Front License Plate Mount - Mercedes Benz SLK Forum

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#1 Old 02-27-2018
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Front License Plate Mount

Apologies to all those who have chosen this route, but I HATE the non-centered license plate look. I also recognize that if you drill into the visible bumper, you're limiting your resale options later on down the line. Probably like most of you, I've looked at whatever mounts available commercially, and I've come up short. The generic ones don't seem like they have a place to mount on our cars, and the only custom one attaches to the tow hook, meaning it's off-center.

So I've decided to create one specifically for the R172. This thread will chronicle that effort.

Step 1 is the cardboard prototype. It is a two piece unit, the car mount and the plate mount.

Underneath the front, there are two bolts that are 8 inches to the right and left of center that connect the bumper to whatever is up there to connect to. These are going to be anchor points, and they will attach to the points on the car mount, highlighted in red in my first photo. The tabs shown in blue are there for alignment and stability, and fit above the bottom bumper wall. The two black diamonds mark the initial locations of the mounting holes, and this section goes below the bottom bumper wall.

The plate mount will mount onto the car mount by way of some kind of fastener. It would be really nice if the car mount is strong enough not to need to be fastened to the bumper, but I don't know yet. If so, then bolts will protrude down from the car mount, and the plate mount will attach to those. If the car mount needs to be attached to the bumper, then I guess there will be screws that point in the other direction. Or maybe a couple of big nylon fasteners will do the trick. I'm flexible on this point.

Everything fits pretty nicely, so next step is to measure and put it into CAD. My first print will be the car mount, made of plastic. Wish me luck!

Here are the parts of Prototype 1:



Here is the assembled contraption, from the rear:



And this is what it will look like from the front:

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#2 Old 02-28-2018
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I suggested something similar in another thread on the same subject. If you were to cut the same shape from a sheet of 3mm aluminium and either bend it yourself, or have a metal shop do it, there would be no need to have any attachment to the bumper.
Maybe add a couple of foam or rubber pads between the back of the bracket and the bumper to prevent any potential marking of the bumper.
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#3 Old 02-28-2018
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Wow... the first idea was EXPENSIVE. I know that's usually a given for Mercedes stuff, but c'mon!
I might be able to go with a structurally strong plastic. We'll see.

I started looking around, and got inspired by this. It's secure, lightweight, and removable.
The two forks secure the plate mount to the bumper mount.



Drawing from this, the new and improved crossbar, first, the way it would appear under the car, then looking at it from the road up.
The little holes are for screws to secure the bars in the barrels.





In the next installment, the plate mount.
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#4 Old 02-28-2018
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Quote:
Originally Posted by Windinmyhair View Post
I suggested something similar in another thread on the same subject. If you were to cut the same shape from a sheet of 3mm aluminium and either bend it yourself, or have a metal shop do it, there would be no need to have any attachment to the bumper.
Maybe add a couple of foam or rubber pads between the back of the bracket and the bumper to prevent any potential marking of the bumper.
I like that... a couple of rubber grommets could protect the bumper in the case of my latest idea.
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#5 Old 02-28-2018
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Originally Posted by mightycpa View Post
I like that... a couple of rubber grommets could protect the bumper in the case of my latest idea.
Have you seen the ones that mount through the grill such as this:

https://www.youtube.com/watch?time_c...&v=Q2xuJQWv-28

or this


I used a modified version of this to mount my licence plate/license plate frame to the grill of my SLK350. It's very solid and it looks OK I think.
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File Type: jpg Front License Plate.jpg (45.4 KB, 32 views)
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#6 Old 03-01-2018
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Wow! I think yours looks the best of all of them. (Maybe it's just the car.) I have to hand it to you, that is one clean bend on that front plate, you are a master craftsman! I'm afraid I would fold and crease my Virginia plate if I did that! I don't feel a need to reinvent the wheel, I just want it to look the way I want it to look, and yours seems to fit the bill. I like the look of the first video ok, I'm not crazy about how the 2nd one turns out, especially after seeing yours hide the hardware completely. Maybe it is the addition of that black plate frame too. Not sure, probably a combination of all three things. I could live without the bend in the plate, but . Great job!

