Fender side grills- posts break.

m5bb

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Here's a problem I encountered that some others may find as well.
The crappy plastic fender grills.
When removed 3 years ago, the posts break off. BMW uses a rubber donut shapped washer that pushes on the post that goes through the metal fender and that holds the grill on the car.
So 2 relatively new grills were trash.
I thought about this and remembered my model train days when I would buy brass tubing from the hobby store. I had some around and was lucky I had the correct size to push on the posts and make them long enough to have some post on the inside of the fender to attach the rubber washers to. NOT, the BMW rubber washers have a spring steel disk inside them with the one-way teeth.
Push it on and it ain't coming off. That's why the posts break. I tried to drill the metal disk hole to a bigger size but the spring steel does not drill easily and the one way teeth catch on the drill bit and then it tares out of the rubber washer.
So once I got the brass rod on there, it was how was I going to hold them on. How about a washer and a tiny rubber o-ring. It took a good deal of effort to get this o-ring on the post so I am pretty confident it will stay. I will monitor after some miles.
I thought about putting threaded rod in the grills but was afraid they would break.
So here's a couple photos to explain this too complicated explanation. As a career photographer a photo is worth a 1000 words. Enough said.
 

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mr bump

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Brilliant idea!! I tried to remove one of mine, after one small post broke I gave up as it's an impossible task to remove them posts intact.
 
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m5bb

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I like the vacuum tube idea.
Could you not also cut a thread on the posts? I know they are plastic, but on some plastics it will work.
There's not enough post left if yours have broken off like mine did. Cutting those off and threading a new post was the next option.
I looked at that idea and it is feasible. Rods would be pretty small and threading them into the grills a little delicate but certainly doable.
A decent drill press would be mandatory to drill for the tap and there's not much depth there to thread in to. And unfortunately most taps are tapered so have good threads very deep in the grill body would also be difficult. Do they make flat/square bottom taps?
 

eriknetherlands

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Yes and it is often easiest to go to depth with the tapered tap and the finish with the square profile tap. Trying to do a deep hole with the straight sides tap is often a recipe for disaster.
True when talking about hard steels; taps can snap. Here in plastic I would be worried not for the tap but for the plastic post breaking. Hence I would use the taps that come in three stages; coarse, middle & fine and then finish with a flat top tap (do they translate to "Blind hole taps"? ).
 

m5bb

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True when talking about hard steels; taps can snap. Here in plastic I would be worried not for the tap but for the plastic post breaking. Hence I would use the taps that come in three stages; coarse, middle & fine and then finish with a flat top tap (do they translate to "Blind hole taps"? ).
Do you mean drill bits and start small then work up to the size needed for the tap?
 

eriknetherlands

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Mb55, I meant using 3 different taps. see the picture enclosed. it shows an m6 tap set. Right one of the 3 short M6 taps is the start=coarse. Middle is fine. Left is finishing tap. The longer one is intended for blind holes, it cuts an accurate thread in a blind hole up to 6 mm from the bottom of the hole. But anyway scrap the idea to use taps; I wouldn't go that route: I just measured the pins on my NOS side grille and they are just 4 mm. It kinda kills my own idea; to drill a 1,6 mm hole in a 4 mm pin nicely centered and straight is really difficult, then tap a M2 thread in them, (needing likely an investment in an M2 tap set) leaving only a 1 mm thin cylinder with female thread. It is becoming quite an effort, and so delicate that I would fear to end up with a broken pin.
Oh, and don't forget your working on a delicate, mirror finished piece of plastic.

I think i'd either use the original snap rings (or generic of the shelf ones, they're standard industry items) and just cut them in half with pliers if I ever want to take them off and replace with new.
Or i'd dive into cutting an M4 thread from the pin and use a plastic m4 nut with rubber washer on the inside of the fender. An M4 nut is also way easier to install inside the fender then a tiny M2 screw is.

I just also looked (for the first time) at the attachment of the grilles on my car; they just got rusted cross headed screws all the way through, splitting the bars in two..... I knew the chrome looked horrible from 10 feet away but never realized they were already broken.

You see, there is always a good reason to go for that elusive NOS part when it comes by....

O how I whish someone would CNC these out of steel or aluminium....(I know it has been done, I've seen a thread here on it somewhere, but it was a one-off)
 

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