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Guest Swiffer

Making Fiberglass Fairings

35 posts in this topic

Making your own fairing parts


To make GRP (glass fiber reinforced plastic) copies of most fairing parts is

 quite possible for a reasonably handy person. Does your friend have an undertray

 or a hugger that you like...?

For me it started when the road turned left (but I didn?t). The cost of replacing

 the fairing parts was not small, to put it mildly. This was before Internet

 (for me), so I let Mr. Honda grab all of what was in my wallet, and then some.

 I couldn?t have any more of that, so there was only one thing to do to make

 my own plastic parts in the future.

I chose to do this "how to" on the simplest shape on the bike - the

 seat cowl. The pics are small and distorted to fit the pages and limit file

 size and should be considered as illustrations.

Good luck! /Swiffer a.k.a. U-Joppe

Overview of the contents



What do you need?


Evaluating the part to copy (the plug)


Preparing the plug


Making the mould


Using the mould to make the new fairing part.




Things to know about polyester / comparison between polyester and epoxi

1. What do you need?



Wax and maybe rubbing to make the original shiny. I use rubbing,

   since the surface was a little coarse. If your surface is really clean and

   nice, wax will do.


Releasing agent Typically polyvinyl alcohol, get it in a boat supply



Polyester, the resin I use. May as well be 2 component epoxy (see.

   Discussion at the end).


Gelcoat for the outer layer in moulds and, if you choose, the fairing



Hardener for the gelcoat and the Polyester


Glass fiber Non-woven (chopped strand) mats are good enough for a

   mould. When I make the fairing part I may use woven mats that, weight for

   weight, are stronger.


Jars to mix polyester and hardener. Glass jars are good but, when

   I do a lot of jobs, I run out or just dislike to thow away so many (can?t

   recycle with plastic in them...), then I use old plastic jars. However, all

   plastic cups won?t do, those made of polystyrene will slowly "melt"

   (but may still work if you work fast enough). The hardening process is exothermic

   (produces some heat) so, if you mix way to much, make sure that the remaining

   unhardened plastic is placed safe and in something that will tolerate the



Brushes/Paint rollers To apply polyester and release agent and also

   to work the polyester into the fiber mats. I wash them in acetone so I only

   need one of each.


Mask that filters organic vapors Not just a dust mask. Polyester/styrene

   vapors are not good for you (You can trust me on this one ? I?m a toxicologist)


Plastic gloves I use dishwashing rubber ones or cheapo single use

   plastic gloves. You do need to use gloves ? see 12 below


Protective clothing You need to wear clothes that, at least, cover

   your forearms (I wear a high collar sweater ? for all jobs, however small).

   Just holding unfinished glass fiber projects (or carbon fiber for that matter)

   will make your arms itch for days!! When sanding, sawing or filing you can?t

   do without. I can tell you plenty of stories when I have ignored this and

   regretted it for days...


2. Evaluating the part to copy

I?ll start off with stating the obvious. Make sure that the shape you are trying

 to copy has a "natural release".Image15.jpg border='0' alt='user posted image' />




Pic 1.

Unfortunately it?s seldom this easy to see. However, as long as you choose

 to copy an existing part chances are that it will be all right. Honda needed

 it to come off their moulds too!

3. Preparation of the part to copy

If you already have broken the part you need, glue it back together with superglue

 and sand it a bit. It may not work as fairing but will make the perfect "plug".

 If you intend to use the part you are copying again, you need to be a little

 careful! Polyester can be tough on decals. Cover those with some type of film,

 you can fix the marks the film leaves later. I have never covered my decals

 and never had a problem with it, but don?t say I didn?t warn you.

First, you need a nice shiny surface on the part you want

 to copy. Not only so the copy will be nice, but so that the mould you are about

 to make will let go. If the part is not shiny and smooth, rub away with some

 polishing compound and finish it with 2 waxings. If you don?t do this thoroughly

 you will be sorry later!

