Audi A4 B7 – S6 LED Retrofit Part 2
As a follow-up to one of my more popular posts, how to fit S6 LEDs onto a B7 S-Line or S4 bumper, I often get asked how I made the grilles. I’ve even offered to make them for a few people.
The truth is, they’re not that hard to make – they just take a lot of time, or more specifically, a lot of sanding.
To make grilles like I have that will fit the B7 S-line or S4 bumper and accommodate your shiny new S6 LEDs, you do have a few options as I discuss here. I think buying the S6 lower grilles and shortening them yourself is the easiest, whereas the other options require you to know how to lay fiberglass well, or they require you to go completely custom with mesh which is hard to make look OEM.
To make shortened S6 LEDs like I did, you’ll need the following equipment:
- S6 Lower grilles. Part number 4F0-807-681-F-01C & 4F0-807-682-F-01C (left & right). They cost about $60/each from the dealership.
- Bondo – you can get a 12oz can for about $6 on Amazon
- An assortment of sandpaper – from medium to very fine. A kit like this (Amazon link) will have everything you need.
- Exterior Mounting Tape (heavy duty) to mount the grilles. It is about $5 on Amazon.
- Super Glue – I recommended Loctite Super Glue Professional Control as its easiest to use and has a good drying time (not too quick, not too slow). Available on Amazon for about $5.
- Plasti-Dip or Paint – I recommend Plasti-Dip, as I’ll explain later. About $6/can on Amazon.
- A dremel (optional, but highly recommended) – this will speed up the process drastically, saving you a ton of hours. The Dremel 200 is fairly affordable at $55 (again, on Amazon) and is supringsly handy around the house. You’ll need it to modify your bumper to fit the S6 LEDs as well, so you might as well pick one up. Avoid the cordless one, it runs out of battery way too quickly.
Total cost is about $140 for all of the supplies (without the Dremel) or $195 with the cost of the Dremel factored in.
Once you have everything you need, it’s pretty simple from here:
1) Chop off the rear mounting points
You won’t need these, and they’ll get in the way and prevent the grilles from mounting correctly against your bumper. You will see them protruding out of the back of the grille, and they’ll come off easy with either a dremel or a hand saw.
2) Cut out about an inch in length
Cut out the extra length from the end nearest the middle of the bumper – it is the flatest section and will be the easiest to mold back together. Start from the top and go through all three horizontal bars, making sure you have very straight cuts.
Then, make the same cut about 3/4″ down, so that you take out a 3/4″ section in total from the overall length in between the two cuts.
After you finish cutting through, your grille will look like this:
You’ll probably end up needing to shorten it even more, but start conservatively. By only taking 3/4″ out at first, you leave room to take out more later, but if your first cut is too big, there is no going back really. After taking out a smaller section, go test fit it to your bumper and see how it looks by holding the two pieces together. Depending on how you mounted your S6 LEDs, you may only need to take a little more out, or you may need to take a lot more out.
2. Test fit, sand, test fit, and sand until the length is where you want it
As mentioned in step 1 above, keep sanding a little off the length (or make a new cut through it) until the length is exactly where you want it. Try to sand or cut in straight lines so the two pieces mate up to each other smoothly.
Once you have the length you want, press the two pieces together and make sure they mate up flush. You might need to send the ends so that they are flat and even to ensure that they’ll mate up to each other completely and there will be minimal bondo needed.
3. Super glue the pieces back together
Once you have the desired length, use the super glue to hold the two pieces back together. Let the super glue fully dry before proceeding to the next part.
Now that the super glue has been applied, fill in the cracks where you made the cuts and reattached the pieces back together with bondo. Follow the instructions on the can of bondo exactly and don’t try to do too much at once – it dries very quickly, so it’s best to work in small batches. Let it dry a full 24 hours before you start sanding. I probably used too much, but its best to have too much and sand down to a completely smooth finish then to not have enough.
Step 5 – Sand the bondo’d area until smooth
You can start with your dremel tool using the cone shaped sanding extension, then switch to sand paper once you’ve got the majority of the excess bondo off. Keep sanding and sanding until there is barely any bondo left, just enough to fill the crack and that’s it. Then switch to the very fine sandpaper until it’s completely smooth to the touch. You can leave a little extra bondo on the underside of the grille as it won’t be visible and will add a little strength.
Test fit it one more time to make sure there are no areas on the backside of the grille or mounting points you forgot to take off, and that it will fit totally flush. Next step is paint!
Step 6 – Paint or Plasti-Dip
I prefer Plasti-Dip to finish these off, as it has a nice textured finish that will both hide any flaws as well as protect the grille a little better since its a rubberized coating. Read my tips on using plasti-dip on cars here. If you want to use paint, that’s fine too, but make extra sure you did an excellent job at sanding the area where the two pieces were joined together as the paint will amplify any flaws you might have missed. For Plasti-Dip, you do not need to primer the pieces, just go ahead and paint them directly.
Allow to dry 4 hours for every coat you put on. I put on 5 coats so I let them dry a full 24 hours just to be safe.
Step 7 – Install Mounting Tape
Install the mounting tape along the outer edges and bottom edge as shown above.
Some of you may be nervous if the tape is strong enough to hold the grilles on, and I can tell you it definitely is. I have had my grilles installed like this for well over a year. They’ve gone through track days, high speed runs, and 20,000 miles of daily driving installed like this. The only time I had an issue was when a blown out tire was left in the middle of the road, and it took out both the LED and the grille it hit so hard (I only saw it last minute and it was too late to swerve to avoid).
You could explore a more permanent mounting solution such as using a small black screw, but keep in mind that the bondo will crack if you apply too much pressure to it when drilling a hole, so be careful if you choose to do this.
Step 8 – Install on the car
The last step is as easy as applying a sticker. First clean the bumper surface thoroughly to remove any dust, grease, or anything else that would prevent the mounting tape from sticking. Then, remove the backing to the double sided mounting tape and gently install them onto the car. Hold them into place for a few minutes using firm pressure, then allow them to sit for a while before driving, preferably in the sun light so the mounting tape really has a chance to bond.
And there you have it – your custom S6 lower grilles are now installed.