Carbon Fiber Repair Inside!
#1
Carbon Fiber Repair Inside!
Seeing as these cars are getting older and people have been inquiring lately as to how to repair these pieces I decided to repair and document some carbon trim repair. If anyone needs any help feel free to PM me as I have been working with fiberglass/carbon repairs for @ 20 years. Thanks for looking!
I have OEM carbon trim and yes, after @ 14 years, it will have issues. My door panels are excellent, save for some yellowing. I find the issues to be on pieces with hard contours. The upper horse shoe around the radio surround is very susceptible to cracking where the bends occur.
It's worth noting that the OEM stuff, as nice as it is, is still an overlay and not pure CF. If anything was full carbon it would cost $$$ so most companies take a plastic piece and it gets overlayed with carbon sheet and epoxy. Over time the carbon will try and delaminate from exposure to heat, time, general use, etc. Also, the factory finish coating is not UV resilient and will 100% yellow over time. This is even true for the CGT as noted in many complaints to Porsche.
While John had good luck with re-clearing the piece, clearcoat is very thin and I'm sure he sat there and applied 15-20 coats to get a nice buildup. The proper fix is to use epoxy resin then clear. This is also how it's produced (many times less the clear application) and will give the best results. Stay away from polyester resins as the epoxy is a superior product for this application and what is used in production. New epoxies are UV resistant and very, very hard.
Below I will show a quick repair I did last night to my upper dash piece. I will be re-doing most of my trim just because I am looking for things to do
1. Take the piece off the car and analyze what needs to be done. If the piece has delaminated from its base, mix some epoxy and use some toothpicks or other methods to get the epoxy under the piece and clamp it. Once it sets up you can address any cosmetic issues to the face of the panel.
2. My upper trim had numerous cracks along the contours and small chips in other areas easily felt while rubbing your fingers over the pieces. I start by using 80 grit paper on the really bad areas and slightly feathering the cracks out to the unaffected areas. Next I work my way up over the prior areas and entire piece all the way up to 400-500 grit. Sand each area with the new paper until the prior marks have been removed. Your end goal should make the piece look perfectly matte with only little sanding marks visible.
*Note that some cracks may be deeper than others and if they go all the way to the substrate to the carbon it will require removal of most of the factory epoxy in that area. For this piece, I did not sand to the base as it was very late at night and I needed to get this piece done rather quickly to get my car back together. Additionally, the repairs below achieve a 95% perfect finish without having to spend additional days on the repair. I also try to maintain most of the integrity of the OEM parts, so the least amount of work needed to repair, the better in my eyes.
Below you'll see pics of the sanding process and how deep some of the chips, scratches were. These were very visible and felt if you rubbed your hand over them.
2. Once the sanding is completed I go over the piece with alcohol and prep it for the epoxy repair. For the repairs I am using a commercial 2-part epoxy. For this, it's best to use an ultra clear product for a perfect finish. Epoxy should be (relatively) self leveling and I use a foam brush and a synthetic bristle brush as needed to make sure all the edges are covered and contours are wrapped. Epoxy covers thick, so it's much more suited to this than just traditional clear coat. It also adds a tremendous amount of strength and rigidity to the final product which in turn will prevent future cracking from any flexing. It still will have some slight flex to it, but most of the original flimsiness is removed which is ideal.
Here are pics once epoxy is poured. It wets out very well. This is just one wet coat.
Note the above finish is nearly perfect. Below you'll see the crack that was very visible in the first sanding photos is nearly gone. It's clarity is now 95% perfect with only a slight line visible only depending on how the piece is looked at. All the other imperfections are gone, including (most of) the yellowing that appears in the pieces due to age/time/sun.
And below is the final piece, about 10 hours later, in the sun. I still have final sanding/polishing to do, but you can see the results are dramatic and the depth is 100x better than it was when the car was new. The product used adds many mills of coverage and considerable depth.
Thanks for viewing! I have been repairing/working with fiberglass and carbon fiber for 20+ years and feel pretty comfortable with it. Should anyone have any questions send me a message.
Thanks!
I have OEM carbon trim and yes, after @ 14 years, it will have issues. My door panels are excellent, save for some yellowing. I find the issues to be on pieces with hard contours. The upper horse shoe around the radio surround is very susceptible to cracking where the bends occur.
It's worth noting that the OEM stuff, as nice as it is, is still an overlay and not pure CF. If anything was full carbon it would cost $$$ so most companies take a plastic piece and it gets overlayed with carbon sheet and epoxy. Over time the carbon will try and delaminate from exposure to heat, time, general use, etc. Also, the factory finish coating is not UV resilient and will 100% yellow over time. This is even true for the CGT as noted in many complaints to Porsche.