Image1.jpg border='0' alt='user posted image' />

Pic 2. Glue bits on and make the surface of the original shiny so the mould

 lets go.

Second, apply release agent (see pic 9). I actually don?t know

 what I use! I bought a can from a boat builder and I cannot remember what he

 said it was. Probably polyvinyl alcohol, at least this is widely used

 for this purpose. Some uses only wax, but I don?t quite trust it.

4. Making the mould


"Paint" the original with two or three layers of Gelcoat. Let the

 Gelcoat almost harden between the layers. If you don?t let it harden a bit before

 the glass fiber application (below) the fibers may push thru and ruin the nice

 surface the gelcoat is supposed to give. Not letting it harden fully will reduce

 the risk of the layers separating. If you can?t be there until later, wash the

 gelcoat with acetone, or something similarly that takes everything fatty away,

 before you apply the next layer. A few % (5 or so) of paraffin in the Gelcoat

 will give it an even glossier surface/makes it release from the plug easier,

 but I don?t find this necessary.

Image2.jpg border='0' alt='user posted image' />

Pic 3. The original, "painted" with a few coats of Gelcoat

Polyester and glass fiber

A. Prepare the glass fiber

Precut the shapes you need in the quantity you need so you don?t have to do

 that in the middle of the applying process ? it can get unbelievably messy!

Non-woven mats of glass fiber will follow most shapes (with the exception of

 really sharp edges), but you will get excess of material in the wrong places

 when you try to fold it in unnatural ways (see Pic 12). I rather use a few different

 pieces that together builds the shape of the mould.

The Gelcoat gives a nice surface but is a little brittle and will crack if

 you don?t support it with something. That?s why it?s now time for GRP (Glass

 fiber Reinforced Plastic). The plastic in my case is polyester but you may as

 well use epoxy. (See my comparisons between working with polyester and epoxi

 at the end of this stunning and whitty write up)

Image3.jpg border='0' alt='user posted image' />

Pic 4. Precut enough glass fiber "sheets"! It may be hard to get

 one piece of glass fiber mat to follow the entire shape. Make "sub parts"-

 here?s the top of the seat cowl.

Image4.jpg border='0' alt='user posted image' />


Pic 5. And this one is the front. The solid line is the actual shape, the dotted

 line is were I cut, giving some overlap.

B. Laminate!

The best thing now is if you have an hour or so on your hands so that you can

 do this in one sequence. Three layers of fiber will do for the big surfaces

 of most bike related projects. Reinforce with extra layers in areas that may

 be strained.


Apply one thick layer of polyester onto the gelcoat and ...


Place one of the precut pieces of glass fiber mat onto that. Use

   a brush or (preferrably) a paint roller to work the mat into the polyester.

   The glass fiber should to look wet (not white) all over! Apply more polyester

   if it doesn?t. You can be liberal with the polyester now, you are making a

   mould, not a piece of fairing, so weight is not an issue. When one precut

   shape is applied ...


Do its neighbor until you have covered the entire plug.


When you have done that, go on with the next layer of glass fiber in the

   same way. You do have time to admire your work, but do the next layer before

   the first layer have fully hardened. In this way you don?t run the risk

   of layers separating later (this is especially important when you make the

   fairing part of course).

Image5.jpg border='0' alt='user posted image' />

Pic 6. A glass fiber mat will soften when polyester is applied. Non-woven mats

 will easily follow round shapes (pretty much like a fancy hairdo in the rain).

 Work "wet in wet" ? i.e. apply the next layer while the one before

 has not yet hardened.



C. Trim

When the applying process is finished, let the resin harden for a while. But

 before it has hardened fully, cut the excess glass fiber with a pair of scissors.

 This will leave you with less sawing and sanding and you will love that! Now,

 leave it until tomorrow to let it harden and then... file and sand the laminate

 to the edges of the plug.

