Ways to fix split in fairing

**sibrit** · 16th July 2013, 11:26

It's a known problem with the Ducati ST's that if you don't take care when removing the upper side fairings that the PVC can split in a couple of places. I've not taken them off myself until now but the RHS already has a crack. Since I don't recall when it might of appeared I can't really point a finger at any particular garage, so I'll let it slide and move on.

After a quick check online, I realised that $1000 for replacing it was not worth it, so before I put the original fairing back on, I wanted to see what I could do to repair or limit further damage. In the past, when my old KLE400 fell over in strong wind and landed on a rock, I slapped some of that 2-part fiberglass resin and hardener over the inside to hold it all in place, but then I didn't care about the looks. For the Ducati, I might want to do something different.

Any suggestions?

**Maha** · 16th July 2013, 11:56

Thermo/plastic weld?...I had one repaired on a Yamaha I onced owned, by a competent paint/panel man.

**Metastable** · 16th July 2013, 12:08

If it is a small crack, your idea of some fibreglass is a good/cheap one. What I have done is the fibreglass, but instead of the typical resin/hardener, use a two part flexible epoxy and put that over the glass fibre and squeeze it though with a plastic blade of some sort (doesn't have to be sharp). It won't look pretty from the inside, but does that matter? The epoxy is better at adhering to the plastic surface than typical fibreglass resin/hardener.

If you want to fix the crack on the outside surface, then you get a hand tool with a rotating head that has a ball shaped end.... run it along the crack and make a groove the length of the crack. Fill the groove with the two part epoxy. Then you need to sand it.... and paint it. I would still ad the fibreglass to the inside. Probably not worth it.

The other option is a plastic weld on the inside only..... but you need a plastic welder and to use a compatible plastic.

I'd keep it simple and just do the inside with flex epoxy (like something that fixes car bumpers) and fibreglass and just prevent the crack from growing.

**sibrit** · 16th July 2013, 14:39

Is plastic weld the same/similar to one of the hot glue guns?

If I pull the edges in tight, I guess it would not be very noticeable from the outside, so I can avoid the sanding. I just worry about matching paint colours 'cos my experience so far is that they always look different.

**Drew** · 16th July 2013, 14:48

I've been steered clear of plastic welding. It rarely is anywhere near strong enough for the vibrations on a bike.

Glass the back of it up, going past the crack's starting point by a bit. Bog and paint the front. Presto.

**Maha** · 16th July 2013, 15:57

Originally Posted by Drew

I've been steered clear of plastic welding. It rarely is anywhere near strong enough for the vibrations on a bike.

Glass the back of it up, going past the crack's starting point by a bit. Bog and paint the front. Presto.

Ducati and vibrations?...nahhhhhhhhhh

**Bassmatt** · 16th July 2013, 16:30

Originally Posted by Drew

I've been steered clear of plastic welding. It rarely is anywhere near strong enough for the vibrations on a bike.

Took my fairing into the local panelbeater to have it plastic welded, but he didn't want to do it. If I recall correctly (doubtful) he was worried that the heat was too much for that type of plastic(?). Something like that anyway.
He used some black gunky stuff on the inside which looks like it was painted on, it's held up well.

**Drew** · 16th July 2013, 16:44

Originally Posted by Bassmatt

Took my fairing into the local panelbeater to have it plastic welded, but he didn't want to do it. If I recall correctly (doubtful) he was worried that the heat was too much for that type of plastic(?). Something like that anyway.
He used some black gunky stuff on the inside which looks like it was painted on, it's held up well.

The composition of modern fairings has a high content of something or other, that doesn't take to the welding process.

I glass up the back of everything now, bonus is that if there are bits missing, you just fill the gap with fiber glass and bog it up.

**Metastable** · 16th July 2013, 17:01

Originally Posted by sibrit

Is plastic weld the same/similar to one of the hot glue guns?

If I pull the edges in tight, I guess it would not be very noticeable from the outside, so I can avoid the sanding. I just worry about matching paint colours 'cos my experience so far is that they always look different.

http://www.youtube.com/watch?v=D8rTwWRYb0c
This is a ghetto plastic welding technique.... they do make Plastic Welding Guns..... do a youtube search and you will find them. IT ISN'T a hot glue gun. Most hot glue guns won't stand up to the engine temperature. To use a plastic welding gun you need to melt the same type of plastic (usually ABS) as the fairing. If that is the case, then you do not have to worry about it melting, otherwise your fairing would have already been melted.

I hear you about matching paint colour.... it is a PIA.... often best to just paint everything again. Honestly, the easiest way is the fibreglass with a flexible epoxy on the inside. Just make sure you lightly sand and clean off the area the glass and epoxy will be placed (on inside, leave outside alone). Don't bother filling in the crack on the outside of the fairing, and it will probably look OK without having to worry about paint.

The plastic weld works too, but you need proper equipment and the correct type of plastic to melt.

FYI - when I bought my trackbike, every single piece of plastic had some type of damage.... it had been crashed on both sides. IMO, it is hard to beat the fibreglass/epoxy method. If you want to know what I did in detail, shoot me a PM.

Cheers!

**98tls** · 16th July 2013, 17:03

Never had any problems with plastic welding myself,seems strong enough.

**Drew** · 16th July 2013, 17:04

Originally Posted by Metastable

The plastic weld works too, but you need proper equipment and the correct type of plastic to melt.

Even with the right plastic, I'm sure I've been told it's a waste of time on bike fairings. Once it's melted, it becomes brittle for some reason.

Some geek will know all the guff about why. Bogan...Oh bogan. Where the fuck are you?

**Drew** · 16th July 2013, 17:05

Originally Posted by 98tls

Never had any problems with plastic welding myself,seems strong enough.

That is a surprise, considering how poorly the fairings on a TL line up with...everything.

P'raps I've been led up the garden path.

**98tls** · 16th July 2013, 17:12

Originally Posted by Drew

That is a surprise, considering how poorly the fairings on a TL line up with...everything.

P'raps I've been led up the garden path.

As i say never had a problem,ive had much larger welds than that one that have never come apart.

**Drew** · 16th July 2013, 17:13

Originally Posted by 98tls

As i say never had a problem,ive had much larger welds than that one that have never come apart.

Well there ya go....I appear to be standing in a garden.

**Metastable** · 16th July 2013, 17:13

Originally Posted by Drew

The composition of modern fairings has a high content of something or other, that doesn't take to the welding process.

I glass up the back of everything now, bonus is that if there are bits missing, you just fill the gap with fiber glass and bog it up.

What he said.... that is why I said you need to know the type of plastic you have.... and you need to match that with the melt if you do the welding.