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Making Fiberglass Fairings

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#1 Guest_Swiffer_*

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Posted 29 June 2004 - 04:26 PM

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

  1. What do you need?

  3. Evaluating the part to copy (the plug)

  5. Preparing the plug

  7. Making the mould

  9. Using the mould to make the new fairing part.

  11. Summary

  13. Things to know about polyester / comparison between polyester and epoxi

1. What do you need?

  1. 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.

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

  5. Polyester, the resin I use. May as well be 2 component epoxy (see.
       Discussion at the end).

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

  9. Hardener for the gelcoat and the Polyester

  11. 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.

  13. 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

  15. 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.

  17. 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)

  19. Plastic gloves I use dishwashing rubber ones or cheapo single use
       plastic gloves. You do need to use gloves ? see 12 below

  21. 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".Posted Image 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!

Posted Image 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.

Posted Image 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)

Posted Image 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.

Posted Image 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.

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

  3. 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 ...

  5. Do its neighbor until you have covered the entire plug.

  7. 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).

Posted Image 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.

Posted Image 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...

Posted Image 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

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

  3. 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.

  5. Precut glass fiber shapes.

Posted Image 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

Posted Image border='0' alt='user posted image' />

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


Posted Image 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.

Posted Image 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

Posted Image border='0' alt='user posted image' />

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

Posted Image 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.

Posted Image 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

  1. Clean, wax and apply release agent

  3. Precut fiberglass

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

  7. Reinforce vulnerable areas

  9. Trim with scissors before hardening

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

  13. Enjoy!



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!

#2 Macgyvfr



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Posted 29 June 2004 - 05:47 PM

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

You rock!!!

#3 KevCarver


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Posted 29 June 2004 - 10:47 PM

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

#4 Guest_kerplode_*

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Posted 29 June 2004 - 11:14 PM

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

#5 seadooloo


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Posted 29 June 2004 - 11:26 PM

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'!

#6 Guest_Swiffer_*

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Posted 30 June 2004 - 04:31 AM

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.

#7 dude


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Posted 30 June 2004 - 09:32 AM

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:


#8 Guest_Swiffer_*

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Posted 30 June 2004 - 09:50 AM

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

#9 dicoleman


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Posted 30 June 2004 - 12:33 PM

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:

#10 Guest_bigkev_*

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Posted 06 July 2004 - 02:48 AM

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.