Image6.jpg border='0' alt='user posted image' />

Pic 7. Use regular scissors to trim most of the excess off while not quite

 hardened. You can do it later but then you will need a saw... and this saw dust

 itches like crazy!

All that remains now is to get the mould to let go of the original.

Twist and bend until you see it separate somewhere, then start working in that

 area. I use my air compressor to blow air into the crack, this usually separates

 them. It can be a bitch though...

Image7.jpg border='0' alt='user posted image' />

Pic 8. Phew! It worked! The original is gone, and mould is loose. Just need

 some fine trimming. The brownish stuff in the mould is the releasing agent,

 it tears or washes off.

If you find some imperfections you can wet sand the surface with a 1200 grit


But if you did everything right, the surface is great and all you have to do

 now is to...

start over again!!

4. Using the mould to make a new fairing part


 This process is basically the same as making the mould. There are some things

 that can be considered though.

Do you want it light, strong or good looking? It?s easy to use

 too much resin. The rule of thumb for max strength/weight ratio is equal weights

 of fiber and resin. Use the paint roller to even out the resin and work it into

 the fibers, this saves much weight. I don?t use a gelcoat surface on my light

 fairings since gelcoat cracks to easily and weighs too much for this use. It

 does give a very good surface for parts made to look good.

Reinforce areas that you think will be strained. Corners, edges

 and holes for fastenings are typical such areas.

Make a quick and dirty first try. Things may turn out differently

 than expected so don?t use too much energy on that first copy.


Things to do before you can start applying polyester and glass fiber



As with the original, you have to wax and cover the mould with a releasing



If there are some parts with sharp edges (and there always are) make some

   plastic bag covered sponges (see pic 14). You will see how they work later

   but make them now.


Precut glass fiber shapes.

Image8.jpg border='0' alt='user posted image' />

Pic 9. Wax and then cover the mould with releasing agent



Apply polyester and glass fiber

First apply a coat of polyester onto the mould. Now, this is IMPORTANT: if

 you want a nice smooth surface with no small pits in it, without using gelcoat,

 let the first coat of polyester gel before applying a thin second coat and then

 apply the first glass fiber layer onto that.

As you see on the following pictures I don?t use different precut glass fiber

 shapes as I did with the mould. On this kind of simple shape you may go either

 way but the precut is safest for best surface result. The excess glass fiber

 will fold and I cut it so that it won?t form pleats and the excess can go on

 top of each other more easily

Image9.jpg border='0' alt='user posted image' />

Pic 10. When applying glass fiber and it makes folds like this...


Image10.jpg border='0' alt='user posted image' />

Pic 11. ... I just cut it so it makes layers instead, without creases.

Add more polyester to the piece and work it in with a brush or a paint roller

 (not upsetting the strands to much) until all the glass fiber is "wet".

 Try not to add more polyester than you need to get the glass fiber all

 wet, it is easier to add than to take away resin. Time for the next layer, work

 wet in wet as with the mould. 3 to 4 layers will do for most parts, most of

 my seat cowl is only 2 layers since it isn?t really doing anything but trying

 to look good. Where I anticipate strain (mounting tabs) it is 4 or 5 layers.

As you see in the next pic, there are ways to make glass fiber follow even

 sharp bends.

Image11.jpg border='0' alt='user posted image' />

Pic 12. Where it is hard to get the glass fiber to follow the shape of the

 mold, this method of using something spongy in a plastc bag may work.

Trim the edges as you did when making the mould and when it has hardened fully

 ? next day or so if you use polyester ? bend your new fairing part from the


Image12.jpg border='0' alt='user posted image' />

Pic 13. With some persuation it came off. Looking good so far...

Image13.jpg border='0' alt='user posted image' />

Pic 14, ...But THIS is

 the moment of truth ? ahhh carma!

Now all that remains is some fine edge sanding and then the hated paint job.

