The BSA Pinewood Derby “rules” are generally treated as guidelines by most regional race committees. What might be prohibited in one race might be fine in another. The following rules are typical across many races, but you should check your local race regulations. Most races have at least a couple special additions or modifications.
- Total finished car weight cannot exceed 5.0 ounces.
- The scale used by the race officials provides the final race weight.
- Total car dimensions cannot exceed 7” in length, 2.75” in width and 5” in height. Note that height limits change depending on the clearance of finish gates.
- Clearance dimensions are as follow: 1.75” between wheels and 0.375” beneath body.
- The wood block provided in the kit must be used in the car.
- The wheels and axles supplied with the kit must be used. Seams can typically be removed from wheels but NOT tread. Axles may be polished to remove stamp marks, crimp marks or other imperfections.
- The car must be freewheeling, with no starting devices, mechanical speed enhancers, springs, or wheel bearings.
- No loose material of any kind can used on or in the car – including weights.
- All weights and other attachments must be properly secured to the car.
Again, those are the basic rules that most contests start with. Recent years have seen modifications to individual races including:
- Any use of lead must be securely sealed so it does not come into contact with anyone.
- Wheels cannot be shaved or lightened or otherwise altered by milling or drilling in any way.
- Axles must not be intentionally canted or bent to alter the contact surface of wheel to track.
- The car may not employ any unfair advantages such as notching the front, or adding upper bars, to get a head start.
Understanding the Pinewood Derby Rules and Regulations
Knowing the rules and understanding them are not always the same thing. If ever in doubt about the interpretation of a rule, just ask the local race committee or commissioner. Following are some of the most common questions about rule interpretation, along with their answers.
Also check the official BSA Pinewood Derby website for the rules any time.
Is the 5” height limitation for the body or finished car on wheels?
The height limit for any race is the overall height of the finished car in race-ready condition. The finish line is usually a gate that the car must pass under. Just over five inches is the typical gate clearance from the track surface to the underside of the gate.
1. Can I place weights under my car if I have the 0.375” clearance (3/8”)?
Yes. In fact, having weight beneath the car is best when possible. This positioning will add both speed and stability with all other things being equal.
2. Which end of the car is the front?
There usually is no rule or regulation about one end of the other of the block being the front, however you get more advantage from having the rear wheels close to the back of the car. This will allow for weight placement that adds speed as well as wheel placement that provides greater stability.
3. Am I limited to ONLY using the wood block in the kit?
This is kind of a trick question and comes up a lot. You must use the regulation block that comes in the kit as the frame of the car and where the wheels connect via axles. Other than that, you can typically add other types of wood for fenders, spoilers, and more. Balsa is a common choice since it is so light and easy to work with.
Pro Tips to Get the Most Benefit from the Rules
Why so much focus on the rules? Because you need to understand these before you plan any modifications. But I can boil it down to two big ones…
- The most important thing to know is do all wheels, axles, and blocks need to come from the official BSA Pinewood Derby kit?
- The second most important piece of information is to what extent you can modify any of those components.
We are not looking for loopholes or technicalities to gain an unfair advantage. We are just trying to be smart and engineer the car according to the regulations everyone must follow. Pinewood Derby races have been running for decades with millions of participants. The rules are modified as needed, when needed. You should take advantage of your ability to engineer a fast car – just like everybody else.
It Starts with a Kit
One way to keep the playing field even is to require all participants of the race to work from identical Boy Scouts of America Pinewood Derby Kits. This is more important than it sounds. There are a lot of “derby kits” that are NOT licensed by the BSA. Using one of these can get you disqualified before your car ever touches the track.
Official Pinewood Derby Block Size and Weight
The Pinewood Derby block is 7” long x 1.75” wide x 1.25” high and weighs 3.4 OZ +/-. It has two grooved slots for accepting full-length axles or nails in the bottom of the car body. The rear axle slot is located 15/16” from the back. The front axle groove is positioned 1-11/16” from the front. This leaves a span of 4-3/8” between the axles.
