First off, sorry about the size of the pics
So I found a CF trunk lid on kijiji last week, it was pretty cheap for what it is IMO, $225 CDN (that's roughly $165 USD) So I bought it.
However its not perfect. I think its totally repairable, I just want to get some opinions on how to go about it.
First off, the Gel Coat on the exterior is 98% mint (I deduct 1% per dinged up corner)









In the next pic you can see the black peeling on the outer edge. I'm not sure if this is just paint or if its gel coat. I THINK it's paint. Just sand and touch up?


The next 2 you can see the worst of the dinged up corners.


Its hard to see but if you press down on the very tip the crack does open up. I was thinking I could just get some epoxy in there. I think I have some 30 minute epoxy from my RC stuff. My plan was to get some in there and gently apply some clamping pressure while it cures.
Could I use the same epoxy to rebuild the corner tips? The stuff I have is sandable, and paintable, that much I know


Finally, along 2 of the edges (along the bumper edge for about 8", along the rear window edge for about 6") its been rubbed pretty raw. Again, thought maybe I'd use some of that same epoxy and then gently sand it into shape.




The whole piece does have a slight black fade around the outer edges. this should help me blend any repairs I do. I just want to make sure I'm on the right track before I do it.

And yes, I'll be drilling holes to mount the high rise spoiler. Maybe not right away. I'll take my time and make a template for the holes off the stock trunk lid.
Whats the best way to drill CF?

Thanks!

 

are you going to be doing it yourself? i would recommend to take it to a custom body shop to help out as carbon fiber repair can get pretty involved

 

Doing it myself.
I could probably buy a brand new CF trunk lid for what the body shops around here would charge me. Last thing I got done was a bumper respray and it was $500, they'd see my wallet coming a mile away with a carbon fiber job

My hood is in rougher shape, I'll likely end up replacing it over getting it repaired.

 

For the first paint or gel coat question, I can't really tell what I'm looking at.

For the corners: first I'd get a better epoxy. Something with a 24 hour cure. You don't need it to quick set, and it would be difficult to work with, because I'd suggest to get a syringe and inject epoxy between the layers. Then clamp it up and leave it.

For the edges, that will be harder to fix. Surface prep is key. Lightly sand and use alcohol to clean it up, then apply. You're just making sure exposed fibers are covered. Then touch up the gel coat, then paint (if desired). The risk is that if the epoxy doesn't adhere it'll crack and flake off, looking worse than before.

 

Seems easy enough.
So the slower setting epoxies will end up being stronger in the end?

For the surface prep, I've got some wax and grease remover, this would suffice, no?

For the gelcoat vs paint chipping off. Its flaking off very thin, like paint, wouldn't gelcoat typically come off much thicker and expose bare fibers under it?

 

Yes, definitely. You'll also get MUCH better adhesion with it, which is what you're really looking for here.

I'd do some mechanical work to get anything embedded out. Just because you're doing this on the cheap doesn't mean you should be lazy too. No matter what you do, use an alcohol wipe to get chemicals and debris out before you epoxy.

Not necessarily. When you layup a laminate, the fabric is soaked in resin (usually epoxy for carbon) so when you expose bare fibers you've gone through both gel coat and resin. The gel coat can be fairly thin just to protect the resin from the environment. Yes, they can be liberal on gel coat for car parts and such where the carbon is mostly just for show. On the backside, it's probably thin or non-existent. Regardless, touch-up paint should be fine.

 

Yeah, I figured I'd give it a light sanding. I was referring to clean up, in lou of alcohol. I've always just used this wax & grease remover for clean up before paint. I used to get it at an autobody supply store, now Canadian Tire carries it though

The chipping is on the back, and its flat white underneath, no sign of fibers or anything.
Also, this trunk lid, like my hood, appears to be mainly fibreglass with a CF exterior layer