GK fairing cracked. Plastic Repair.

[Redman]

GK fairing has had terrible obnoxious buzzing at certain RPM range, and annoying buzzing at other RPM range.

I have found these cracks in the inside portions.
I tried jamming some orings in there to keep the edges from rattling on each other, just as a test, and pretty much proved these are the source of the noise.

Now have the fairing off and in my work area. ANd got these pictures.

ALso noticed that if grab the fairing by "A" and "B" (as marked in photo) and pull apart the crack opens up more, if push together then the crack pretty much closes up.

I do recall previous discussion on here about making a slurry with a solvent (toluene?) and ground up plastic.
Trying to find where I can get some of that toluene.
And how to determine what plastic to use.

ANybody have any idea if that is good approach for this?
Maybe I need something to "stitch" it together in a few places.

I do recall years ago, someone (Dale RustyBronco?) cut up a fairing like this and shipped halfway around the world (SouthAmerica?) and then someone glued it back together.

 

[Burque73]

As suggested by Steve, I dissolved some ABS pipe pieces in a bit of acetone to make a slurry. It worked very well on the vetter fairing. I applied some fiber tape first, like drywall repair type mesh tape, then brushed the slurry over it.

 

[Redman]

Acetone.
THanks Roger.

 

[Grimly]

MEK (methyl ethyl ketone) is another useful solvent for ABS pipes - used over here for PVC and ABS pipe welding. I'll probably be using it soon to patch a crack on a side panel.

 

[Steve]

If you don't want to make your own slurry, you can get ABS cement in the plumbing section at the hardware store. There is also a plastic repair product that is available at the auto parts store, but I don't remember the exact name at this time. I think it was either Rustybronco or Chuck Hahn that has mentioned that one.

Whichever product you use, be prepared to do some work. Pull at your "A" and "B" points to spread the crack, dribble your glue (slurry, epoxy, whatever) in the crack, then push them back together and spread some more glue on one side (top or bottom) of the crack. After a few hours, it should have set up a bit, turn the fairing over and apply glue to the other side. Be careful, the glue will sag and run a bit before it sets, so plan accordingly. Don't apply it to anything vertical, horizontal surfaces only.

Also, don't be in a big hurry to get it mounted back on the bike. Let it set at least a week or so before putting any stress on it. Since your weather probably isn't any better than ours right now, there probably aren't any rides on your calendar, so it shouldn't be much of a problem.

.

 

[Buffalo Bill]

You can buy epoxy for plastic, very EZ to use. This was recommended by nvr2old, maybe the best motorcycle body guy on this site.

 

[Guest]

i second the "plastic welder" 2 part epoxy stuff, I think it works better than slurry. Messy though, either way count on some cleanup with a die grinder or dremel or something....

 

[Guest]

I'd like to find something that I can live with. I tried plastic welding, and it didn't hold. The only thing that has held so far, is some JB Weld that was a bit thin when mixed. It has held a makeshift tab on my side cover for over a year.

 

[Burque73]

I also used some fiberglass mesh and resin with some success on the fairing. It didnt hold too well on a side cover though.
I think the key in whatever method/ product used is good prep. Roughing up the repair area, cleaning well and allowing, as mentioned, ample time to cure before any stress on the repair area.

Dave, can you heat up or chemically soften and bend some material, like ABS, to conform to the areas subject to the most stress and bridge the repair?

 

[Grimly]

Dave, can you heat up or chemically soften and bend some material, like ABS, to conform to the areas subject to the most stress and bridge the repair?

Yep, certainly can. A good hot air gun will do the job, no problem.
I'll probably have to do that with my side panel just to make sure, as it cracks at the top hook-over tabs. A previous repair with fibreglass lasted only 25 years, which is bloody disgraceful.

Another technique for plastic welding involves sinking a wire tie across the crack, every few mm or so, then going along the whole crack as normal. There's even a tool for it, but the pro-grade one isn't cheap. The diy version is just the humble soldering iron and some wire snippets cut and shaped at each end into a figure-8.

 

[Burque73]

Thanks, Dave, for confirming that works.