Pinewood Derby Block Dimensions
| Dimension | Inches | MM |
| Length | 7.0” | 177.8 mm |
| Width | 1.75” | 44.45 mm |
| Height | 1.25” | 31.75 mm |
Block Weight: 3.4 oz. US +/- or 96.4 grams +/-
Finished Pinewood Derby Car (Maximums)
Maximum Pinewood Derby Car Block Dimensions and Weight (Standard Rules)
| Dimension | Inches | MM | Notes |
| Length | 7.0” | 177.8 mm | End to end |
| Car Width | 2.75” | 69.85 mm | Side to side |
| Wheel Clearance | 1.75” | 44.45 mm | To straddle guide rail |
| Clearance Under Body | 0.375” | 9.525 mm | To clear guide rail |
| Height | 5” | 127.0 mm | To fit under finish gate |
Max Finished Car Weight: 5.0 oz. US or 141.748 grams
The following image shows what the axle groove looks like from the underside of the car. It is just a straight channel running from one side to the other.
Be Sure Your Block Is “Regulation” Before You Begin
There are several manufacturers of “derby kits,” but only one official Boy Scouts of America kit. That is purchased from the BSA organization. Other kits may not have BSA wheels, axels or even be the exact type of wood.
It is easy to tell the difference between official BSA wheels and others. Having an unapproved type can get your car disqualified before it ever hits the track.
It’s a bit tougher to tell with axles, but to the trained eye it can be apparent.
As far as wood type, licensed BSA pinewood blocks are normally yellow pine. It’s cheap and easily accessible. For the most part “wood is wood” once it has paint on it. But, for those that use shellac, clear-coat, or no coating at all – the wood type is obvious by its grain. I mention this because a lot of the pre-made cars I see for sale on Etsy, Ebay, and custom derby shops are made from other light-colored woods such as Poplar. Any experienced race inspector will spot that a mile away if the wood grain is visible.
Why is Poplar Popular?
Why do some people use Poplar? Poplar is a hardwood and more expensive than pine. But it is also very lightweight, and cuts clean with a laser. You can go to Lowes or Home Depot and get a ¼” thick poplar board that can be expertly cut and shaped in minutes with a 25-watt laser. Glue tungsten onto and just under the chassis and have a streamlined racer in no time.
How do I know? I have built dozens exactly like that for non-BSA derbies using my Pinnacle Laser machine. They work great. If you are in a derby race that allows you to use other than a specific pinewood block as a base, ¼” poplar is a great way to go. You can cut it by hand. With a coping saw, or a router.
Find Out If You Are Required to Use the Provided Axle Slots Pre-cut in the Car
The pre-cut axle grooves are sometime not cut at a true 90 degrees to the car body. This means wheel alignment will be far more difficult. If your kit appears to have axle grooves at other than a ninety-degree angle, try to swap the kit for another or see of you are allowed to flip the block and bore new axle holes.
Pro Tip: Some races require you to use the axle grooves even if you “true” it using a #44 drill bit at the groove top.
Drill New Axle Nail Holes
If you are allowed to drill your own axle holes, flip the block over and start fresh by drilling new axle receptors. Use a 2.2 mm drill bit (#44 bit) to place the axle holes where your wheel will go. The exact dimensions are available here.
| Axle Positions | Inches | Decimal |
| Distance from Front | 1-11/16” | 1.6875″ |
| Distance from Rear | 11/16” | 0.938” |
| Distance from Bottom | 1/8” | 0.375” |
Note: All distances are to center of axle hole
Pro Tip: The 2.2 mm bit (#44) provides the ideal axle diameter size. Drill bits can also be found in 2 mm and 2.1 mm; however, they might require too much force when pushing in the axles.
Pressing too hard or using even a tiny upholsterer’s hammer can split the brittle pine block so close to the bottom edge (1/8” from the bottom). You want to be able to press the axel in with your thumb or a flat edged tool.
So Many Ways to Win by the Rules
Following the Pinewood Derby rules in a way that lets you build a car that you can be proud of is what this is all about. And remember, it’s not just about speed. The same derby rules and regulations apply regardless of the category you want to dominate. From “best paint job” to “most original” there are nearly 100 used in contests across the US.
Pro Tip: You don’t need to spend a fortune to build a car that can win in any category – including speed.
You can also check youtube video on Derby Axles rules-
If you have shopped around, you know that tungsten weights cost an average of five dollars per ounce while tungsten putty is nearly nine dollars. Before you go spending twenty dollars on weights, take a few minutes to check out another article on this site: Pinewood Derby Weights for Pennies an Ounce. You’ll be glad you did.
Last update on 2023-10-26 / Affiliate links / Images from Amazon Product Advertising API