Goal: The goal for this installation was to reduce body roll without increasing ride harshness. Replacement of the standard springs and shocks with H&R Sport Springs and Koni Sport Shocks greatly improved the handling of the vehicle over the standard suspension. With the adjustable shocks set to soft, a comfortable ride and good road feel resulted. The lowered center of gravity provided for good cornering but excessive body roll accompanied turns even at moderate speeds.
Order and obtain the sport sway bar from your dealer. To make sure you are getting the correct bar for your model year, ask your dealer for the rear PSK anti-sway bar for your particular year and model. Note that if you took the sport package on your vehicle, you already have the PSK bar in the front and back. The rear bar retails for a little over $100, and the bushings are about $6 each. Regarding the bushings, you can re-use the original bushings depending on their age and condition. I have read some forum posts where people recommend drilling out the bushings to 19mm to accommodate the bigger bar. The part number for the bushings is the same for the standard and sport bar according to Audi. I found that by simply greasing both the side of the bushing that contacts the bar and the exterior area of the bushing that contacts the retaining bracket, one can easily use the unmodified bushing - just the way that Audi specifies it. I couldn't recommend boring out the bushings, remember that the goal of this modification is to restrict movement in the suspension, not introduce slop into it.
I decided to paint the bar before installing, for additional corrosion protection and to distinguish it from the standard bar. The bar comes finished in glossy black, better resistance to scuffing of the new painted surface is obtained if the glossy surface is sanded lightly before painting. Observe spray paint instructions and choose a good exterior enamel if you are going to repaint.
If performing this in your garage, make sure that you have enough space beyond the side of your vehicle to withdraw the entire length of the old bar out to the side. You will require two jack stands, tire blocks, a jack, a torque wrench (at least 100 pound capacity), and various sockets and open end wrenches. Start by setting the parking brake, leaving the car in park or reverse if manual transmission, and blocking the front tires. Refer to the owner's manual for the jack points, and do not use the car's own jack to hold up the car when working on it. A jack stand or blocks must be used and the standard car jack is not designed to be used for safely servicing the car from underneath. Start by loosening the wheel studs on the back tires slightly while the car is still on the ground. Jack up one side of the rear at a time, lowering the car onto the jack stands before removing the studs and tires completely.
Having removed the wheel, carefully set aside the wheel studs, you should be able to visualize the two points on each side of the car where the sway bar is tied in . One point is where the bar is held within its bushing by the retaining clamp that is bolted through a subframe member of the car, it is pictured below. The arrows point to the two 13mm nuts that are best removed with an open end wrench while stabilizing the bolt on the other side with a 13mm box wrench. You may be able to get a socket on the top bolt using an extension, but the lower bolt is definitely blocked by the metal strut visible in the picture. I would recommend removing these nuts and bolts from both sides as a first step to free up the bar from the subframe.
Next, using a combination of a 16mm open end wrench and a 16mm box wrench, remove the nuts from the bolts that secures the distal ends of the bar to the uplink arms. It is a fiber nut and should come off easily.
As is visible in the above picture, backing out the bolt is not directly possible because of its proximity to the shock absorber (yellow in the picture). Removing the bolt can be facilitated by pushing the uplink arm toward the back of the car so the bolt will clear the shock. The uplink arm is fastened to the lower control arm through a flexible bushing, so the arm will just spring back when you let go of it.
Next, using a 13mm socket and a long extension, remove the two bolts that secure the muffler strap brackets to the floor of the trunk. This is approached from under the car, loosen and remove the two bolts from the bracket on each side of the car. This will allow the exhaust system to drop down about 2 inches and is absolutely required for removal of the old bar. The mufflers will hang down as in the picture below, avoid pulling or forcing them down as this could result in damage to the exhaust system further upstream.
You are now ready to remove the old bar. Mostly trial and error will enable you to slide the old bar out around the exhaust, brake lines, shocks and frame parts. When it ultimately comes out, you will rotate the end you already have beyond the wheel well to the back of the car in a path like the below picture.
Next you will be installing the new bar. Reverse the path of removal on the old bar for the path of insertion on the new one. Once in place, I would recommend connecting the distal ends of the new bar to the uplink arms using the 15mm bolt and nut removed earlier. Technically, the fiber nut is best replaced with a new one once it has been removed if the retentive effect of the fiber material is to be optimized. I used the old nuts as they still presented significant resistance to unthreading. You will hit a definite stopping point when tightening these nuts as a sleeve through the uplink bushing limits the advance of the nut.
Now tied in place at its ends, the next step is to secure the bar through the bushing and retaining bracket to the subframe of the car. As mentioned earlier, some people have complained that they cannot use the Audi specified bushing because it is too small and have either drilled it out to the size of the bar or used a dremel to grind it out. This is neither recommended by me nor was found to be necessary. In the picture below, the bushing has been well lubricated with silicone grease on both the surface that faces the bar and the exterior surface that faces the bracket., as below. The top bolt has been positioned and its nut is capturing 3-4 turns of its thread.
Note that the pliers that is almost positioned ( I couldn't hold the pliers and the camera at the same time) to cinch the retaining bracket down over the bushing and flush with the subframe so that the 13mm nut can be threaded on. Here it is after tightening everything down and it does fit !
Next, replace the 13mm cap screws that secure the muffler strap brackets to the bottom of the car. Check that none of the heat shielding has been bent when removing or replacing the bars. If it has been deflected, you will get a not so nice vibrating noise as the muffler bumps up against it. A little ahead of schedule, I had a few minutes to detail H&R's and the Koni shocks!
Lastly, apply anti-seize compound to all the wheel studs as well as to the wheel surface that contacts the hub. Using this compound on the threads prevents them from locking up and is the only way you can get an accurate measure of torque on your torque wrench. Check with your wheel manufacturer for the optimum tightening, typically 90 foot pounds is acceptable for most alloys. Here is the bar in place from underneath.
Remove stands or blocks and lower your vehicle checking first to make sure nothing remains under the car. It is always recommended that you check back over the installation after a few days of driving, it just takes a minute to ensure that all the bolts are tight and nothing is rubbing or out of order.
Mission accomplished, one can definitely feel the rear tires sticking. Body roll is all but gone at most speeds. Ride comfort is not compromised.
Before installing the PSK bar on cars with the standard springs and shocks, you should check with your service department as this may alter the suspension dynamics and put greater stresses on the tie in points between the bar and the lower control arm and subframe. This FAQ was written as a guide to those persons wishing to install the PSK (Audi Sport) rear sway bar themselves on their A6 cars. It is just a guide written by a person with the experience of performing the upgrade on their own car. I am not a professional mechanic so please consider that when following this guide. The author of this FAQ and the website owner assume no responsibility for any damage to you or your A6 if you choose to follow these instructions. Use of these instructions is at your own risk. Good luck.