Pinewood Derby Stories and Photos from Maximum Velocity
Weigh-in Problems and How to Avoid Them
By Randy Davis
(An update of an article originally published February 23, 2005)
I have been the head race official for many pinewood derby races. One
of the tasks is to manage the check-in process (which really means
"do everything you can't find someone else to do!"). As I have helped
kids and parents check-in I repeatedly see the same major mistakes. It
doesn't seem to matter whether we have workshops, pass out detailed
instructions, or pass out simple instructions; the same mistakes
appear each year.
In today's article, I will identify the main issues that arise at
weigh-ins, and suggest some ways to remedy these problems. My intent
is to provide race officials with some ideas as to how to deal with
these issues, and to help pinewood derby "freshmen" to ensure these
problems don't occur with their car.
NOTE TO RACE OFFICIALS
If at all possible coach the car owners to make their own adjustments
(after all, it's their car). If at all possible, don't put yourself in
the position of working on the car yourself, as damage can easily
occur. When it is apparent that you will need to work on the car, ask
the car owner if they will permit you to work on the car. Then tell
the owner that you will do your best, but that the car may be damaged.
CAR IS SIGNIFICANTLY UNDER WEIGHT
This is the most common problem that occurs. Oftentimes, new car
builders do not understand that weight must be added to the car in
order to make the target weight.
The only reasonable way (i.e., without risk of damage to the car) to
add 2 or 3 ounces of weight to a car after it is painted and assembled
is to attach a zinc plate weight under the car (available from most
hobby shops). If this type of weight is used, make sure that the
bottom clearance specification is met.(1)
Officials - These plates typically sell for about $3.95.(2) So
consider purchasing a few and then selling them to the folks that
bring in light-weight cars.
Owners - Before doing any work on the car, decide how weight will be
added to the car, and then create any needed weight holes/pockets
first. This will eliminate lots of grief at the weigh-in.
CAR IS NOT LUBRICATED
This is the second most common problem I have seen. I used to be very
concerned about this and would work with folks to get some lube on
their car. But it is very difficult (and messy) to effectively
lubricate after the car is assembled. So, in recent years, I just ask
them if they want to add lubricant, and then loan them a tube of
graphite if they say yes.
Officials - Have a few tubes of graphite on hand, and identify a
location where the race owners can use graphite (typically outside the
Owners - Lubricate the wheels and axles before putting them on the
CAR IS SIGNIFICANTLY OVER WEIGHT
I'll never forget the Bus. The family glued another block of wood on
top of the original block and then carved and painted the body to look
like a school bus. The only problem was that the second block of wood
was not pine, but was instead fir, a much denser type of wood. The Bus
weighed over 7 ounces! To make the car legal, the dad had to hollow
out a large portion of the vehicle.
The point is that depending on what is used for weight, removing more
than a few tenths of an ounce can be a difficult problem.
Officials - The method to remove weight depends on the type of weight:
- Lead - Remove lead with a drill and drill bit. Lay the car on a
clean rag, and slowly drill into the weight area. Collect and properly
dispose of the lead fragments.
- Hard metals embedded in body (steel, tungsten, zinc) - Avoid
drilling into hard metals. The amount of pressure required to remove
material will likely damage the car. Instead, try to drill around the
weight and then use a small chisel to pry out individual weights.
- Zinc plates - Remove the zinc plate, and snap off pieces of the
weight with pliers. Weigh the material before reattaching.
Owners - Weigh the car body along with the weight, wheels, axles, and
any accessories early in the process. This will allow time to make any
needed weight corrections.
WEIGHT HANGS TOO FAR BELOW THE CAR
Typically clearance problems occur due to weights attached to the
bottom of the car. In one recent case at our weigh-in, a zinc plate
was screwed onto the bottom of the car with the wrong type of screws
(the original screws were lost). The weight itself cleared, but the
Officials - Make sure to check for car clearance. If the car just
barely does meet the specification, and you know that there is plenty
of clearance on the track, you can choose to let the car race.(1) But
if the car clearance is far from the specification, make sure the
problem is fixed. Otherwise, the car may drag, scratching the track
and performing poorly.
Owners - Make sure your car meets the specification before coming to
CAR IS OVERSIZED
At one of our races, a family came to the weigh-in that had not
previously registered (so they had not been given a copy of the
rules). Their car (actually a boat) was really neat! It was nicely
detailed, but had a mast and a bowsprit (a spar projecting from the
bow of a vessel) that caused the car to be too tall and too long. We
decided to allow the parts to stay on for the design judging, as long
as the parts could be easily removed by the race officials prior to
the racing. We have also done this for a few other cars with tails and
Officials - Make sure that the rules clearly define what is allowed,
and provide the rules to all participants. Then enforce the rules.
You may want to clarify in the rules whether accessories can be added
for the design judging that cause the vehicle to exceed the size
Owners - Make sure your car meets the specifications before coming to
Gorilla glue is a relatively new type of construction cement. It is
activated by moisture in the air or on the surface to be glued. When
it is activated, it foams and expands. This probably works well for
construction, but is generally a disaster for pinewood derby cars.
At a recent weigh-in a family brought in three completed cars, all of
which had Gorilla glue foam on the wheels. Apparently, they used it to
glue the axles in the slots, but then later found that the glue
essentially took over the car! I gave them some replacement wheels and
axles, and they did their best to repair the cars.
Unfortunately, the family brought along the bottle of glue, and
someone else used it to glue tungsten cylinders into holes drilled in
the bottom of the car. They turned in the car, and we left if lying on
its back for the glue to dry. As the evening progressed, the tungsten
cylinders slowly rose out of the holes. I shoved them back in a few
times, and finally they stayed in. But if I had not been watching the
car, the glue would have cured with the cylinders extending out about
a 1/2 inch, and the car would not have been able to run.
Officials - Ban Gorilla Glue from the weigh-in.
Owners - Don't use Gorilla Glue on your car.
The issues that can arise at weigh-ins are certainly many, and not all
of them can be anticipated. But as an official or owner, preparing for
these common issues will facilitate a smooth and (relatively) painless
(1) For our race, we allow zinc plates to be attached to the bottom of
the car, even though the clearance specification is not quite met. I
know that cars with zinc plates run fine on our track. These plates
are very convenient for correcting weight issues at the weigh-in, and
banning them would be like shooting yourself in the foot.
(2) Maximum Velocity offers zinc-plates for considerably less than
hobby shops. You can find them Here.