Building KubKars

c10xKubKar racing is a 30 year old tradition in the Scouting movement. It allows Cubs the chance to design a vehicle starting from a block of wood, carve or cut it into a desirable shape and then race it against other Cubs. Cubs learn how to use woodworking tools and important aspects of woodshop safety while under the supervision of leaders and adults. The work can qualify for badge requirements such as the Tawny Star, the Carpenter Badge and the Handicraft Badge. The Cubs take pride in their efforts, and look forward with enthusiasm as they pit their car against others in their pack or visiting packs. The following describes important aspects and standards in the design of a KubKar. Leaders and Scouts can enter Pickup Trucks and 18 Wheel Trucks.



The following specifies the design of KubKars, Pickup Trucks, 18 Wheel Trucks and KubKar Race Tracks as well as tips to improve a KubKar's performance.

  1. If you want you can download two Excel 2000 spreadsheets that scores KubKar events using 3 or 4 KubKar lanes.
  2. A complete planning guide for a KubKar event is also prepared showing:
    1. Event Information
    2. Participants
    3. Tasks to be filled by volunteers
    4. Equipment needed
    5. Proposed schedule for the day
    6. KubKar Challenge rules
    7. KubKars and trucks construction specifications
    8. Restrictions
  3. Excellent KubKar links can be found at the ABC Pinewood Derby Site or at The Ultimate Pinewood Derby Site
  4. General Rules: All cars must start by gravity from a standstill, at the starting point. No pushing is allowed. The car whose nose is the first to cross the finish line is the winner. The race official will decide the winner, and if the result is too close to call, a second race can be run. If any car leaves the track the race can be restarted. If the same car leaves again, the car is eliminated.
  5. There are 25 things that could happen at a KubKar Rally.


Wheel Bearings, washers and bushings are prohibited. The car shall not ride on springs. Details and attachments may be added providing they are securely fastened and do not exceed the maximum length, width and weight specifications. The car must be free-wheeling and may only be propelled by the force of gravity. KubKars are subject to inspection by an official inspection committee to determine eligibility.


Mark your chosen design on the top and the sides of the block. Carefully carve or cut to the desired shape. Sand smooth. Paint, stain and/or finish as desired, preferably with water based treatments. Insert axle through the wheel and force into slots provided. The wheels should spin freely. Racers may wish to lubricate axles and wheels using (dry) powdered graphite.


Details are important. Take into consideration the following:

1. wheel alignment,
2. axle and wheel lubrication and honing,
3. weight distribution,
4. car design,
5. a high gloss finish.

1. First and foremost, is the wheel alignment, which is necessary to obtain a straight smooth run, thereby reducing wheel friction on the guide track rails. Roll your car along the kitchen floor. If it veers to the right or left too much, the axles are crooked. Just like steering a car, you need to adjust the steering on your Pinewood Derby Car. To do this, you must adjust one or more of the axles so the car rolls straight. You can do this by re-drilling the axle holes and re-inserting the axles.
2. Next in importance is reducing wheel and axle friction. You want to make your axles as smooth as possible. Be absolutely sure that the burr under the nail head is filed or sanded off. Once that is sanded off, polish the nail head to a mirror like finish. Purchase a tube of graphite and sprinkle a little on the axles near the wheel. Spin the wheel so the graphite works in. You will notice a significant improvement in the speed of the wheel as it turns. Do not use regular oil or silicon, since this may soften the plastic.
3. Be sure your car weighs as close to 5 oz as possible. The heavier your car, the faster it will go. Find someone with a scale, purchase an inexpensive scale or weigh your car at the post office. Add weights until the car with the wheels and axles is up to 5 oz. Don't wait until race night to get this right. One can carve out the inside of the KubKar and insert metal washers or bolts to bring the weight of the car to its maximum. Some feel that if one places the car weight to the end of the car, the stored potential energy in the race will make a faster car.
4. First step is to have fun thinking up a car design. Use your imagination. Be creative. Shape has the least to do with winning. A beaver driving a log or even a pickup truck is more interesting than a wedge and will be just as fast. The aerodynamics of a small block of wood doesn't mean much in thirty feet. Don't limit your imagination, but keep in mind that the more complicated the design, the harder it will be cut the pine block and shape the car.
5. Apply several coats of sanding sealer, then sand entire car with a fine-grade sandpaper. Give the model at least two coats of fast-drying paint. When the paint is completely dry, sand with a fine sandpaper, apply a final coat of paint and allow to dry thoroughly. Rub entire vehicle with a rubbing compound. Apply a coat of auto wax and rub to a high gloss finish.


* WIDTH: Overall width including wheels is not to exceed 7 centimetres or 2-3/4 inches. The minimum distance between the wheels is 4.5 cm or 1-3/4 inches.
* WEIGHT: Overall weight is not to exceed 142 grams or 5 ounces.
* CLEARANCE: Clearance between the chassis and the track should be 0.95 centimetres or 3/8ths of an inch.