Mind sharing your secret sauce? Which one did you copy and where did you make the improvements?
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#7 Old 03-01-2018
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Originally Posted by mightycpa View Post
Wow! I think yours looks the best of all of them. (Maybe it's just the car.) I have to hand it to you, that is one clean bend on that front plate, you are a master craftsman! I'm afraid I would fold and crease my Virginia plate if I did that! I don't feel a need to reinvent the wheel, I just want it to look the way I want it to look, and yours seems to fit the bill. I like the look of the first video ok, I'm not crazy about how the 2nd one turns out, especially after seeing yours hide the hardware completely. Maybe it is the addition of that black plate frame too. Not sure, probably a combination of all three things. I could live without the bend in the plate, but . Great job!

Mind sharing your secret sauce? Which one did you copy and where did you make the improvements?
Thanks. Glad you like it.

Here is what I did. I'm an ex-Mechanical Engineer (retired now) so I went a bit overboard on this

I started with the a BOZZMOUNT MG bracket from Slybrackets (the first link), specifying the smaller 1/4" x 1/2" grill opening version https://www.slybrackets.com/store/#!...617/category=0 , and the Mercedes curved license plate frame Black curved slimline license plate frame

I really like this bracket. It's very well thought out from an Engineering perspective. The bracket mounts the license plate/license plate frame further from the grill than I ended up with, and it's designed for a flat plate so the attaching screws end up at a bit of an angle on the curved license plate holder, but screw caps can cover this. It would probably work, as is, for most people. However I wanted it tucked in closer to be as unobtrusive as possible. So I did the following mods.

1. Bent all the bracket parts to approximately match the curve of the Mercedes curved license plate frame. The secret to bending the parts, including the license plate, is to find something with a suitable curve to bend them around (it doesn't have to be exact). I used the wide curved arms of an armchair we have to help bend the parts around. The only hard one was the 1/4" square tube bracket cross member which required leaning on it pretty hard to get it to bend. That one I used the edge of a garden hose reel, as the armchair arm wasn't sturdy enough for the extra force needed. The end result was slightly more a vee than a curve, but it's hidden from view in the final assembly.

2. Instead of the 1" long spacer/screws that screw through the grill openings, I used the two extra 1/2" un-threaded spacers that come with the bracket and two purchased 5/16-18 screws to secure the bracket through the grill openings.

3. This got the bracket to where I wanted it but the legs of the L-brackets that hook through the grill stuck out to far, preventing the license plate reaching the bracket. Cutting the L-brackets would have meant I couldn't use the 1/4" cross member, which provides useful extra stiffness, so I made some spacers to go between the L-brackets and the back of the grill and screwed them onto the L-brackets. I'd have liked to use aluminum, but only have some rudimentary tools, so I used wood, sprayed with multiple coats of outdoor paint. Hopefully these will hold up. Making these as thick as possible, while still allowing the L-bracket/spacer to pass through the grill openings, moved the legs of the L-bracket back just far enough to be behind the bracket.

4. The 1/4" cross member normally sits behind the bracket frame but with my modifications now had to fit inside the bracket frame, and it was about a 1/4" too long. So I cut a little off either end.

5. Cutting the ends of the 1/4" cross member reduced the depth of the threaded holes on either end, so now the screws that go in those holes were too long. So I cut these down in length a bit. I could have purchased shorter screws.

