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Pinewood Derby Stories and Photos from Maximum Velocity
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Rule Gripes
I receive lots of questions and comments from our readers about rules. Many
times the person is asking me for the rules for their race, or for a
clarification on a point. Sometimes, the person is griping about the rules,
especially when the race leader appears to them to be misinterpreting the
local rules.
In these cases, I can't do much more than lend a sympathetic ear. Local
rules are out of my control, and I certainly can't jump in the middle of a
rule dispute. But during these times I certainly do wish that the local
race leaders would take the time to document a clear set of rules. So much
miscommunication, grief, griping, and anger would be mitigated by giving a
clear set of rules to the race participants well before the race event. (1)
But there is a more fundamental question that needs to be answered when
establishing rules. Even if the rules for the local race are clearly
documented, a valid question is 'Why?' Why is a particular technique
allowed/banned? What is the rationale for allowing (for example) an
extended wheelbase? Why do we need to have 4 wheels on the ground? Of
course this list goes on.
In today's article I would like to explore several common areas of pinewood
derby design that are oftentimes regulated, and offer some guidance as to
whether these design techniques should or should not be restricted.
GENERAL GUIDELINES
The purpose for rules is to make sure that the cars entered in the race:
1. Will run properly on the track (proper width, height, etc.)
2. Will not damage the track (too heavy, improper materials)
3. Maintain a level of equity. These arbitrary limits - such as the five
ounces maximum weight - are imposed to limit the range of options, thus
maintaining a level of competitiveness.
4. Only use techniques which are commonly available to the other entrants.
Furthermore, the rules need to be in line with the rules of parent
organizations when participants at the local level will be moving on to
district level races.
Let's take a closer look at several rule areas
MODIFIED WHEELBASE
There are many advantages to longer wheelbase cars (see Volume 2, Issue 6 -
"Modifying the Wheelbase"). So, should extended wheelbase cars be allowed
in all races? Let's look at the criteria from above:
Criteria
1. Yes - the car will run properly.
2. Yes - no damage to track.
3. Yes, required for equity. A long wheelbase car has a distinct advantage
over shorter wheelbase cars.
4. Yes - anyone can extend the wheelbase using a hand drill(2) or drill
press. But some expense is involved.
Conclusion
Disallowing extended wheelbase cars is a limit set to maintain competition.
If the local club allows wheelbase modification, then this should be
documented in the rules so that participants know that they are allowed to
modify the wheelbase. Also, the means to extend the wheelbase should be made
available to all participants at a workshop. By the way, some organizations
run two classes of cars: "Stock" - standard wheelbase only, and "Open" -
Extended wheelbase allowed.
LUBE TYPE
Many different lubes have been successfully used on pinewood derby cars,
including dry lubes (graphite and PTFE), liquid lubes (Krytox 100 and
Silicon), and some unusual ones (Pledge furniture polish, Armor All, and
Talcum powder). (3)
Criteria
1. Yes - the car will run properly.
2. Yes and No - if used properly none of these lubes will cause damage. But
if used to excess, many of the lubes can stain the track (including
graphite).
3. No, not required for equity. Several different lubes can be used with
reasonable success.
4. Yes - anyone can select an alternate lube.
Conclusion
Limiting the lube to a particular type is an arbitrary decision. Certainly,
to protect the track the rules must specify that excess lube be removed
before the car is turned in. But limiting the lube to one type is not
necessary. Different lubricants are widely available, and in fact, the
choice of lube is an area where human ingenuity comes into play!
FOUR WHEELS ON THE GROUND
Having three wheels on the ground can be a speed advantage. But beyond
this, it is much easier to build a car with three wheels on the ground than
with four! Even when four wheels touch the ground, normally three of the
wheels hold the weight of the car while the fourth wheel just barely
touches.
Criteria
1. Yes - the car will run properly.
2. Yes - no damage.
3. No, not required for equity. Although there can be an advantage to
running a three-wheeled car, the amount of advantage will depend on the
design of the car.
4. Yes - in fact it is easier to run three than four on the ground.
Conclusion
Limiting the car to four wheels on the ground is arbitrary. Since it is
easier to implement, I strongly recommend allowing three wheels on the
ground.
LATHED WHEEL TREAD
Many car kits are equipped with wheels that are badly out of round. To
improve the performance, the wheels can be trued.
Criteria
1. Yes - the car will run properly.
2. Yes - no damage.
3. Yes, required for equity. Rounder wheels are faster.
4. Yes - anyone can true wheels (4). But some expense is involved.
Conclusion
Limiting the car to non-trued wheels does serve to maintain competition.
However, since many wheel types can be severely out of round (such as BSA),
groups should consider offering the means to true wheels at a workshop.
MODIFIED WHEEL GEOMETRY
The speed of the car can be improved by reducing wheel mass through tread
reduction. This can be done in many ways including drilling holes in the
wheels, and by narrowing the tread.
Criteria
1. Yes - the car will run properly.
2. Yes - no damage.
3. Yes, required for equity. Some modifications can greatly improve speed.
4. No - although they can be purchased, accurately modifying the geometry of
a wheel requires either special machinery and/or extensive trial and error.
Conclusion
Since wheel modification is beyond the ability of many race participants, I
recommend limiting wheel modification to 'Open Competition' races.
AFTERMARKET WHEELS AND AXLES
Aftermarket wheels are axles can improve the speed of the car.
Criteria
1. Yes - the car will run properly.
2. Yes - no damage.
3. No, aftermarket speed axles are not necessarily faster than well-prepared
kit axles.
4. Yes - Aftermarket parts are available, but an expense is involved.
Conclusion
The purpose of providing a kit is so that each participant uses the same
basic materials. However some kits provide axles that require extensive
work.(5) In these cases groups should consider offering aftermarket axles
to all participants.
CONCLUSION
There are certainly other rules that should be reviewed to determine whether
there is a basis for the restriction. I encourage all race leaders to
thoroughly review the local rules and make modifications where needed.
(1) In Volume 2, Issue 2 - "It's the Law! - A Sample Rule Set for Your
Pinewood Derby", I provided an outline for a complete set of rules. Just
fill in the blanks for your organization.
(2) The Pro-Body Tool is a drilling guide to accurately drill axle holes
with a hand drill. You can find it at: www.maximum-velocity.com/specialty_tools.htm#body
(3) I do not personally vouch for any of these products except graphite and
Krytox 100. For more information on these products, see: www.maximum-velocity.com/pinewood_derby_speed_supplies.htm#lube
(4) The Pro-Wheel Shaver is a device for truing wheels. For more
information see: www.maximum-velocity.com/specialty_tools.htm#shaver
In addition, trued wheels are available from many sources including Maximum
Velocity.
(5) One of my pet peeves is the nail axles in the BSA kits. Removing the
burrs is a difficult process for many people. Certainly BSA could include
axles without burrs at little to no cost increase. But until such a time,
people will continue to purchase aftermarket axles. An alternative is our
Official BSA Speed Axles. For more information see:
http://www.maximum-velocity.com/wheels_axles.htm#bsa_axles