Does anyone have experience installing the rear carbon diffuser on here? I got a new one as mine was a little scuffed up.

Taking it off went fine, I unscrewed the 4 torx bolts and then started popping out the trim tabs. Each trim tab has a metal clip pictured below that pops off. I'm not sure if these metal clips were behind the bumper trim or if they insert into the little slots for the tabs to pass through.

This is one of those issues that is hard to explain unless in person so if I'm not being clear on anything let me know. I'm at the point that I don't know how you would do this without taking the entire rear bumper off in order to get access to put the metal clips on.


Carbon Tab and Bumper Slot

I dont think these go in this direct, I think they go behind the bumper trim piece.

Metal Clip

Metal Clip

 

a paint/body shop can buff up the old diffuser and make it look new. They might help with install also.

 

The diffuser that came on the car would need someone that specializes in carbon to properly redo it. It was easier to just get a new one while supplies last (last I heard 7 left worldwide).

Just find it interesting no one I have talked to knows how to properly install. I'm 99% sure the rear bumper cover needs to come off, but I will post to confirm that once I have more information. You could very easily secure the diffuser without going to this trouble, but I like things done the right way.

 

Hi M3TZ,

You already have the bumper off, but for anyone else out there....

4 star bolts, one per side on the fenders, two on the trans cooler. Remove screws, set aside. Grab out-bound vertical molded carbon fiber of the diffuser by trans cooler and give a firm and deliberate tug straight back. Do not pull at an angle up or down. Inspect trans cooler brackets. There should be two spring clips that receive the screws you just removed. If they came off with the diffuser, reinstall. Might also want to inspect the trans cooler bracket and re-adjust if needed. The PO of my car appears to have backed this into a curb and bent the bracket up just a skosh (which is when he likely damaged the diffuser and replaced with an aftermarket). A piece of wood and a little love realigned. This is aluminum and does not need much force to straighten.

To install the factory part, line up the lower tabs to ensure they are below the trans cooler. The upper tabs are a friction fit. Once aligned, punch the arc portion of the diffuser in the center. Work your way to the outside if needed. Mine did not. Just two firm punches (fleshy part of fist by pinky) and the entire piece snapped into place. Gotta love factory parts.

M3TZ, that clip in your hand appears to be a spring clip that goes in one of the pockets in the bumper or possibly on the trans cooler. Mine did not come out when I removed my diffuser. Look at the pockets and see if one is missing the clip or if it will fit at all. You can expand the clip and press it back in place prior to putting the diffuser on. If you only have one place to put the clip, I'd put it in the middle, but I don't think it goes there. If you can't figure it out, let me know. I can pop mine off and re-examine.

Lastly, with the diffuser off, its a great time to polish the tips as you have full access.

It took longer to do this write up than to replace mine. Don't over think it, carbon is very, very strong (it just doesn't like being backed into curbs at Cars and Coffee). John at MA Carbon helped me source mine. He is a great guy. I wonder if he would consider repair work?

Happy motoring.

 

Appreciate you taking the time to reply, I figured someone had some experience doing this. However, there were actually 12 metal clamps (as mercedes defines them) on each tab that slides into the bumper as well as the two support brackets that bend down. Each one of these clamps popped off when I pulled the diffuser out after removing the screws. Seems to me either yours stayed behind the bumper and allowed you to release them, which seems unlikely given they have a tooth and need to be released with a lot of force or someone had already removed the diffuser and not gone to the trouble of putting them back.

 

It's possible the PO did not replace them.

Those barbs look pretty aggressive. You could look at the tabs and see if there is a "tell". If so, you know what needs to be done.

When I installed the factory part, there was positive engagement with something on the top rim of the diffuser. I assumed it was pinch clips or possibly the molding in the bumper panel. That said, the diffuser shows no signs of movement at speeds that may be at, below, or slightly above the posted speed limit while being followed by a friend listening to the exhaust note.

 

Good to know you've "tested" that mounting method . If I do end up having someone pull the bumper cover to replace the clamps I will do my best to document for future reference here.