* 1 Block of wood 17.8 cm (7 inches) long, 4.5 cm (1-3/4 inches) wide, 3.2 cm (1-1/4 inches) high
* 5 Black plastic wheels, 3.2 cm (1-1/4 inches) in diameter
* 5 Steel pin axles
* 1 Decal sheet
* 1 KubKar designer ribbon
* 1 KubKar Kit instruction sheet


* WIDTH: Overall width including wheels is not to exceed 7 centimetres or 2-3/4 inches. The minimum distance between the wheels is 4.5 cm or 1-3/4 inches.
* WEIGHT: Overall weight is not to exceed 142 grams or 5 ounces.
* CLEARANCE: Clearance between the chassis and the track should be 0.95 centimetres or 3/8ths of an inch.


o Truck Cab: Overall width including wheels is not to exceed 8.6 centimetres or 3 3/4 inches.
o Truck Trailer: Overall width including wheels is not to exceed 9.5 centimetres or 3 3/8 inches.
o The minimum distance between the wheels is 4.5 cm or 1-3/4 inches.
o Truck Cab: Overall weight is not to exceed 255 grams or 9 ounces.
o Truck Trailer: Overall weight is not to exceed 450 grams or 16 ounces.
* CLEARANCE: Clearance between the chassis and the track should be 0.95 centimetres or 3/8ths of an inch.




* Truck Cab: 1 Block of wood 7.6 cm (3 inches) long, 4.5 cm (1-3/4 inches) wide, 5.1 cm (2 inches) high
* Truck Trailer: Masonite wood panels forming a 6 sided box 30.5 cm (12 inches) long, 8.5 cm (3-3/8 inches) wide, 8.5 cm (3-3/8 inches) high
* Truck Cab Wheel Base: 1 Block of wood 17.8 cm (7 inches) long, 4.5 cm (1-3/4 inches) wide, 1.9 cm (3/4 inches) high
* Truck Trailer Wheel Base: 1 Block of wood 8.9 cm (3-1/2 inches) long, 4.4 cm (1-3/4 inches) wide, 1.9 cm (3/4 inches) high
* Misc Parts: 18 Black plastic wheels, 3.2 cm (1-1/4 inches) in diameter, 10 Steel pin axles (2 on cab front, 4 on cab rear, 4 on trailer rear), 2 Dowels for smokestack, 1 Centre Pin


Category     KubKar/Pickup Truck     Truck Cab     18 Wheel Truck Trailer
Maximum Weight     142 grams/5 ounces     255 grams/9 ounces     450 grams/16 ounces
Maximum Length     17.8 cm/7 inches     20.5 cm/8 inches     33.0 cm/13 inches
Overall Height     Unlimited     Unlimited     Unlimited
Maximum Outside Width     7.0 cm/2 3/4 inches     8.6 cm/3 3/8 inches     9.5 cm/3 3/4 inches
Maximum Width Between Inside of Wheels     4.5 cm/1 3/4 inches     4.5 cm/1 3/4 inches     4.5 cm/1 3/4 inches
Minimum Clearance Between the Chassis & the Track     0.95 cm/3/8 inches     0.95 cm/3/8 inches     0.95 cm/3/8 inches
Wheels and Axles     Scouts Canada/Kit Issue     Scouts Canada/Kit Issue     Scouts Canada/Kit Issue



Check your local Scout Shop and/or the official Scouts Canada catalogue for KubKar accessories and presentation items. Items include templates and decals, accelerator and tubular weights, crests, pins and trophies
Ordering Kits (Catalogue Number: Car: 71-100, Truck: 71-202):
Kits can be ordered from your local Scout Store or by writing to:

# Scouts Canada
# Box 5151 Station LCD-Merivale
# 1345 Baseline Road
# Ottawa, Ontario, Canada, K2C 3G7
# Tel: (613) 224-5131
# Fax: (613) 224-6022


* The length should be suitably long enough to allow the cars to accelerate and maintain speed. Some cars start fast, others maintain speed better. The best cars do both. The starting gate should be made so that all cars start at the same time. A lane strip is used to force the cars to follow a set path down the track. Sufficient cushioning should be placed at the end of the track to catch the cars and thus avoid damage.
* For ruggedness, permanent joints should be glued with white glue and screwed. All wooden components should be block sanded to remove any splinters before assembly.
* After cutting the four track sections, glue and nail a strip of 1/2"x3/16" flat moulding along the edges to protect both the track and curious hands. The lane guides are the last parts to be assembled because all attachments, supports and so on, should be under these rails. Make a jig to position the three rails exactly, and measure from the same side of the sections at various points to ensure perfect alignment.
* The sections are held together with 3/4"x2" hardwood cleats. They should be fastened under the outside lanes with glue and 1-1/2" flat head screws. Two-inch stove bolts with butterfly nuts are best for connecting the sections together. The two end sections should be mounted on 1"x2" runners to provide clearance for the nuts, and a stable, flat base for the track. To ensure a smooth and even race, sections must fit together with precision, Sand and shape the interfacing parts to eliminate any mid-run bumps.
* The curved sweep on the ramp bends naturally into a smooth starting ramp. It will probably be necessary to weight the short legs with a bag of sand to keep the track on the floor. Paint the track with either a urethane varnish or a high gloss enamel.
* The track should be about four feet high at the starting gate. The finishing line is usually at ground level but you might consider raising the whole track several inches for better visibility.
* The track should slope from about 30 degrees at the start line changing gradually to 0 degrees about 12 feet from the start line then another 16 feet of flat track to the finish line. The remainder of the track is an overrun area to allow the cars to slow.