How to make a fiberglass seat pan
Additional Information
We get numerous phone calls about seat pans, so we decided
to do this tutorial to show you how we make a seat pan.
There are many different ways to do this and there are many
shortcuts however, we feel that this is the best and safest way
so as to not damage your bike or paint. Make sure you do this
in a well ventilated area, in the shade and take your time.
Before you start, there are a couple of things to you need to figure out.
The first, is the shape you want your seat pan to be and how it will sit in
the front at the tank and in the rear on the fender. We trim the backrest
area about seven inches or so up the fender. When you add about two
inches of foam to the bottom, you will need to have enough seat pan left
for some back support. The shape of the back depends on what you like
but most of the time we shape the seat pan to match the rear fender.
We try not to get too crazy with the shape on the fender. Something
smooth or to a point is ok but when you start doing things like flames or
similar, the seat doesn’t usually come out great. Think about it.
The second thing to figure out is how you are going to mount the seat
on the bike. Since almost every bike is different, the way to mount the
seat will be different and this needs to be figured out at the start. The seat
in the tutorial fits into the stretched tank area in the front and will have
a suction cup on the rear. If you send us a seat pan and want us to
install a suction cup you will need to mark where you want the suction cup to
go. Make sure that the area on the fender where the suction cup
touches is smooth so the suction cup can suck. No holes or dents,
curved is ok. Also the suction cup needs to be 1 1/4 inch from the edge of the
seat so it can be accessed in order to relieve the pressure when the seat needs
to be removed so keep that in mind when marking where you want the suction
cup. Some bikes can get a tongue on the front that can
hook into something or maybe a couple of bolts glassed into the pan
somewhere. Some seats have just Velcro holding them to the bike.
I am not a big fan of using Velco to hold a seat on because your seat could
easily fly off should you happen to stand up or lift off the seat while riding.
What ever you decide, now is the time.
Start with blue tape to protect the bikes paint. Overlap the edge of the tape as you put it on.
Use cardboard to cover holes and to
make the bottom of the seat pan flat.
Tape as much as possible to protect the paint.
Take the A/C aluminum tape and put it on top of the blue tape overlapping the edge of each piece.
Put the aluminum tape over the blue tape carefully covering it completely.
NOTE ARROW: We have now covered the fender mounting bolts with cardboard to flatten the area.
Now take the plastic and entirely cover the bike.
Be safe not sorry
Wrap the bike as much as possible to protect from resin splatter.
Put on the gloves and start waxing. You need a few coats of wax. You know "Wax on Wax off". Wax every nook and cranny. It will help to make removing the seat pan after its fiberglassed easier.
After the wax is applied it is time to start fiberglassing. Get your fiberglass mat ready before you begin. It will be easier and your pan will be stronger if you use small pieces about 5″ square. Pull small pieces off the larger piece by hand so the edges are shredded.
With gloves, mask and eye wear on mix your resin according to directions and the weather and please do this in the shade. Use your brush to spread on a coat
of resin.
Take your first layer of fiberglass mat and start putting it down with your brush. Use only enough resin to soak the fiberglass. Use the brush to push excess resin and air bubbles out towards sides. More resin does not make the pan stronger.
Try to get it in every nook and cranny as possible. You need at least 3 to 4 layers of mat overlapping each other. Pay attention to not have any thin areas. You can always add a piece if you are short or if you think it is to thin. Thick is ok.
We like to use a layer of roving or cloth for extra strength if you have it. Combining different fiberglass materials adds strength to the pan.
If you're satisfied then you are finished. Clean up everything and let the fiberglass dry overnight.
This part can be kind of hard. Use thick gloves and grab an end and pull up carefully. Finding a place to pull up can be tricky but once the pan lets loose from the bike it will lift right off.
After the fiberglass is off you can remove the plastic and tape from the bike and put on new tape to prevent you from scratching the paint as you fit and trim the seat pan. Find and mark the center at the front and rear.
Start with a center mark when trimming the pan. You can use an air saw or a band saw or even a cut-off wheel. Trim and reinstall several times so you get just the shape you want.
Check the fit and try to get the pan as symmetrical as possible. When you are happy with the shape, sand all edges as smooth and straight as possible. You want the out side edge of the pan to be straight when you are looking down at it as well as looking at it from the side. You want the bottom outside edge to be as smooth as possible.
There you go, you are done. Now all you have to do is send it to us for the coolest seat you have every owned.