While John had good luck with re-clearing the piece, clearcoat is very thin and I'm sure he sat there and applied 15-20 coats to get a nice buildup. The proper fix is to use epoxy resin then clear. This is also how it's produced (many times less the clear application) and will give the best results. Stay away from polyester resins as the epoxy is a superior product for this application and what is used in production. New epoxies are UV resistant and very, very hard.
Below I will show a quick repair I did last night to my upper dash piece. I will be re-doing most of my trim just because I am looking for things to do
1. Take the piece off the car and analyze what needs to be done. If the piece has delaminated from its base, mix some epoxy and use some toothpicks or other methods to get the epoxy under the piece and clamp it. Once it sets up you can address any cosmetic issues to the face of the panel.
2. My upper trim had numerous cracks along the contours and small chips in other areas easily felt while rubbing your fingers over the pieces. I start by using 80 grit paper on the really bad areas and slightly feathering the cracks out to the unaffected areas. Next I work my way up over the prior areas and entire piece all the way up to 400-500 grit. Sand each area with the new paper until the prior marks have been removed. Your end goal should make the piece look perfectly matte with only little sanding marks visible.
*Note that some cracks may be deeper than others and if they go all the way to the substrate to the carbon it will require removal of most of the factory epoxy in that area. For this piece, I did not sand to the base as it was very late at night and I needed to get this piece done rather quickly to get my car back together. Additionally, the repairs below achieve a 95% perfect finish without having to spend additional days on the repair. I also try to maintain most of the integrity of the OEM parts, so the least amount of work needed to repair, the better in my eyes.
Below you'll see pics of the sanding process and how deep some of the chips, scratches were. These were very visible and felt if you rubbed your hand over them.
2. Once the sanding is completed I go over the piece with alcohol and prep it for the epoxy repair. For the repairs I am using a commercial 2-part epoxy. For this, it's best to use an ultra clear product for a perfect finish. Epoxy should be (relatively) self leveling and I use a foam brush and a synthetic bristle brush as needed to make sure all the edges are covered and contours are wrapped. Epoxy covers thick, so it's much more suited to this than just traditional clear coat. It also adds a tremendous amount of strength and rigidity to the final product which in turn will prevent future cracking from any flexing. It still will have some slight flex to it, but most of the original flimsiness is removed which is ideal.
Here are pics once epoxy is poured. It wets out very well. This is just one wet coat.
Note the above finish is nearly perfect. Below you'll see the crack that was very visible in the first sanding photos is nearly gone. It's clarity is now 95% perfect with only a slight line visible only depending on how the piece is looked at. All the other imperfections are gone, including (most of) the yellowing that appears in the pieces due to age/time/sun.
And below is the final piece, about 10 hours later, in the sun. I still have final sanding/polishing to do, but you can see the results are dramatic and the depth is 100x better than it was when the car was new. The product used adds many mills of coverage and considerable depth.
Thanks for viewing! I have been repairing/working with fiberglass and carbon fiber for 20+ years and feel pretty comfortable with it. Should anyone have any questions send me a message.
Thanks!
Last edited by s65e90; 07-21-2021 at 08:16 PM.
#7
Trending Topics
#9
Go for it... It's hard to screw it up... If you don't like it on the first try, just sand again and re-apply. Stop when you love the results. CF is very forgiving to work with.
- Just make sure to tape off the areas you do not want the resin to stick to.
- Just make sure to tape off the areas you do not want the resin to stick to.
#11
If it were that easy everyone would be doing it. While not rocket science it does take some work and time. And if the cracks are all the way through care must be taken to ensure the carbon cloth isn't disturbed.
#12
I think most people don't do it because they think it's really hard. If they totally screw the pooch, they can sand off the CF too and re-apply. People think CF really expensive... it's about $40 a yard - that's enough for the entire interior of a TT. ... and if it's not quite perfect - it still looks better than the cracked one.
#14
The grit depends on how much you need to fix the resin. Work your way up and, when it all looks good, end with 1000 grit and spay with automotive clear coat.
If you want to be sure your repair doesn't turn yellow over time, the clear coat is a must.
Edit: Always wet sand... you don't want to be inhaling CF dust. (and the sandpaper lasts forever)
If you want to be sure your repair doesn't turn yellow over time, the clear coat is a must.
Edit: Always wet sand... you don't want to be inhaling CF dust. (and the sandpaper lasts forever)
Last edited by Slider; 03-26-2017 at 11:39 PM.
#15
Start with 80 and work your way up to around 6-800. No need to go to 1000 and I wouldn't as there's no reason to and the clear needs to bite into something so I would stop around 800.
Epoxy resins have also come a long way since the trim was made for these cars and many are very UV stable by themselves. Clear coating it will ensure it will last for a long time but depending on what resin products are used it may or may not be required.
Wetsanding will keep dust to a minimum as well as not clog up the paper too much.