How To Build a Pinewood Derby Car/Rules

Table of Contents

• Home
• Preface
• Rules
• Block
• Wheels
• Axles
• Assembly
• Physics
• Appendices

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There is no single set of Pinewood Derby rules; each Pack, District or Council is free to set its own rules. However, car construction rules have appeared in some BSA publications. Many rules such as size, weight, bearings, bushings, and springs are common to nearly all Pinewood Derby rules. For example:

Dry Lubricant

Many rules sets specify dry lubricant only and some allow only graphite and Teflon explicitly. Other rules allow liquid lubricants as long as they are not wet at the time of the race.

Axle Modification

Some rules prohibit axle grooves and beveling. Most prohibit substitution of non-BSA axles (e.g. nickel-plated).

Wheel Modification

Some rules prohibit light wheels. This is typically worded as prohibiting removal of "substantial mass" and requiring that the inner wheel wording be visible. Some rules prohibit wheel coning or modification beyond light sanding. More detailed rules prohibit narrow wheels or those with one (V-tread) or two (H-tread) raised tread areas.

Wheel Mounting

There are three levels of wheel mounting rules: 1) no restriction, 2) original wheelbase dimension, 3) original wheelbase and axle slot (no new holes). In some cases, the raised wheel modification may be prohibited.

Aftermarket Parts

Most rules (e.g., the BSA rules above) do not preclude the use of aftermarket parts as long as they are derived from the BSA kit. For example, lathed wheels or grooved axles are acceptable if the parts originate from BSA kits. Some rules expressly prohibit this type of substitution, although enforcement can be problematic.

Ready Made Cars

It is generally regarded that ready to run cars violate the spirit of the Pinewood Derby even if they do not violate a specific rule specifying that the car be built substantially by the Cubscout. However, ready to race cars created from BSA kits can be found on eBay and other sites.

Rules in the box

Pinewood derby block, nails, and wheels.

The rules that come in the Grand Prix Pinewood Derby Kit (BSA Kit 17006) are known as the "Rules in the Box."

1. Car Specifications: Width: - 2-3/4"; Length - 7"; Weight - Not over 5 Ounces; Width between wheels - 1-3/4"
2. The car must have been made during the current year (year in which derby is being held) - Cannot use previous years cars - Pinewood Derby Car kits supplied by the pack
3. Wheel bearings, washers, and bushings are prohibited.
4. The car shall not ride on springs.
5. Only official Cub Scout Grand Prix Pinewood Derby wheels and axles are permitted.
6. Only dry lubricant is permitted.
7. Details, such as steering wheel and driver are permissible as long as these details do not exceed the maximum length, width and weight specifications.
8. The car must be free-wheeling, with no starting devices.
9. Each car must pass inspection by the official inspection committee before it may compete.
10. If, at registration., a car does not pass inspection, the owner will be informed of the reason for failure, and will be given time within the official weigh-in time period to make the adjustment.
11. After final approval, cars will not be re-inspected unless the car is damaged in handling or in a race.

Cub Scout Leader How-To Book

Green wedge with extended wheelbase.

Car construction rules from the "Cub Scout Leader How-To Book" (BSA No. 33832).

A lathed wheel

Cub Scout Grand Prix Pinewood Derby Guidebook

Bottom view of a wedge block with standard axle slots. The two side and three bottom holes are for weights.

Example Pinewood Derby car construction rules from the "Cub Scout Grand Prix Pinewood Derby Guidebook" (BSA No. 33721).

1. The car must have been made during the current year (the year in which the derby is held).
2. The width of the car shall not exceed 2-1/4 inches.
3. The length of the car shall not exceed 7 inches.
4. The weight of the car shall not exceed 5 ounces.
5. Axles, wheels, and body wood shall be as provided in the kit.
6. Wheel bearings, washers, and bushings are prohibited.
7. The car shall not ride on any kind or type of springs.
8. Any details added must be within length, width, and weight limits.
9. The car must be freewheeling, with no starting devices.
10. No loose materials of any kind (such as lead shot) are allowed in the car.
11. The official number must be clearly marked or visible on both sides of the car.

Wotamalo Rules

Bullet design with shaved and coned wheels, beveled and notched axles, and drilled axle holes.

Wotamalo District rules section on car construction.

Standard wheels (left) and one-gram light wheels (right)