Image14.jpg border='0' alt='user posted image' />

Pic 18, It is easy to get carried away when it is little more than an hours

 job to make a new one! (the strange patterns are didgital, not there in real



Summary of the steps



Clean, wax and apply release agent


Precut fiberglass


Apply (gelcoat x2, let gel before...) polyester and glassfiber, repeat polyester

   and glassfiber while wet


Reinforce vulnerable areas


Trim with scissors before hardening


Trim with file/paper to the edge of the plug/mould





Things to know when you?re working with Polyester



The DIY "polyester" you buy in a can is not just polyester. It

   also contains the solvent styrene and, if it?s blueish when not hardened,

   some organic cobalt compound (accelerator) and sometimes some wax.


The styrene is a very good reason to wear a gas filtering mask.


The wax is there so that the styrene will not evaporate too quickly (making

   it dry before it hardens). Some wax will be on the surface after the hardening.

   You need to take this away if you add an additional polyester layer after

   the previous layer has hardened, otherwise there is a risk that these layers

   will separate in the future.


Too much hardener in the polyester will "burn" the plastic leaving

   brown weak spots.


Too little hardener slows down the hardening process (surprise!), sometimes

   so much that the styrene has time to evaporate and the polyester dries before

   it has the time to harden.


Before it becomes solid it gels for a short while. This gel cannot be worked

   and it?s a good idea not to try to reshape it when you start seeing that.

   To add the next layer is OK though.


Comparison between polyester and epoxi

I mostly use polyester when working with glass fiber. Still, many things speaks

 in the advantage of epoxi.



The smell! Epoxi (most anyway) does not contain a solvent and smells less.

   It also is less toxic (allthough allergenic so keep dressed and wear a dust



Epoxi is stronger.


Epoxi gives a more scratch resistant surface (won?t help the paint you paint

   it with I guess).


Epoxi is resistant to many chemicals (including gasoline and water)


Epoxi goes through a "chewing gum" state where it is possible

   to shape. This is great for places were it is hard to get the laminate to

   follow the mold or plug when the laminate is wet.


Epoxi is clear, so if you want to imbed a decal or see that cool looking

   carbon fiber, epoxi is your choice.


If you keep the jar of mixed epoxi in the freezer, the so called "pot

   life" will be in the order of weeks! (depending on the Epoxi used obviously,

   there are several types with varying caracteristics) This way you can minimize

   the number of batches you have to make.





Epoxi is more expensive.


The weight relationship between base and hardener is important. Small deviations

   gives big decreases in quality. This is a pain when working with small batches.


The mixing of base and hardener is very important, polyester is more forgiving

   in this sence.


That?s all folks, and good luck!

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:bow:  OUTSTANDING!!! I've always wanted to do this! Now...can you tell us how to do the same with CF???  :D

You rock!!!

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Should be the same, right?  Just sub CF for GRP?



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Wow!  I declare this the coolest how-to post EVER!  :bow:

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Allright, that is the best post 'how to'  I've seen. I always wanted to know how that is done. After your done with the fiberglass seat cowls, can you make us some really cool looking carbon fiber huggers? Like someone else said 'You Rock'!

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The only difference in working with Carbon Fiber (that I have noticed) is the price, availability and (as I think I said in there somewhere) that you should use epoxi. Using polyester should work (I haven't tried) but then it will not look as good. The reduction in weight for the same strength is not big (compared to glass), and you need to be cautious not to apply more epoxi than you need (that will take away any gain in weight you may have done...). For a non-racing VFR it's all bling... (did I tell you about my CF seat cowl and NACA ducts? :P )

And CF huggers - borrow a hugger, follow the steps and you have one next week!

But, learn the steps with glass fiber first - saves money and anguish.

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Very cool swiffer.The scarey part for me would be covering my cowling with that releasing agent, for fear it would f*** it up. How bout making us some 5th gen huggers :D

I totally trust you  :bow:


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The releasing agent will do nothing to harm your cowl. What possibly could be a minor risk is if you don't have enough of it on the part your copying when applying gelcoat.