6. Here's where I really went crazy . Everything now fitted and the bracket was pretty firmly secured. However I'm a bit of a perfectionist and felt the bracket could be just a bit more rigid. So I got some Neodymium magnets https://www.apexmagnets.com/3-4-x-1-8-countersunk-ring . Be careful with these. They're very strong and can pinch skin as they snap together or to other metal. Keep away from children. definitely not playthings. I attached two of these, with screws, to the slot in the wide bracket cross member just inside the mounting screws, using small nylon spacers that I cut to size, to center the screws in the slot. I then glued two more magnets to matching positions on the back of the license plate, so the back of the license plate is held firmly against the bracket by the magnets. To get the correct position for gluing the magnets, I let the license plate magnets attach to the bracket magnets then assembled everything, then used two more magnets on the outside of the license plate to locate where the other magnets were. Then I stuck tape around those magnets to mark their location, disassembled everything, put magnets where the tape indicated on the outside of the license plate, then located the position of those magnets using more magnets on the inside of the license plate, and marked those magnets position with more tape. I'd left the license plate magnets attached to the bracket magnets so now I just put a thin layer of glue on the faces of those magnets, and glue on the inside of the license plate frame where indicated by the tape, removed the tape and assembled everything. I then replaced the two magnets on the outside of the license plate to hold the license plate frame firmly against the magnets behind it, while the glue set. I let the glue set for 24 hours then removed the magnets on the outside of the licence plate. I used Loctite Marine Epoxy just because I happened to already have some. Oh and I used Loctite 242 (available at Home Depot) thread locking compound on all threads to prevent anything shaking loose (already had that too). So now the bottom of the license plate/license plate frame is attached to the bracket, the top of the license plate and the top of the license plate frame are screwed together, and the license plate is held firmly to the bracket with the magnets. If i'm ever in a wreck the only thing guaranteed not to be torn apart is my license plate mounting

7. Not a mod exactly, but I went with a specialty license plate that has white lettering on a black background, instead of the standard black lettering on a white background, as I think this blends in better.

8. The Mercedes curved license plate frame came with screw caps but they were a bit thick so i went with these instead 12/12 Snap-Caps - for #10, #12 & 1/4" screws | Pro-Dec

9. Almost forgot. The license plate frame doesn't touch the car but, just in case, I edged it with a soft rubber edging strip https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

That's it I think. If I was doing it again I might try and do it from scratch rather than use the slybrackets bracket, although I do like how it works.

if you have any questions, just let me know.
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#8 Old 03-02-2018
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I guess my first reaction was to laugh... only an engineer would remember that he reacted to developments on the ground by using 5/16-18 screws on a project done some time ago! I knew then I was in good hands.

Thanks, I'm going to ruminate on this a little bit... it took me a couple of reads and comparing to the video to get a sense of where and how you made your mods. I especially appreciate the tips on bending. Long story short, it seems like you succeeded in moving the spacers from in front of the grill to behind the grill, thus bringing the plate mount closer to the grill.

I'll admit that step 4 puzzled me a little bit at first. It took me a while to understand that when you cut the spacer screws and added the wood spacers, Spatial reasoning is not my best talent. I've got to actually work with something to "see" it, but the video helped.

I may be back with some questions, but at a minimum, I'll be back with a picture.

Thanks for your help.
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#9 Old 03-03-2018
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Originally Posted by mightycpa View Post
I guess my first reaction was to laugh... only an engineer would remember that he reacted to developments on the ground by using 5/16-18 screws on a project done some time ago! I knew then I was in good hands.

Thanks, I'm going to ruminate on this a little bit... it took me a couple of reads and comparing to the video to get a sense of where and how you made your mods. I especially appreciate the tips on bending. Long story short, it seems like you succeeded in moving the spacers from in front of the grill to behind the grill, thus bringing the plate mount closer to the grill.

I'll admit that step 4 puzzled me a little bit at first. It took me a while to understand that when you cut the spacer screws and added the wood spacers, Spatial reasoning is not my best talent. I've got to actually work with something to "see" it, but the video helped.

I may be back with some questions, but at a minimum, I'll be back with a picture.

Thanks for your help.
Made some rough sketches that might help. Not to scale or anything, but might give you some idea. The first two are front and back views of the original. The other two are front and back views of the modified version (sorry, I didn't try to sketch the curve ). I have these in 3D, so can save any view you would like to see in seconds, so if you want any other views for clarification, let me know.

There are three holes in the L-Bracket that you can screw into, and the wide cross bar with the slots can screw onto the rest of the bracket in three different positions, so there is quite a bit of flexibility in how it all mounts. The bottom of the license plate/license plate frame screw onto the bottom of the U-shaped piece in this case, but you can invert the whole thing.
Attached Images
File Type: jpg Original Bracket (Front).jpg (35.6 KB, 4 views)
File Type: jpg Original Bracket (Back).jpg (29.8 KB, 4 views)
File Type: jpg Mofified Bracke (Front).jpg (25.3 KB, 2 views)
File Type: jpg Mofified Bracke (Back).jpg (17.7 KB, 4 views)
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