1. Material:Race cars shall be constructed for this event from the parts contained in the Official Grand Prix Pinewood Derby Kit (referred to below as the kit) as sold by the Scout Service Center, [for the District in which the race is run]. Materials from the kit may be supplemented but not replaced.
2. Weight: Race cars may weigh no more than five (5) ounces (total weight) as determined on the official scales during race day inspection.
3. Wheels and Axles: The car shall roll on the wheels from the kit. The wheels shall turn about the axle nails from the kit. The axle nails shall be firmly affixed to the wood of the car body. The axle dimensions may not be changed substantially. The outside surface of the axle head (the non-contact surface) may not be changed substantially, such as, by polishing. It must be obvious to the judges that the wheels and the nails from the kit are being used.
4. Size: Race cars may be no longer than 7 inches, nor wider than 2 3/4 (2.75) inches, nor taller than 3 inches, as determined by the official gages during race day inspection. (Underside clearance of at least 3/8 (0.375) inches and inside wheel to wheel clearance of at least 1 3/4 (1.75) inches is recommended, so that the car will run on the racetrack. Adequate clearance is the responsibility of the race car builder.)
5. Weights and Attachment: Weight may be added to the car and will be considered part of the car for purposes of all measurements. "Weight" is considered to be any material on the car that is not provided in the kit. All weight must be securely fastened to the car, e.g., by permanent glue, nails or screws, but not by "sticky substances", e.g., tape, or tack spray. Weights shall be passive, i.e. non-movable, non-magnetic, non-electric, non-sticky, etc.
6. Wheels: Wheel treatment (hub and tread smoothing and polishing) may not result in substantial removal of mass nor in reducing the tread (track contact) width from the original kit wheels. Wheel tread surface must be cylindrical. The words "Official B.S.A. Made in U.S.A." and other lettering on the wheels shall remain intact and clearly visible to the inspector. Some of the original "tread marks" on the wheel face must be intact, i.e. apparent to the inspector.
7. Unacceptable Construction: The following may NOT be used in conjunction with the wheels or axles: hubcaps, washers, inserts, sleeves, bearings.
8. Gravity Powered: The race car may not be constructed or treated in such a way that the track's starting mechanism imparts momentum to the car. (For instance, this provision disqualifies cars with sticky substances on the front of the car and protrusions which may catch on the starting pin.)
9. Lubricants: Lubricants must be dry at the time of inspection and racing.
10. Staging: The entire car must stage behind the starting pin.
11. Body: The car body may have no moving parts.

Pack 254 Rules

Nyoil liquid lubricant.

From the Virtual Cub Scout Leader's Handbook, these are a stricter version of the Watamalo Rules.

A stick-on axle bushing.

1. Material: Race cars shall be constructed for this event from the parts contained in the Official Grand Prix Pinewood Derby Kit (referred to below as the kit) as sold by the Scout Service Center, [for the District in which the race is run]. Materials from the kit may be supplemented but not replaced.
2. Weight: Race cars may weigh no more than five (5) ounces (total weight) as determined on the official scales during the pre-race check-in. Note: The official scale will be available in the Palmer School office from January 4th until registration.
3. Wheels and Axles: The car shall roll on the wheels from the kit. The wheels shall turn about the axle nails from the kit. The axle nails shall be firmly affixed to the wood of the car body, and MUST be placed in the original 'axle grooves' in the supplied wooden block. It must be obvious to the judges that the grooves, wheels, and the nails from the kit are being used.
4. Size: Race cars may be no longer than 7 inches, nor wider than 2-3/4 (2.75) inches, as determined by the official gages during the Registration and Inspection. Underside clearance of at least 3/8 (0.375) inches and inside wheel to wheel clearance of at least 1-3/4 (1.75) inches is recommended, so that the car will run on the race track. Adequate clearance is the responsibility of the race car builder.
5. Weights and Attachment: Weight may be added to the car and will be considered part of the car for purposes of all measurements. "Weight" is considered to be any material on the car that is not provided in the kit. All weight must be securely fastened to the car, e.g. by permanent glue, nails or screws, but not by "sticky substances", e.g. tape, or tack spray. Weights shall be passive, i.e. non-movable, non-magnetic, non-electric, non-sticky, etc.
6. Wheel Treatment: Wheel treatment (hub and tread smoothing and polishing) may not result in substantial removal of mass nor in reducing the wheel width from the original kit wheels. Some of the original "tread marks" on the wheel face must remain intact, i.e. apparent to the inspector. Wheels may not be machined to a beveled condition and the portion of the wheel surface that contacts the track must remain parallel to the axle.
7. Unacceptable Construction: The following may NOT be used in conjunction with the wheels or axles: hubcaps, washers, inserts, sleeves, bearings.
8. Gravity Powered: The race car may not be constructed or treated in such a way that the track's starting mechanism imparts momentum to the car. (For instance, this provision disqualifies cars with sticky substances on the front of the car and protrusions which may catch on the starting pin.)
9. Lubricants: Only dry lubricants such as graphite or powdered Teflon "white lube" will be allowed for lubricating the wheels. Lubricants may not foul the track. There will be a lubrication table set up at the race. In the interest of fairness, only one lubrication is allowed before the beginning of the first heat race and then once again before the beginning of the first race of the semi-finals and finals.

Table of Rules

An aftermarket coned and notched axle.

Application of Common Rules

Rule	Yes	No
Must use BSA kit	B, H, P, W, 2
Must use kit supplied by Pack	W, 2	B, H, P
Must use stock axle slots	2	B, H, P, W
Must use stock wheelbase	2	B, H, P, W
Wheel coning is allowed	B, H, P, W, 2
Light wheels are allowed	B, H, P	W, 2
V and H tread wheels are allowed	B, H, P	W, 2
Axle beveling/tapering is allowed	B, H, P, W, 2
Axle grooves are allowed	B, H, P, W, 2
Wet lubricant allowed	W	B, H, P, 2

B = Rules in the box

H = How to book

P = Pinewood derby guidebook

W = Wotamalo Rules

2 = Pack 215 Rules