# DIY: e46 painted rear diffuser



## beemerb0y (Apr 25, 2007)

I really like the CSL style carbon fiber rear diffuser, but given its price tag (at least $200) and then getting it painted to color-match your car (another $100-150)..and seeing many that don't fit like OEM (have gaps and stuff) I decided to try something new that hasn't been done before on our cars. I got the following idea from previously owning a C5 Corvette and we used to do the same thing.

Difficulty level: 2/10

You will need:
1) Your OEM diffuser (I purchased another one used from a forum member so I can always have my factory one to put back if needed)
2) One can of Duplicolor universal black paint
3) Blue painter's tape
4) 600 grit and 1000 grit sand paper. One 8.5x11" sheet of each is enough.
5) Exacto knife, razor, or scissor.
6) 2-3 hours of your time. The prep is the longest and most important part

Here are the instructions:
1) Remove OEM diffuser (instructions can be found http://www.m3forum.net/m3forum/showthread.php?t=192259&highlight=diy+diffuser ) 
2) Thoroughly wash it with Dawn soap.
3) Mask off the border of the diffuser part that you want to paint, then cover up any part that you want to leave unpainted. This part takes the longest because the edges will be curves. Use an exacto knife. I used scissors and it didn't come out perfect.
4) Using 600 grit sand paper, wet-sand the part you will paint. Sand just enough to scuff it so it doesn't look shiny. Essentially you are removing most of the clear. The best surface for painting is your old paint. Do NOT primer the diffuser.
5) Go over it with 1000 grit sand paper to make it smooth.
6) Clean off with water then with alcohol. Make sure it dries and has no dust on it.
7) Go outside when the temperature is warm (at least 65-70*F) and lay it on the ground or work bench.
8) Spray it with a tack coat. Just go over it lightly and wait 5 minutes. This gives the surface a sticky coat for the paint to stick on to. It does not cover the entire surface, meaning you will still see almost all of the OEM color.
9) Now on to heavier coats of paint. Spray and leave 10-15 minutes to dry between coats. I don't know how many coats I did, but I finished the can at the end of the project. 
10) Remove tape, install diffuser, look back and admire.

I didn't take pictures in the process, but I think they are pretty self explanatory. Here are my end results. I would redo it using an exacto knife this time to round off the tape on the edges. Overall, I am very pleased and I think it looks great and is well worth the money.

Pictures:

Removing the OEM diffuser will amaze you. So much dirt and crap behind there:

























Duplicolor Universal Flat Black paint









Buy this spray gun handle- $4- makes it easier to hold the can and prevents overspray.


































































If you guys have any questions, feel free to post them here. Good luck. :thumbsup2:


----------



## scotte36 (Jul 11, 2006)

Man i couldnt imagine attacking a car that new and the price of it with a can of flat black.


you should have rounded the corners a bit neater looks to be sharp turns .


as long as you like it thats all that matters


----------



## Chiefsfan (Oct 15, 2020)

I painted mine.. I didn't even take it off the car


----------

