Tubbing a C5 Coupe
This document should be used as a General “Guideline” as there are
numerous things that can affect these instructions: 1)The type of C5 being
tubbed (ie. Coupe, Hardtop, Convertible), 2)The type of fiberglass being
used, 3)The type resin being used, 4)The type of tools
WARNING: Anyone attempting to tub their Corvette by
following these instructions does so at their own risk. If you don’t feel
comfortable performing this task yourself then please hire a
– 3″ Cutoff wheel Air-Tool or a Dremel Tool with cutoff
wheel or both
– 6″ sanding wheel Air-Tool, or a sanding block
– Flat-Head screwdriver
– Torx 47 (aka. T47)
– Pop rivet gun (1/4� bit preferred)
60 grit sand paper (for your sander)
– Cutoff wheels (for your cutting
– Resin (Polyester or Epoxy)
– Fiberglass mat
– 2 oz.
Bottle of Gorilla Glue
– Pop rivets (1/4� steel rivets preferred)
Disposable mixing tray (like for painting)
– Disposable gloves
Disposable painters� jumpsuit (jeans and a long sleeve shirt will do)
Full protection goggles
– Respirator (one that seals REALLY well)
15 ft. of plastic covering (like the kind used by painters)
– Black marker (sharpie)
– A hand full of plastic sandwich
– Grey spray paint (glossy, not primer)
– Black spray
paint (flat black)
Step 1. Loosen lug nuts on the rear
Step 2. Raise rear of car and support with
Step 3. Remove rear wheels.
Step 4. Remove
rear wheel well liners and place screws in a plastic baggie marked �WHEEL
WELL LINERS�. This isn�t necessary but it is helpful when it comes time to
put everything back together.
Step 5. Remove all interior trim from
the rear compartment area��.This will differ slightly between Coupe, FRC,
and Vert. Put all screws and retainers pertaining to each trim piece into
it�s own plastic baggie marked accordingly.
Step 6. Remove all
carpet and padding from the rear compartment area�.This will differ
slightly between Coupe, FRC and Vert.
Step 7. Ensure both rear
wheel wells are fully exposed in the rear compartment and underneath with
nothing attached or near either of them.
Using a black marker, and picture 1 as a guide (taking note of the areas
circled in green), draw the �proposed� pattern on the fender wells. The
main thing here is to ensure that the �proposed� pattern doesn�t interfere
with anything like the speaker mounting holes, support brackets,
body/frame, etc. If there are then make the necessary adjustment to the
pattern. Once this �proposed� pattern is checked and verified for
clearance then you�re ready to make the cut.
NOTE: The �proposed�
pattern should follow the edge of the wheel well from back to front near
the top of the wheel well just after it transitions from horizontal
towards vertical (basically the start of the curved edge on top). On the
bottom be sure to go out about an 2� away from the wheel well, avoiding
all obstacles as shown in picture 1, however DO INCLUDE the two top wheel
well liner mounting braces (there are two braces per wheel well) within
the �proposed� pattern. Also take note of the Targa Top Mounting Bracket
location shown in picture 2, you can cut this off or do like I did and
just cut the fiberglass off it.
Using the plastic drop cloth, cover and seal the interior of the car from
the rear compartment area. If you do not get a good seal then fiberglass
dust from cutting will get inside the interior of the car and will make
Step 10. Using a cutoff tool or Dremel tool with
cutoff wheel, cut out the rear wheel wells following the pattern
Step 11. Dry fit the newly cut wheel well panel back into
the wheel well to get an idea of where to mount it. Then mark rear
compartment floorboard around the two wheel well liner mounting braces.
Then cut out the two notches to allow clearance for the wheel well
Step 12. Using a sander, sand the edges of the
new cuts (within the rear compartment) to smooth them out. Then sand the
area about 2�-3� away from the cuts and all points in between. This will
allow the resin to stick better since the gelcoat is sanded off. If you
are planning on glassing the underside of the wheel well then repeat Step
10 as necessary for that area.
Step 13. Using a sander or
hand-held sander, sand the edges of the piece that was just cut out. Then
sand 2�-3� away and all points in between on the top side. If you are
planning on glassing the underside of the wheel well then repeat Step 11
as necessary for that area.
Step 14. Once both items are prepped,
then clean the areas thoroughly with water or shop-vac or by hand. The
main thing here is to make sure the area that the new fiberglass will be
mated to is clean and free from contaminates.
