Tech Article Title Author Date
S4/A4 Mud Guards Avram Dorfmanon 2000

There have been a number of questions about installing mud guards on the S4 forum. It's pretty easy, but it took a while to get it straight. I'm writing this FAQ in hopes of making the process easier for others.

For starters, here are the part numbers. These are Audi part numbers. I got mine from Clair Parts Express. The side skirts on the A4 are different than on the S4, so don't get the wrong ones!

  • S4 front mud guard (pair) 8d0-075-111-ba
  • A4 front mud guard (pair) 8d0-075-111-b
  • S4/A4 rear mud guard (pair) 8d0-075-101-a
Next are shots of the directions that come with the mud guards. This HOW-TO is really just an extension to the directions. But for the lack of any written instructions, they'd be perfect. As it is the drawings give you a pretty good idea. Please go over them before continuing. Don't worry about the writing - all it says is "equipment is subject to change" in seven languages.


Order the appropriate kits using the part numbers above. They should cost $35 to $40 each, not including tax or shipping, etc. It's a good idea to wash the car first so you don't trap grime, especially salt, under the flap. Also, you'll have to take the rear wheels off to install the guards, so you might want to take advantage of the chance to clean them on the inside - I did.

 You'll need a crescent wrench like the one shown in the diagram - it will need to open at least 2 inches. You'll need a hammer for the bottom clips. You'll also probably need a Torx (star) screw driver, take a look. If you're lucky, yours will be philips like the instructions suggest. The Torx I bought says "T25" on it, but the rack on the store where I bought it said "#10" (I think) - make sure you try it in one of the screws before you buy it!

Also, it's a good idea to do this in uber-freezing weather. Personally I did it in unter-freezing weather, and I cracked one of the clamp anchors - luckily not such that it was unusable.

Rear Installation

Ok, the rears are easier - all though not necessarily faster. First you have to take one of the rear wheels off. I'll let you figure this out on your own, but for the uninitiated, I'll make two comments: Audi's have lug bolts, not lug nuts, and you screw that funny looking pin from the jack kit into the top lug hole to guide the wheel when you're putting it back on.

Ignore the rumors that you need a drill for this. The screws are self tapping. You probably want to clean an inch or so back from the wheel well so you're not trapping dirt (or worse yet salt) under the flaps. The hold them in place with one hand, and align them by eye. Make sure the bottom looks parallel to the ground, and that the lip that goes around the side is actually in contact from top to bottom - if it is slid down too far, there will be a gap between the bottom end of the lip & the car.

Then push the flap in place pretty hard with one hand to make sure it's a good seal - not that it's that important... Then with the other hand, put a screw on the end of a philips screw driver (ok, you probably should have done that first). Guide it through the hole, press & start turning. It will dig it's way in, just keep turning. Go until it's reasonably tight - not metal in metal tight, more like lid on jar tight. Finish the rest of the screws, and put the wheel back on - that's it! Shouldn't take more than 20 minutes per side, not including washing the inside of the rim.

Front Installation

Turn the wheels all the way to the left. Ok, there are only two screw holes in the front guards, and they don't come with any screws. There are two screws inside the wheel well - remove these now. Incidentally, one of mine wouldn't come out, so I just did it with one screw - that and the three clamps appears to be more than enough.

The Screws

Line up the cuts in the molding with the side skirt approximately - you'll get a chance to fine tune it in a minute. Hold it in place, and take the torx screwdriver with the screw already on it ('cuz you already did that, right?) and get ready to put it in the hole that's closer to you. Now push the mud guard in and up really hard. If you have the luxury of a second pair of hands, have them do the pushing, and use the flashlight to determine if you've pushed far enough for the mud guard hole to line up w/ the hole in the car that the screw came out of. Once it is, push the screw back in & start turning. Tighten it about 1/2 way (3-4 turns), enough so it stays in place, but not so much that the guard can't move.

Now put the second screw in. You'll have to do some more pushing to get that hole lined up. You may even have to push in such a way that the molding gets misaligned. Have no fear. Once you get that screw in, tighten it also only half way.

 Now adjust the guard so the molding matches your side skirt. I had to pull up on the guard really hard to get it in the right place. Once it's there, keep holding it in place, and tighten the closer screw all the way. Then tighten the other screw.
The Clamps

Ok, these are funky little things. Take a close look at the instructions to see how they'll be aligned, The two larger clamps are for the bottom. The 6 black plastic anchors are identical. The top two rubber flaps fold behind the guard. They get pinched between the 1/2 inch of body metal that is folded into the wheel well, and the plastic wheel well lining. Do the top one first - with one hand, push the plastic lining away from the metal so there is a gap. With the other hand, fold the flap behind so it goes between the metal and the lining. Just shove it in there - there's nowhere else for it to go. You can't really tell if it's in there or not without a mirror - I just felt it and took a leap of faith.

Now put the plastic anchor in place. Then position the clamp so it's ready to go around the folded flap, and push the fork of the clamp into the anchor. You should be able to get the first "click" by hand. Then do what the directions show with the crescent wrench.

The middle clamp goes on the same as the first, but it's easier to get the flap behind the metal once the first clamp is in place

The middle clamp goes on the same as the first. It's easier to get the flap for this one behind the metal once the top clamp is in place because the top one is already creating a gap between the metal and the lining.

The bottom clamp is a little more difficult. It is the larger of the clamps because it has to go around more and thicker material. It goes around both the bottom of the fender liner, and a little lip that sticks off of the frame. There is a small gap between these to pieces (Ethernet experts might call this an "inter-frame gap" 8-). It doesn't look like the clamp is big enough, but the fender liner is flexible, and the clamp will squeeze it to the frame. Fold the bottom flap around both pieces, and start to push the clamp over them as far as you can. Hold the clamp in place, and fit the anchor over it's fork as in the diagram. Finish it with the crescent wrench. You'll probably have to tap the clamp with a hammer afterwards to get it all the way in place.

Right Side

The bottom clamp on the right side is the hardest because there is a plastic cover of some sort behind the frame lip, and it gets in the way of the clamp. Technically the right way to do this is to remove the cover first, wrap the flap around both pieces, and then put the clamp around the whole mess just like you did on the other side.

However I got lazy. You can't fit the rubber flap between the frame piece and the cover, but you can fit it between the frame piece and the liner. Then you can put the edge of the hook part of the clamp up against the gap between the cover and the frame. You won't be able to push it in there by hand, but if you hold it at the right angle, you can tap it in with the hammer. Do it just enough so it doesn't fall out. The clip will be at an angle which will still enable you to fit the anchor onto it - do so. Then finish with the crescent wrench like on the other two. I had to do it part way with the crescent wrench, then go under and hammer the clip the rest of the way on, and then finish with the crescent wrench.


Yikes! You're done! Here's a little photo gallery of how my car looks with the flaps on. Please feel free to email me questions!


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