Tubbing a 2000 FRC C5 Corvette

The Corvette Forum has brought me
hours of enjoyment and great information for my 2000 FRC. It is only right
that I put some time back into the forum. Below is a description and some
photos on how I did the tubbing on my car.
After looking at the
availability of tires at the time of building my project car I decided
that the Michelin Pilot Sport 335 30 18 on 12 inch wide HRE 547s would be
my choice. I used the Mallet offset of 68mm (9 1/8 inch backspacing). The
only problem with
this selection was that I would have to modify my
inside fender wells to get them to fit.
Get ready for some
comments when your friends see you cutting up a brand new car. Just smile
and get to work.
Take out the inside carpet to provide this view of
the fenders.

It is helpful to
remove the seats and cover the interior because there will be a lot of
fiberglass dust etc.

Remove the inside fender skirts inside the wheel
wells, then inside the trunk draw out the cutout line as shown in the
photos. I decided on a 2″ tub. As you can see, I left the support tower
intact. Cut the fender with a dremel tool and diamond cutoff wheel. You
can use masking tape and draw on it for your lines (easier to make
corrections or if you are brave, just draw on the glass.


Sand the resulting
edges with 60 grit. Note the hole cut out on the flange of the part to
accommodate the bulge in the trunk floor from the shock tower
relief.

You will have to cut the
forward edge of the part as shown to allow clearance/fitment for the frame
of the car. When you move the fender in, angles go out of plane. You can
use my photos to help you shape the new part.



Now cleeko (sheet metal screw) the part to the floor so
it will line up when you glue it in place. We used industrial strength
gorilla snot or you can get a tube of what GM uses to bond the vette
together to do the job. Note the 60 grit sanding completed along the edges
so the resin will bond. By the way we used vinlyester
resin for the
fender wells and epoxy resin for the fender skirts. Put some pop rivets in
your cleeko holes to hold it in place as it dries.

And
the bonded part ready for glass. Note the wax paper covered cardboard
lining the inside fender acting as a mold for the fiberglass. If you use
epoxy instead of vinlyester resin, cover the mold with Siran Wrap
instead.

We filled the gap
with glass until it was flush and let it dry. Then came back and laid two
more layers with about a 2 inch overlap to finish the job. It was plenty
strong and we did not glass the inside of the fender well to help with the
clearance of the fender skirt/liner.


And
the finished inside left fender.


Now take the
fender skirt…

and cut it out along
the lines shown in the photos below. You will have to cut off some of the
inside half around the frame area so that the geometry will work. Once
they are cut, remove the bracket from outside the rear storage area and
move it in two inches. For the two brackets on either side of the shock
tower, I just drilled through the original bracket holes in the cutout
part and it fit perfectly.
Remount the two halves back in the car
after preparing them for glassing.
Here the skirt is shown with the
inside laminates competed. I bolted them in before glassing the inside of
them so I could build up a mold around the frame area and make sure of
fitment. I kept the factory spacing between the skirt and the body the
best I could.

Note the cabosol and mill
fibererd epoxy resin we used to fill in any gaps along the edges before we
put the top layers of glass on. By sanding the edges down, the glass will
stick better. The material GM uses for these liners is tough to bond to
and that is why we glassed both the top and bottom of the parts. Be sure
to sand it real rough before glassing.

As far as the carpet
goes, just cut out the molded carpet fender area at the right angle bend
of the fender and glue it on the fender… foam and all. Then cover the
whole inside fender with carpet glued to the old piece.
Here is a
shot of the completed right inside. Trim the tower support trim piece so
that it fits well on the carpet. It is really hard to tell the car has
been tubed at all and I am extreemly happy with the results. The 335s look
awesome on the car!


Here are
some shots without engine in car.