Carbon Fiber Roof Saved! dreadful gel-coat fix

[M3MPH1S]

Originally Posted by lE92l

I had the same thing happen to my 2009 E92 M3. This thread helped guide me on what to do. THANKS TO THE OP

Unfortunately it sits outside for most of its life. I had it under bmw car cover, xpel clear bra on roof, and ceramic coating on xpel. Still with all that the gel coat failed. The good news is I was able to save it. I think my saving grace was the xpel. The clear started to bubble under the xpel. When I started to peal off the xpel the gel coat came off with it.

I got lucky and literally all of the gel coat came off with the xpel. Just came out like in sheets.

I then had a body shop just spray clear over it with the OPs instructions

Question - it looks like there was still splotchy yellowing on the carbon fiber after you removed the gel coat. How did the shop prep the carbon fiber to be cleared over? Did they just clean it with water and a mild detergent? Or did they do some polishing and/or wet sanding?

[DMA]

Originally Posted by CHE///MIST3

Awesome efforts with great results! I am amazed at how the layers just come off like that. when the gel-coat/clearcoat came off, did that take off most of the yellowness with it? I would have thought that most of the yellow would be embedded between the weaves of the carbon fabric, but from the looks of the layers you pulled off, its mostly in the clear coat/gel coat.

GM

Thanks!

Actually all the yellowness was the clear/gel coat itself. As it peeled off all of the yellowness came with it. What you see still on CF is just like a powder residue from the gel coat. That can just be cleaned off.

From the looks of it the carbon fiber was completely unharmed. Now that it has actual clear and not gel coat should last longer too.

I am still debating wether to do Xpel clear bra again but for now just coating it with CarPro Reload once a month. Plus its under bmw cover.

[DMA]

Originally Posted by M3MPH1S

Question - it looks like there was still splotchy yellowing on the carbon fiber after you removed the gel coat. How did the shop prep the carbon fiber to be cleared over? Did they just clean it with water and a mild detergent? Or did they do some polishing and/or wet sanding?

What was left was like a powder residue from the gel coat. Not sure what they used to remove it completely but little I took off was coming off with just water.

I would imagine just some grease/wax cleaner used for normal painting prep.

I know for the actual clear application there was I believe two coats then wet sand, two more coats then wet sand. Just like the OP explained. Not sure the total number of coats.

[Alexand3r]

Well the inevitable happened to me yesterday. All started with a little bubble on the front, over the windshield which I didn't even notice.
Went to the car wash and the pressure washer did it's job. And from then on, things escalated quickly. It peeled like it was hardly attached to the roof...
Under it, there was a ton of yellow dust formed by the gel coat.

I'll finish it of with a razor blade for the tough parts and it goes for a clear coat this week. Will keep you updated!

P.S. Here is also a little video of the peeling process. I just used a plastic(credit card) for the job.

[SoCalRPM]

Originally Posted by Alexand3r

Well the inevitable happened to me yesterday. All started with a little bubble on the front, over the windshield which I didn't even notice.
Went to the car wash and the pressure washer did it's job. And from then on, things escalated quickly. It peeled like it was hardly attached to the roof...
Under it, there was a ton of yellow dust formed by the gel coat.

I'll finish it of with a razor blade for the tough parts and it goes for a clear coat this week. Will keep you updated!

P.S. Here is also a little video of the peeling process. I just used a plastic(credit card) for the job.

This is the stuff of nightmares.

[CHE///MIST3]

Looking forward to the results ! It's nice that most of what actually turned yellow is gone....the clearcoat applied over the carbon laminate will enhance the blackness of the carbon weave.

GM

[Alexand3r]

Originally Posted by CHE///MIST3

Looking forward to the results ! It's nice that most of what actually turned yellow is gone....the clearcoat applied over the carbon laminate will enhance the blackness of the carbon weave.

GM

Yes, I definitely think that the yellow coloring will disappear now. It was all in the form of dust underneath and in the gel coat itself.
It's in the shop right now for the new clear coat. Will post results in the following days.

