Some tips on A4 / S4 in-dash cup holder replacement
I found this great link here with pictures:
AudiWorld Tech Articles
Removing the long thin piece of center dashboard console trim above the cup-holder gives better access (and helps prevent damaging it) -- but it's a tricky process. Opening the glove compartment allows you to slide a screwdriver or something in behind one side to pry a bit if you don't have the special Audi tool or similar curved-tip paint can opener. Ironically, I *did* have a paint can opener, but it had a simple flat bladed tip like a screw-driver and was missing the lip.
Now, as for replacing the cup holder itself, you actually have two options, one of which I have not seen mentioned elsewhere on the web. The cup holder is sold as a single replaceable module. The module really has two sub-assemblies: the case which fits into the center dashboard console, and the slide-out tray. Most all instructions talk about replacing the entire module, which theoretically is the simple way to go. Except it's surprisingly hard in some cases to get the module out (and other people find it quite easy; not sure if this varies from one car model to another or not).
In my case, I found it easier -- and better -- to just replace the slide-out tray without even removing the module from the dash. (The reason it was better for me is that the replacement module arrived with a damaged outer case, and prevented the drawer from sliding nicely. Didn't feel like mailing it back if I could just use the piece I needed; the tray.)
So, let's back up.
Usually, what is broken, is the delicate little dual-flapper hinged spring-loaded piece that attempts to adjust to different diameter cup bases. There are very delicate little posts that hold that into the slide-out frame. They can break from abuse, or more likely from plastic fatigue over the years. Or, in my case, probably a combination of plastic fatigue combined with very, very hot weather that had most likely caused the plastic to warp and not open / close properly, which put more stress on the little posts.
So replacing the slide-out tray which contains the broken flapper piece is a viable alternative.
Removing the entire module, as is documented elsewhere, requires you to get a very thin tool in above the two sides of the module and depress the little flanges that hold it in place (see picture). Then the module should slide out.
Alternately, to replace
just the slide-out module, you need to slide it out as far as it will go and then on the
bottom of the tray, on the right-hand side (looking from the top) there is a little nub (see picture) which stops the tray from popping all the way out of the case. You can push
up on the bottom of the tray, or insert a thin metal tool (like a butterknife or thin screwdriver) in and push up with that. At the same time, gently but strongly keep trying to pull the tray out.
Now, when you do manage to pull it out, several things will happen. There is a flat rolled constant velocity spring that may pop out (or may remain attached to the module case). There is a little gear that sits on the top of the slide-out tray -- it may pop out two. So advance preparation with lots of white or butcher paper to help you find them against the dark interior (if you have that) may be in order.
Now you can just slide in a replacement tray that you've purchased. You may need to use a screwdriver to push a little to let the gear get through the opening of the module case. The gear is meant to protrude up into a gear track in the case, so by design it is taller than the opening of the case and tricky to get in. For good pictures of the gear and spring, see here:
In-dash Cupholder Repair - AudiWorld Forums