- 3 Min Read
- By: David Fresne
How to Install a Metal Skid Plate (Audi B6)
I recently picked up a used Thor Skid Plate. A skid plate is nice to have if your car is lowered to protect the oil pan as well as other components and is a lot more durable than the plastic belly pan. This installation took place on my B6 Audi A4.
The install is pretty straightforward. All you need is a ratchet, a few sockets, and a way to get the front of the car in the air. The first thing to do is to install the rivet nuts. The bracket that holds the plastic belly pan is nowhere near strong enough to support the weight of the aluminum skid plate. The rivet nuts are installed into the two holes in the subframe. I bought a pack of the rivet nuts separately since I bought the skid plate used and it didn't come with them. Rivet nuts allow you to insert a threaded hole into any circular opening, creating a strong mounting point for the skid plate. Take a bolt and apply some grease or anti seize to it.
I used an piece of angle iron I had laying around, but you can use pretty much any piece of sturdy metal with a hole drilled into it. Assemble the bolt, rivet nut and lock washer.
The lock washer stops the rivet nut from turning. When you start to tighten the bolt, it will put the threaded part against the subframe so that it's permanently attached. The ribbed part of the rivet nut is not threaded and that is the section that is pulled up against the subframe.
The rivet nut is placed into the driver side hole under the subframe. I used a small dab of J-B Weld on the outside. This is probably overkill.
Now, start to thread the bolt into the rivet nut. Make sure you keep the piece of angle iron pushed up so that the rivet nut does not fall out. Once it is finger tight, begin tightening the bolt. You will feel a slight of amount of resistance as the rivet nut is pulled together. You should start to feel that the bolt begins to become harder to turn, then stop. You do not want to pull out the threads by tightening too much!
In this picture you can see the indents that the lock washer put in the rivet nut. Notice the threaded section that is now pulled closer. Repeat this process for the other side!
Next, remove the speed clips that are used for the 1/4 turn fasteners.
Depending your what car you have (B5, B5.5, B6, etc) you may use all three mounting points or just two of them. In my case, I have a 1.8T B6 Audi A4 and only used the center and passenger side mounting tab. The important thing is that you use the center one since it is metal and attached to the crossover pipe for the intercooler. Install the new speed clips which use a threaded bolt.
I found it easier to install the center section of the skid plate first and then install the side "wings". These white plastic spacers are optional, they are supposed to help direct airflow to your transmission when installed on the two subframe bolts. Depending on your engine, you may also need to use them on the front bolts. I have a 1.8T and I chose to use the spacers on the front as well since part of the plate was close the intercooler piping and I didn't want any potential rubbing problems.
Slip the front edge of the skid plate in between the bumper lip and core support and then thread one of the subframe bolts in loosely by hand. You should be able to let go while you start the other bolts.
Don't tighten them until you get all the bolts started. Now you can attach the two "wing pieces." Since I live in the Northeast part of the US, I am a firm believer in a magical elixir known as "Anti Seize" on bolts. You go through the hassle of removing a rusted, broken bolt just once and you will understand. For those of you that know what this 'Anti Seize" you most likely know how hard it is not to get it everywhere when you're using it. This is demonstrated by the picture below.
Make sure that you use lock washer on the bolts for the wings, you wouldn't want those bolts vibrating out. Once the wings are attached, snug up all the bolts, and you are done! The skid plate can be removed for oil changes and other maintenance by removing the four bolts, which is a lot easier than the billion zip ties I had holding on the remnants of my shredded plastic belly pan.
David Fresne is a Mechanical Engineering Student at SUNY Polytechnic. He likes to work on his B6 Audi A4 and motorcycle in his free time.