I'd make a hugger for a friend if he/she supplied me with something to copy and lived close by so he (or she) could come and yell at me if it broke... :pissed: So next time you're in the neighbourhood... :D

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Awesome post! :cool:   The possibilities are unlimited.  I've done fiberglass repair work on cars before... but never anything this extensive! :goof:

Very, very, cool! :cool:

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Good thread......

I make CF and fiberglass fairings on the side for Ducati's, R1's GSXR's etc, and am a qualified "glasser", a couple of points to note. Be sure that you remove all your decal prior to starting.  Be sure when using CF that you lay it up at a 45 degree angle as it draps better, and looks better. To get that great deep look try using a top coat of surf board finishing resin, Looks great.

Happy to answer any FYI's you guys have. Trying to find the time to get 2003 moulds finished so should be able to offer good price on parts soon.

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1. Be sure that you remove all your decal prior to starting. ?

2. To get that great deep look try using a top coat of surf board finishing resin, Looks great.

1. Or cover them as I point out in "how to"

2. What is that? Living in a non surfing area I've never heard of it. A brand name?


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Cool.  Anybody have a right side mid fairing from a '95 I can borrow?  I'll trade you a carbon/kevlar left side peg bracket.

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Hmmm... a lot of replies have gone missing - shame, there were some good pointers in there.

Get some polyurethane based foam sheats used for isolation. These don't dissolve if you get it in contact with polyester, as other isolation foams do. Even so, after you have shaped the "plug" spray it with some paint -that will improve the finish. Non urethane fomes can be used also, but you need to cover it with gladpak or some other plastic film before use. I

f you want to go really cheap you could go to a building site and ask if you could have some ground isolation foam sheats that has broken. They throw lots away anyway.

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I wonder how you would be able to form the foam insulation so nicely for the plug - point in case - seat cowl.

Any pointers on working with foam insulation to use as a plug would be great and think that it would be cheaper and easier too.

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The polyurethane foam I have tried (I don't have a too much experience in this) can be carved, sawed and sanded to shape. However, you have to make the "negative" of the finished product otherwise you will apply the laminate on the side that will end up as the outside. It is harder (but not impossible) to get a good finish that way. Or, you can do it in two steps - first make a foam plug with the right shape and then make a mould of that, as I described above. It enables you to alter the original shape but makes it harder to find the place for fasteners, imo.

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Hey swiffer, when you sending me my 5th gen hugger? JK great write up again. I know its been up awhile but keep checking back to see if you have made any huggers yet  :goof:


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As soon as you send me a 5th VFR to take meassures from!  :D

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Swiffer, could you be convinced to make me some CF naca ducts for my 97?   :D

And while I'm thinking about it.. a CF bellypan would look pretty sharp too....  :idea: wink.gif

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Swiffer, could you be convinced to make me some CF naca ducts for my 97? ? :D

And while I'm thinking about it.. a CF bellypan would look pretty sharp too.... ?:idea: wink.gif

Naca ducts - not if you are in a hurry. Before the summer - propably.

Bellypan -  maybe I should get around to do something about that some time...


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As soon as you send me a 5th VFR to take meassures from!  :D

I'll get right on that swiffer. I'm still holding out hope for santa's visit too :D

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Is there any chance of getting the images that go with this GREAT how-to?

Thanks. Greg :D

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I'll see if I still have them on my computer

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I could send you Murphy's X-One integrated chain guard/hugger next winter but I can't believe there's no one near you with a 5th gen. VFR

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I could send you Murphy's X-One integrated chain guard/hugger next winter but I can't believe there's no one near you with a 5th gen. VFR

I've got a 5th gen hugger mold already made. Also have a reshaped 5th gen mold pretty much the same shape as the one Francine has.

Haven't produced any copies yet though.

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