There's no shortage of solutions for attaching a front license plate without drilling into the bumper, but all of the ones I've seen are still visible to some degree. A couple of years ago I came up with a solution to mount a license plate with magnets and have refined the idea since. Since I had to install them on the new ///M, I thought I'd take some pictures and write up a DIY.
Keep in mind that this solution is designed to be used
only when the car is parked. In my experience, the states that require front license plates only enforce the law on parked vehicles. Thus, I wanted to keep the clean plateless look while driving, while having an easy means to affix the front plate once parked. If you want a way to keep a front plate mounted while driving, there are a number of other more durable solutions.
What you'll need:- 4 magnets. Shape does not matter significantly as long as they roughly have the same surface area. You can use 4 identically sized magnets if they're strong enough, but if you have trouble finding strong magnets, use a set of relatively thin ones (0.25" or less) and another set that's a thicker (0.5"-1") with more pull. I bought mine from McMaster-Carr.
- 2 right angle brackets and fasteners. Make sure the fastener holes match the holes in your license plate. I bought mine from Ace Hardware.
- Some sort of adhesive. Double sided foam/cloth tape works well. You don’t want too thick of an adhesive as it increase the distance between the magnets and weakens the magnetic force. Make sure it's rated at a decent temperature range, as you don't want the adhesive to melt when it gets hot or get too brittle when it gets cold.
- Duct tape
1. Attach the angle brackets to the bottom mounting holes of your license plate.
2. Find the polarity of your magnetic pairs. The magnets will only stick together one way. Mark the faces that go together.
3. Tie the thinner magnets with the marked face up on the other end of the angle bracket with duct tape.
4. Remove one of the grilles. I do this by pulling down on the slats where the catches are (shown below) and popping the top out. It takes a little force, but be careful you don't snap anything.
5. You should now be able to reach in and feel the inside of where that lip is. It's dirty in there! Reach in with a moist rag and wipe the dust/debris off the lip so that the adhesive will stick (later).
6. Then, place one of magnets on top of that lip, marked side facing down. Here's what it looks like in that lip.
This shows an approximation of where the magnet would be from the outside, if you could see through the bumper.
7. Line up one of the magnets on your license plate assembly to that magnet.
8. Put the other magnet in. It should snap to the location of the other magnet on the license plate bracket. Adjust the position by sliding the license plate bracket left/right/forward/back.
9. Once you're happy with where it is, reach in and take out one of the magnets. (The other magnet should be strong enough to still hold the plate in place.) Affix the adhesive to the marked face of the magnet you took out.
10. Place it back into the bumper adhesive side down. It should snap to where the corresponding magnet is on the outside. Press down to secure the adhesive.
11. Repeat with the other magnet. With the bracket still on the outside, you’ll easily be able to tell where it needs to mount on the inside by following the magnetic pull. Here's what the inside looks like with both magnets installed, to give you an idea.
Bracket installed:
Detail of bracket from side:
...and below:
Bracket removed:
I keep my license plate under the passenger seat.
Do NOT put the plate, or anything else for that matter, under the driver seat. It can slide out under hard braking and get jammed up near the pedals, which can be very dangerous. This is common sense.
Don't forget to take it out when you park in a spot where you know the license plate law is enforced! For me, this is only when I head into the city or park at one of the airports. More importantly, don't forget to stow it away when you're ready to drive off. I've accidentally left it on and driven on the highway with it, but depending on the strength of the magnets you chose, the license plate may or may not stay on if you hit a bump at 90 mph…