Repair, prep, and paint damaged ABS motorcycle fairings

Anything goes in the world of fiberglass and plastic



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PostPosted: Sat Sep 12, 2015 3:12 pm
This is my first attempt at any kind of body work. I have read through several articles and forum posts, including skullsession's thread on reworking ABS fairings and feel that I learned quite a bit, mostly that I know nothing.

So, I am working with an ABS plastic fairing that has already been repainted once. From top to bottom, I see a top clear coat, the red base coat, a white primer, the blue OEM base coat (probably a clear on top of that), then bare ABS.

Since the rash had already gouged down to the ABS, I started there with a dry sand using standard woodworking 220 grit to try and smooth it out. Then, in an amateur move, I tried a wet sand with the same 220 grit on the whole fairing. The paper didn't hold up for long so I did wet sand with proper 3M wet-dry 400 grit. I am unsure how many layers should be removed so maybe I got a little carried away. I understand I must at least get rid of all shiny parts. Here's where I am so far:
fairing_prep_001_left_upper.jpg


So how many layers should I be removing? Should I only sand down to ABS in the damaged areas like ScottB says here?

Some later posts in that thread suggest removing everything down to the bare plastic. Is this the better approach for my application, considering it's already been repainted once?

I have Urethane Supply Flex Filler to fill the deep gouges. Does anyone know if this will require complete paint removal, or does it work over paint? Looking for an answer, I found the plastic repair book and on page 17 they say to use their hardset filler on rigid plastics like ABS, which is annoying, since their how to guide and video on fairing repair says to use flex filler. I'll probably call for an explanation.



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PostPosted: Sun Sep 13, 2015 11:29 am
Well I learned that I already made at least one mistake. I did not use a wax and grease remover before sanding. I suppose this means that whatever wax and grease was on the surface before sanding is now embedded in the sanding grooves of the paint and plastic. Can this be corrected? Can I use a wax and grease remover at this point and fix it? I did use dawn soap in the spray bottle and the sandpaper soak cup but I'm not sure how much that helped.

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PostPosted: Wed Sep 16, 2015 6:15 am
I was waiting on someone with more experience to chime in...but since they haven't....

I'd just wash it up with soap and water and then use the degreaser. You'll probably be fine. Either way, that's about all you can do now.

Personally, in my limited experience, I don't like the looks of the exposed layers....ABS, blue, primer, red, etc. On my project, I found that those edges are what lifted when I primed them. If it were me, I'd be taking that piece down to abs and starting fresh. Or...do your body work and prime it knowing that you might have issues to address. I ran about a 50% success rate when it came to fixing these lifting portions. The other 50% I ended up going back in with sand paper and starting fresh from ABS.

The damage is kind of hard to find in this pic. Maybe it's just deep scratches...or maybe you've already sanded it out? I would just use normal body filler if there are still deep gouges that need filled. Should be easy enough. I wouldn't even worry about flex products if that ABS is as sturdy as that on my bike.

Are there other pieces from this bike that need work?



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PostPosted: Mon Sep 21, 2015 9:48 pm
Hey skullsession thanks for the response and thanks so much for documenting your project. It was very informative.

Ok, so this project has been on hold but I will mix some high concentration dawn and wash it down before I do anything else. I have been around to local auto parts places but haven't found any wax and grease remover for auto body work yet. I found a thread where someone else started sanding without using wax & grease remover. Some suggestions for easily accessible products for pre-sanding wax and grease removal are naphtha, mineral spirits, alcohol, simple green, vinegar, and dish soap. I found more suggestions for dish soap and alcohol/water mixture here and here. After the dish soap wash, I am leaning towards an isopropyl alcohol rinse, since it will not leave any contaminants and will not harm the ABS. Unless anyone has a better suggestion?

The damage on this fairing occurred where the black ABS is exposed. Here it is in more detail:

fairing_prep_003_left_upper_gouges.jpg


Obviously this isn't the first time it's seen damage with the scratches filled with white primer. I am not sure what the best way is to get that primer out? Should I use some kind of sharp scraping tool? Something like these?
Image


I am a little concerned about what happens if I continue sanding to get the scratches smoothed out, that too much material would be lost and the fairing will become fragile. This is why I was planning to use the flex filler to build it back up some.

I agree that it would be best to remove everything down to bare ABS so the primer has a uniform surface to adhere to. I started thinking this way when I read this article: http://faq.ninja250.org/wiki/Plastics_r ... ABS_cement

I think he makes a good point about keeping a uniform medium of ABS as opposed to using some other filler material. I picked up a couple sheets of black ABS so I think I am going to mix some shavings with acetone and use that as filler.

There are other fairings that will need work as well. I have the right upper, the nose, 2 lowers, the tail fairings, and the tank. I decided to start with this one since it had suffered the most damage during the fall. I picked up some 220 grit wet-dry sandpaper to help remove all this paint. The 400 was taking way too long.



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PostPosted: Wed Sep 23, 2015 1:07 am
I'm no expert, by any means, but I've repaired and painted several sets of motorcycle fairings in the past.

As far as the damaged area - I wouldn't worry about the primer that remains in those deep scratches. If the structural integrity (no splits / cracks through the fairing) is still good, just fill the gouges.

I've used normal Evercoat polyester filler in the past with no issues whatsoever.
If it were me, I'd scuff the damaged area a bit with 80 grit (no major effort or sanding here - just giving good bite for the filler).

Mix and spread the filler on that spot. Don't worry about being perfect - make sure you spread enough to be higher than the surrounding area - you'll be sanding the majority of the filler off anyway.

As for the rest of the fairings...if the existing paint / clear is in good shape, a good scuff will do the trick.

Hope this helps.

Also - for cracks - you EASILY plastic weld them back together using a cheap solder gun. Just heat the gun up and "stitch" the cracks together using the iron.



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PostPosted: Mon Sep 28, 2015 2:09 pm
partly I agree with ctandc, but if you want high quality repair and that it holds up really for a long time, i mean for many years, you need not just a good technology but also a suitable materials. With ABS is always difficult to work, espesially if we speak about welding. Material is veeeery sensitive and loose it's form from any too long heating. There are no sense to use a 3M Henkel, Fusor and etc. Once I had a "funny work", there are was no chances to repair it with some "glue".
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