Just another thought, before I poured the "slurry" I applied some acetone to the repair area to clean and soften it a bit. I suspect that helps create a better bond.

 

[Redman]

Good point, Guys, Thanks.

I think I will want the more of a solvent based idea, so it softens up the base edges and then solidifys back together.

Good idea about having the work area more horizontal. I would have though of that after stuff was slopping down.

Have limitted access to the backside of the cracks (inside the faring), but will see if I can find some plastic material and make some to fit inside. THe cracks are mostly along corners.

 

[Redman]

................... ABS cement in the plumbing section at the hardware store. .
.

Will look. Thanks.
Is that different than the typical cement for PVC plumbing......?

 

[Steve]

Will look. Thanks.
Is that different than the typical cement for PVC plumbing......?

Yes. PVC glue is not the same as ABS glue. Some glues claim to work on both, but a dedicated ABS glue will be best.

I would also suggest Roger's idea of applying a bit of acetone as a "primer" to prep the plastic a bit.

.

 

[MR.G]

What I have done is used a standard soldering gun. Let it get up to temp then gently push it into the start of a crack, ensuring it melts both edges of the crack, following with exact same pieces of plastic for your "welding rod" . Works very well. The key is to get the "exact same" plastic as the filler/ welding rod. Go to a wrecking yard and look for the plastic. Should be easy to find. Not all plastics weld to different plastics, they crack pretty easy if your using two different plastics.

 

[Burque73]

What I have done is used a standard soldering gun. Let it get up to temp then gently push it into the start of a crack, ensuring it melts both edges of the crack, following with exact same pieces of plastic for your "welding rod" . Works very well. The key is to get the "exact same" plastic as the filler/ welding rod. Go to a wrecking yard and look for the plastic. Should be easy to find. Not all plastics weld to different plastics, they crack pretty easy if your using two different plastics.

That sounds very interesting. Would you make two passes with the iron or melt the new material into the weld in the same pass?

If this is similar to what you're describing, I'd really like to try it.

https://www.youtube.com/watch?v=xnrpxDqn2z4

 

[2BRacing]

…….I do recall years ago, someone (Dale RustyBronco?) cut up a fairing like this and shipped halfway around the world (SouthAmerica?) and then someone glued it back together.

Yes Dave, it was RustyBronco (Dale) and Chuck Hahn that cut a Vetter fairing up for transport in smaller parcels and shipped it to South Africa, for member Matchless. I thought I had saved the thread that Matchless wrote on putting the fairing back together, but now I cannot locate it. Maybe your or someone else's skills in retrieving old threads is better than mine, and you find it!

Good luck with your repair!

 

[MR.G]

That sounds very interesting. Would you make two passes with the iron or melt the new material into the weld in the same pass?

If this is similar to what you're describing, I'd really like to try it.

https://www.youtube.com/watch?v=xnrpxDqn2z4

I did both in the same pass, but you could do a second pass with the filler plastic just make sure you get the crack and the filler rod nicely melted so they mix. Either way is fine. If you can do both sides even better.

 

[Gorminrider]

I've been using a similar method aka soldering iron...with a "widish" tip, push it across the crack, "upwards" or "downwards" to make a little bridge. This will hold your bits together..then, if you want to melt material into it or if you want to add jbweld after, thats ok too....

To hide the crack from the outside, cosmetically, is a bit more involved -ideally, cut a slight vgroove in to fill with the material of your choice....I put masking tape both sides to isolate the fix from accidental scratches while I fair it. Likewise, if you want to prime and paint it without redoing the whole thing....

JBweld now makes a two-part plastic cement that is more flexible than their good ol epoxy. I'm experimenting with it but so far the ol stuff seems stronger. People have said that epoxy is too stiff and a fix rebreaks around it but on a place that is supposed to be stiff and strong, I don't even understand the complaint...

ABS plumbers cement can work too but I've depecrated it in favour of the tack-welding and jbweld...it is harder to fair and paint and takes awhile to adequately harden.

 

[Redman]

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The soldering gun method seems good and strong, but I think will exceed my manaul dexterity.