DIY - Exhaust Downpipes - B6/7 S4

DIY/TECH/INFORMATIVE
#1

Why: 1. Once the downpipes are out it is a fantastic time to make piggy pipes that should be done on all B6/7 S4s regardless of wither or not the car is going to be further modified for reliability or performance. Since the pre-cats are a primary cause of other issues with these cars.
2. Required for other repairs
3. Very common modification/upgrade

Background information:
Justincredible posted a thread in the B6/7 S4 section here on AR to describe why piggies should be done. Here is a link: http://audirevolution.net/forum/index.php?topic=2926.0

Recommended upgrade/better parts and other modifications:
Piggie pipes or Catless downpipes

Previous steps required:

  1. Jack up the front of the car and put it on jack stands
  2. Remove the belly pan. http://audirevolution.net/forum/index.php?topic=2922.0
  3. Remove the MAF boot and top half of the engine air box. http://audirevolution.net/forum/index.php?topic=2919.0
  4. Loosen the coolant tank so that it can be moved around for clearance. http://audirevolution.net/forum/index.php?topic=2921.0
  5. Remove the front oxygen sensors and disconnect the rear oxygen sensor bodies from the exhaust downpipes. http://audirevolution.net/forum/index.php?topic=2970.0

Tools Required:

  1. 13 mm socket 3/8 inch drive
  2. large set of wobble 3/8 inch drive extensions. (preferably locking wobble extensions)
  3. 3/8 inch drive ratchet
  4. 16 mm open end wrench
  5. 17 mm socket 1/2 inch drive
  6. 1/2 inch ratchet
  7. long ball end 6 mm allen socket

If your S4 has an automatic transmission then you also need the following tools and these can be helpful if the middle/top axle heat shield bolts are still in place on a car with a manual transmission:

  1. 18 mm 1/2 inch drive socket
  2. long 1/2 inch ratchet or breaker bar
  3. floor jack
  4. piece of wood

Tools that may also be helpful to have:

  1. 3 pound hammer
  2. 17 mm impact socket and 1/2 inch impact gun
  3. Cut off wheel or sawzall
  4. large striking prybar
  5. Assortment of different metric sockets and wrenches
  6. Penetrating oil - PB blaster, WD-40, mixture of ATF and Acetone, etc

Steps:

  1. Use the 17 mm socket and 1/2 inch drive ratchet to loosen the center exhaust clamps and slide them down the catback so that the back of the downpipes are free to move. They are usually pretty rusted and are not easy to loosen and move, if you live anywhere that sees snow and road salt. That is why I recommend the other tools because I have had to spray them with penetrating oil, hammer the crap out of them, and sometimes even cut the clamps off.

http://jhmotorsports.com/products/pictures/piggies/JHM_Piggie_Pipe_Install_Help.jpg

Other times you will see clamps like this:

http://i284.photobucket.com/albums/ll37/Jimmybones777/20140902_193242_resized_zps72e2accc.jpg

This next step is required on a car with an automatic transmission. It is also helpful on a manual transmission car if the middle/top axle heat shield bolt is still in place.

2a. Lower the rear of the subframe. To do that you need to put the piece of wood on top of the floor jack and then jack up one side of the subframe by the transmission mount. You are not trying to lift the car off the ground but instead this is to support the subframe while removing the bolts. Use the 18 mm 1/2 inch drive socket and 1/2 ratchet to remove the bolts that hold the rear lower side cover off. Then lower that side of the subframe and repeat the process on the other side of the subframe. Warning these bolts are on tight and are rather long so be prepared for a few curse words to come out.

http://www.myturbodiesel.com/images/b5/bal/bal8.jpg

The green circled portion is what has to come off. Note: It has been a while since I have had to do this on an automatic car so the rear bolts maybe 13 mm instead. If anybody can confirm for me that would be great.

http://www.audiworld.com/tech/pics/wheel43_small.jpg

2b. If you have a manual transmission car then you want to put the floor jack with the block of wood under the transmission crossmember like it is pictured below. I am using a pole jack in the picture below since I have a lift but most people are going to do this on jack stands so a floor jack would go in the same place.


http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_120808_resized_zpsab02a1cb.jpg

Then take out these three bolts on each side and then lower the floor jack and transmission crossmember.


http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_120820_resized_zps365745ea.jpg


http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_120825_resized_zps23cd3f26.jpg

  1. Remove the three 6 mm allen bolts that hold the axle heat shields on and then remove the heat shields. There is a metal heat shield above the inner CV joint of the front axles on each side of the transmission. I use the long ball end 6 mm allen socket, some extensions, and a 3/8 drive ratchet to remove those bolts.

Front bolt on the driver’s side:

http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_113746_resized_zps1a00fde2.jpg

Middle/top bolt hole on the driver’s side. This bolt was already removed by the owner. Pro-tip: do not put this bolt back in on either side since it is such a pain in the ass to get in/out.

http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_113720_resized_zpse4a28afb.jpg

Rear bolt on the driver’s side:

http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_113657_resized_zps4fd8b38f.jpg

The passenger side is basically the same but the bolts are in a slightly different place.

  1. Remove the three 13 mm nuts that hold the downpipe flange to the exhaust manifold on each side. They can be rusty and stuck. I like to use a whole set of wobble extensions to get on those nuts.

Driver’s side:

http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_110711_resized_zpsa62abfec.jpg

Passenger’s side

http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_110016_resized_zps1a10ffd2.jpg


http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_110047_resized_zps318c9011.jpg

  1. Remove the 16 mm bolt that hold the downpipes to the transmission on each side.

Driver’s side:

http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_110025_resized_zps6a799c2e.jpg

Passenger’s side. You can see the head of the bolt through the opening:

http://i284.photobucket.com/albums/ll37/Jimmybones777/20140903_110037_resized_zps8600ac2d.jpg

  1. Remove the downpipes. They simply pull out at this point.

  2. Gut the pre-cats if you are reusing the stock downpipes. Also a good time to install catless downpipes too.