Step 15. Dry fit the
new wheels, snug down the lug nuts, and then lower car. This will give you
an idea of how much space is ACTUALLY needed for the new wheels. Then
place the panel, that was cut out of the wheel well, back into the wheel
well to get an idea of where to mount the panel.
should be at least �� of space between the new wheels and the wheel well
panel. Also make sure the panel is straight and positioned in such a way
that will allow the contour of the wheel well to be maintained (as much as
possible at least). Once the desired location is determined mark the area
on the rear compartment floorboard (draw a pattern around the panel base)
for future reference.
Step 16. With the wheel well panel still in
place, drill three holes through the panel base and through the rear
compartment floorboard. Pop rivets will eventually go into these holes to
hold the panel in place. So don�t rivet the panel in place just
Step 17. Using a wet paper towel, wet the underside of the
wheel well panel base and the area of the floorboard in which it will be
mounted to (the pattern area drawn in Step 15).
Immediately after Step 17, apply a liberal amount of Gorilla Glue to both
mating surfaces (panel & floorboard), and then set panel in place (as
outlined by pattern) aligning pop rivet holes.
19. Once panel is in place install the three pop rivets. This will aid in
applying pressure to the area that is being glued. See picture
Step 20. Let glue COMPLETELY dry (about 24hrs).
In the meantime, precut all fiberglass into 3�x7� strips (you may want to
make a few that are bigger and a few that are smaller for finishing). Do
this prior to mixing the resin. This will aid in reducing the time needed
during glassing since resin will start to harden after about 20 minutes.
Plus it�s easier to just grab a precut strip then it is to try an cut one
with sticky fingers.
Step 22. Once the glue has completely dried
take a piece of cardboard and cut out a strip about 3� wide and about 8�
long and wrap it in sirran wrap. Take that piece of cardboard and roll it
up lengthwise. Now take some duct tape and tape that piece of sirran
wrapped covered cardboard to the underside of the wheel well covering up
the �gap�. Repeat this for the entire �gap� on both sides of the car. This
will act as a support and a mold for the fiberglass. See pictures 7 and
Step 23. Once the fiberglass has been precut, then you�re
ready for mixing resin. I used Epoxy Resin because it�s a 1:1 mixture
ratio, however Polyester Resin is just as good but requires a little bit
more complex mixing ratio (the container should give proper mixing
instructions). So it�s up to you as to which type you want to use. In
either case NOW is the time to mix it. Be sure only to mix enough resin
that you can actually use within a 15-20 minute time
24. Now that the resin is mixed, take a strip of precut fiberglass and
soak it the resin. You�ll see the fiberglass strip change from �white� to
�translucent� as the resin is absorbed by the fiberglass.
Take the soaked strip of fiberglass and very lightly squeegee off any
Step 26. Lay the soaked fiberglass strip across the
�gap� overlapping the wheel well and the wheel well panel by about 2�+ on
Step 27. Repeat Step 24-26 overlapping the previously
laid fiberglass by an 1� or so until the entire �gap� has been covered on
both wheel wells. If some smaller or bigger pieces of fiberglass are
needed then add them as necessary. Mix additional resin as
Step 28. Let first layer of fiberglass set (about 6 hrs
give or take a few).
Step 29. With a hand-held sander lightly
rough up the first layer of fiberglass. This will help the second layer of
fiberglass adhere better to the first layer.
Step 30. Repeat Step
24-28 to add a second layer.
Step 31. I only applied two layers of
fiberglass, however if you want to lay three or more then repeat Step 30.
Also as a tip, if you lightly sand the last layer and mix up a small
amount of resin, then spread the resin across the fiberglass with your
hand smoothing it out as you go, it will dry almost as smooth as
glass��makes the finished product look really good.
Step 32. If
fiberglassing the underside of the wheel wells (I didn�t) now is the time
to do it. Sand the area and then repeat Step 24-28.
Step 33. Once
all fiberglassing is done then CONGRATULTIONS, the hardest parts are over
with. Now take the can of gray spray paint and paint the rear interior
wheel wells gray. See picture 9.
Step 34. Paint the underside of
the wheel wells black.
Step 35. Allow paint to dry.
Reinstall all carpeting and padding. Carpet & pad trimming will vary
depending on how much you tubbed. Typically removal of all padding from
the sides of the wheel well will be required. Also slight carpet trimming
around the speaker opening (Coupe, not sure on FRC or Vert). Also due to
the location of the rear speakers on Coupes (again not sure on FRC or
Vert) you may have to screw the very back edge of the speaker trim housing
to the newly extended wheel well to get it to lay flush. Do this on the
inside of the mesh speaker cover as this will help hide the
Step 37. Reinstall all trim pieces.
Step 38. I
didn�t modify nor am I using the wheel well liners. If you want to use
them follow the instructions in the �C5 Tech Tips� section on
www.corevetteforum.com regarding tubbing a C5 (obviously the other set of
C5 Tubbing Instructions listed).