56 AUGUST 2018 scca.com
INSIDE SCCA AUTOCROSS
ost SCCA autocross categories allow for
the removal of fender liners. Street and
Street Touring drivers often remove them
dynamically, so to speak, but then have to
reinstall them to remain legal. Some cars have
especially fragile fender liners and are prone
to spitting them out after a cone strike or two.
Some drivers are especially prone to cone
strikes. When those two groups intersect,
replacement fender liner budgets skyrocket.
Some fender liners are cheap, some not so
much. In many cases, though, those torn-out
fender liners may be salvageable. If you’re
anything like me, you have a few old, damaged
fender liners sitting around, and those
things make great raw material for repairs.
This seems like a good place for a quick
legality discussion. I’m pretty sure repairing a
fender liner isn’t in anyone’s factory service
manual, but I’m also fairly sure no protest
committee is going to take a protest on such
a repair seriously. These repairs are not going
to make anything any lighter, and a fender
liner isn’t on the list of usual aerodynamic hot
spots. Besides that, the end result of these
repairs should be almost indistinguishable
from a new undamaged liner. Oh, and by
the way, this is a perfectly normal approach
to a repair, and there’s a rule in the Solo
Rules that allows for this sort of thing.
There are two basic approaches to repairing
these thin plastic parts. Some plastics work
well with certain adhesives. When the damage
is too extensive for the glue approach, or if
your liners happen to be unfriendly to glues,
pop rivets may be a good option. Both glues
and pop rivets utilize a similar approach of
cutting a piece off the scrap liner to a shape
that covers both the damaged or missing
part of the liner being repaired. The key to a
successful repair is to overlap the repaired
piece by quite a bit – surface area is critical.
This applies to pop-rivet repairs too.
Having a really clean surface will make a
big difference on how well glues adhere, so
this is a good place to use some soap and
water, and maybe wipe the area with lacquer
thinner. Some glue prefers a rough surface,
so maybe some sandpaper use is in order.
Another consideration with both methods
is making sure the repaired liner will fit back
in place in the car. Most cars will tolerate a
double-thickness part, so the glue method
may be foolproof. Pop rivets stick out a
bit after they’re installed, so plan ahead
on where they are going to end up.
One really common type of damage is
a ripped-out mounting hole. Fortunately,
that is one of the easiest things to fix.
Fender liners with more serious damage,
however, will take more effort to repair, and
at some point it may make sense to buy a
new fender liner. Or if you are super frugal,
you could probably take a collection of half
a dozen mangled fender liners and go full
Frankenstein piecing something together.
The sad fact is that these repairs are not
going to make the fender liner all that much
tougher, so whacking a cone or two is just
going to rip it up again. On the other hand,
trial and error will teach you what approach
and which brand of glue works best on
your particular brand of fender liner.
Fixing fender liners isn’t glamorous, but for Street and Street Touring
autocrossers, it’s de rigueur | WORDS Paul Brown | MAIN IMAGE Perry Bennett
(BELOW) This fender
liner has plenty of surface
area for a glue repair.
(BOTOM) There are a
variety of glues that will
work to patch fender
liners. Devcon Plastic
Welder has a rather short
shelf life and is quite
smelly. JB Weld is a two-part glue that’s mixed,
applied to the parts,
and then the parts are
clamped together until the
glue cures. 3M 90 is an
industrial contact cement,
which means you apply
glue to both parts and
let it dry. It’s important
to note that these are
definitely not the only
glues available that claim
to work on plastics.