[Alexand3r]

Sorry for the delay! This is the result. MUCH better than before. The carbon fiber weave pops up much better and is more defined, also the yellowish colour is gone. Really happy with the result. So don't be scared when/if that happens to you, because it's for better.

[CHE///MIST3]

That looks phenomenal. There appears to be plenty of depth. Can you describe approximately what they did? Number of coats, sanding in between, etc ?

Enjoy the new roof!
GM

[Alexand3r]

As far as I know 3, but I'm not entirely sure about that.
I just know that the first layer just soaked into the carbon fiber and merely left any on the surface. I think they sanded the second one and then put the final layer. Again, not 100% sure, but I at maximum there is a fourth one.

[yoslow]

amazing looks brand new!

[E92friendly]

Originally Posted by CHE///MIST3

Awesome efforts with great results! I am amazed at how the layers just come off like that. when the gel-coat/clearcoat came off, did that take off most of the yellowness with it? I would have thought that most of the yellow would be embedded between the weaves of the carbon fabric, but from the looks of the layers you pulled off, its mostly in the clear coat/gel coat.

GM

Honestly the yellow resin doesn't really catch between the weave as long as it's prepped right and likely using scuff pads would clean it all up. Wet sanding helped to in preparation.

[NeverL8]

Looks really good guys! Anyone put clear xpell film over their new cf roofs?

[Cbozz]

Originally Posted by Alexand3r

Sorry for the delay! This is the result. MUCH better than before. The carbon fiber weave pops up much better and is more defined, also the yellowish colour is gone. Really happy with the result. So don't be scared when/if that happens to you, because it's for better.

that looks very nice!

[jvictormp]

Originally Posted by Alexand3r

Sorry for the delay! This is the result. MUCH better than before. The carbon fiber weave pops up much better and is more defined, also the yellowish colour is gone. Really happy with the result. So don't be scared when/if that happens to you, because it's for better.

Great!!!

Did you/they need to take off the windshield? Cause I've got a bubble over the windshield too.

[suprtofy]

I’ve purchased an e92 M3 with the carbon roof already spray painted gloss black.. i know I can’t just use a paint stripper because of the high risk it damages the carbon. Anyone had to deal with a painted carbon roof before ? Any help is appreciated !

[E92friendly]

Originally Posted by jvictormp

Great!!!

Did you/they need to take off the windshield? Cause I've got a bubble over the windshield too.

They were able to rope the glass seals avoiding removal

[E92friendly]

Originally Posted by suprtofy

I've purchased an e92 M3 with the carbon roof already spray painted gloss black.. i know I can't just use a paint stripper because of the high risk it damages the carbon. Anyone had to deal with a painted carbon roof before ? Any help is appreciated !

I dont know what to tell ya other than have it replaced. Because it is painted it would be very difficult to judge how close you are to the carbon when stripping it. It would be very very hard and twice the time to remove carefully

[PYE46M3]

man this stuff is scary to read.

so a tiny rock chip in the roof can cause the gel coat to start to peel off?

is there any benefit to clear coat a roof in excellent condition to add more protection to the gel coat.

[E92friendly]

Originally Posted by PYE46M3

man this stuff is scary to read.

so a tiny rock chip in the roof can cause the gel coat to start to peel off?

is there any benefit to clear coat a roof in excellent condition to add more protection to the gel coat.

As far as I know I don't recall rocks able to start chipping the gel coat. It's the resin that's between the gel and carbon that becomes weak from the sun rays and causing a peeling point on the roof. Not rocks. When you start to see a yellow tint that's no bueno it's the resin becoming weak.

[Rackeu]

Originally Posted by SoCalRPM

This is the stuff of nightmares.

I tried using a credit card and a plastic razor blade, it worked just fine but it was taking a long time. I then used compressed air behind a tab of skin to "push" up under the sheet and was able to get it all off very easily in very large sheets. See below.

This link is aspirational and it does not work this easily BUT: using compressed air under the edge while teasing a peel lifts it off in large sheets and works very well.

[Mpow-wow]

I just pressure washed my roof and the old polyurethane coating came of so easy! Now to get someone to re-clear it. 👍🏻