time...say ever 500 miles or something...
if it's a nice gradual decrease, normal leakage (anybody ever see a tire that didn't need air once in a while?)
just charge it back up...
if there is a disjoint step, then rapid decrease, something 'broke'
or if it leaks in 5k miles, vs 35k miles, the seals/bushings are shot

[rs4v8]

first, you need to simmer down, you're froathing at the mouth

Am I? Mmm, nope......

it's closer to 0% than 100%

On this we do agree

I'm basing it on what Audi says... <1%, considerably
why don't you ask them the failure rate?

NO Arthur. At best you are basing it on what Audi US are saying (if they are giving you the truth - and for the final time - why would they?

you amuse me, as in funny, 'ha ha'

That wasn't my intention you pompous ass!!!!

I'll take Audis numbers over an internet poll

Audi US FFS!! 135 instances are now begging you to reconsider your stance but you just can't and won't see it!

stop being cynical/mean, or YOUR hydraulics are going to blow

I am perfectly calm my friend. as far cynicism and being mean goes, you have just won the world championship in audacity for coming out with that one! and I mean the proper world championship not some mickey mouse baseball-type "world" series!!

[rs4v8]

Im not for one minute calling you a liar,im just saying stand back and look at the bigger picture,for me there is already enough proof on this forum alone that in the UK we have a significant failure rate,audi i feel accept this and have put a measure in place which i believe to be reasonable but perhaps not ideal

lengster, 100% correct my man.

(and I include the first bit ArthurPE)

[scaghead]

i think we have sussed after twelve pages rs4v8, you are not agreeing the 1 percent view..but you are acting like a child with your sarcastic posts aimed at arthur and p-g, give it a rest fella. and stop showing off your big sweaty jacks

[rs4v8]

i think we have sussed after twelve pages rs4v8, you are not agreeing the 1 percent view..but you are acting like a child with your sarcastic posts aimed at arthur and p-g, give it a rest fella. and stop showing off your big sweaty jacks

ok