There are six major factors that influence the speed of a Pinewood Derby car. Pay close attendtion to all six of these and you can build a winning car.
Major Speed Factors:
1. Body Design
2. Weight Placement
3. Wheel Preparation
4. Axle Preparation
Advanced Speed Techniques:
1. Rail Rider Alignment
2. Rear Wheel Canting
3. Advanced Friction Reduction
IV. Axle Preparation
BSA Kit Axles or Aftermarket BSA Speed Axles
The first thing you should do is decide on which pinewood axles you want to use. You can either use the stock axles that came with your Official BSA kit or you can use a set of pre-treated aftermarket BSA speed axles.
Using the BSA Kit Axles will require a good bit of work and preparation as we will discuss below. You must eliminate the burs, or crimp marks, on the axle shaft. Those must be removed to have any chance of first place. You will then need to put a high polish on the axle shafts and inside the axle head.
So let's first look at Using pre-prepared aftermarket BSA Speed Axles. These are Official BSA Pinewood Derby axles that have been machined on a CNC lathe to make them completely round and free of imperfections. They are then polished to some extent. Some axles have machined grooves in the shaft in order to reduce wheel to axle contact and to serve as storage wells or grooves (see photo) for graphite. Some pinewood derby axles are pre-coated with a layer of graphite to further lubricate the contact points. Using pre-prepared axles will save you a lot of time and effort. Plus you will have some very fast axles.
All aftermarket speed axles have been polished to some extent. However, for the ultimate axles you will likely need to fine polish them even more with the use of sandpaper all the way up to 12,000 grit and then finish them off with a polishing compound and polishing cloth.
There are many differences of opinions on what type of BSA axles are the fastest. Many want a smooth surface on their axle shafts while others prefer grooves. Some folks like the pre graphite coated pinewood axles while others hate them. Many of these folks can produce statistics to support their point of view.
Regardless of the axle type, the most important this is to have an extremely high polished axle shaft that is well lubricated. Also, there are many other factors that make for a fast Pinewood Derby car. The best pinewood derby axles in the world won’t help if those other factors are not addressed.
Make sure that you understand what axle modifications are permitted by your pack rules.
Check out the Derby Monkey line of speed axles. CLICK HERE
How to Prepare Pinewood Derby Axles
If you decide to prepare your own axles you have a little work ahead of you. Using the BSA Kit Axles will require a good bit of patience and preparation.
Our purpose here is to explain a single axle preparation system that has been successfully used thousands of times. This is a simple and easy to understand system that will make your Pinewood Derby axles well polished and super fast.
The first thing you should do is to check and make sure your axles are straight. The best tools for this are a hammer and the Derby Worx Pro Axle Press. The Pro Axle Press will improve the speed of your pinewood derby car by performing three critical procedures on nail type axles:
1. Axle Straightening - Ensures accurate wheel tracking by creating absolutely straight axles. Improved wheel tracking equals greater speed!
2. Axle Rounding - Ensures accurate wheel rotation by creating absolutely round axle shafts. Improved wheel rotation equals greater speed!
3. Head Squaring - Ensures proper wheel rotation by squaring the axle head to the axle shaft. Improved wheel rotation equals greater speed!
4. Raised Wheel and Alignment Adjustments - When it is necessary to purposely bend an axle (to raise a front wheel or make an alignment adjustment), the Pro-Axle Press serves as a handy clamping device for holding the axle while making the bend.
Every experienced Pinewood Derby car builder agrees that polished axles are faster than the stock axles straight out of the kit box. However, not all builders agree on the best polishing method. There are many different axle preparation methods and many different axle polishing kits available on the market. Some are good and some are not.
You will develop a sense of accomplishment for performing the entire axle polishing process yourself. Remember, this is a time consuming process and your son will likely become bored long before the job is complete. Most dads end up doing the majority of the axle prep by themselves.
Now that you have straightened your axles and have boldly decided to perform the axle polishing yourself there are a few more decisions you must make before proceeding.
You must decide how fine you want your end polishing results to be. This is an area where many different opinions exist.
Most axle polishing processes use a series of fine grit sandpapers to polish the metal surface of the axle shaft. The abrasiveness, or coarseness, of sandpaper is usually expressed as “grit”. The lower the grit number the more course the sandpaper will be. The higher the grit number, the finer, or smoother, the sandpaper will be. So the higher the grit number of the last sandpaper used the smoother the axle shaft surface will be.
Some builders polish their axles by starting with 400 grit and finishing at 600 grit. This is very fast but does not leave a noticeably smooth surface. Some believe that the fine scratched left over from the 600 grit paper serves as tiny storage reservoirs for graphite.
Most builders polish their axles to a much more noticeable point by working up to 2,500 grit, 3,200 grit or even more. The extreme axle polishers use sandpapers with a grit value of up to 12,000 followed by a super fine metal polish of around 0.05 microns. Properly done, this leaves a mirror shine on the axle shaft.
The Best Axle Polish System
The best polishing system for Pinewood Derby car axles is the ProMax Axle Polishing Kit. This profesional grade polishing kit consists of a total of 10 sheets of Extra Fine Wet-Dry Sandpaper and 3M Ultra-Fine Polishing Sheets. You will also get one jar of Monkey Jam Premium Axle Polish, one micro-fiber polishing cloth and instructions on how to put a district caliber 60,000 grit polish on your Pinewood Derby axles.
Deciding how polished you want your axles to be will govern what supplies you will need to gather. The micro-fine sandpaper may be hard to find at your local hardware or automotive store so you might consider ordering the complete ProMax Axle Polishing Kit online. These kits are all premeasured and maximized for their full polishing potential.
If you want to make this process quick and easy then you might want to consider the Monkey Snot Axle Polishing Combo. If you want to polish your axles to the absolute max then you should think about the Ultimate Axle Polishing Kit for a mirror like finish.
The tools and supplies needed for axle polishing will include:
1. Small File: Required for filing away the crimp marks on the axle shaft and/or the inside of the axle head.
2. Drill: This can be a hand held drill, a Dremell type drill with a low speed or a drill press.
3. Fine Sandpaper or Axle Polishing Kit: The higher the desired polish the more sheets of different grit sandpaper you will need. A sensible set of incremental grits would be 400, 600, 1200, 1500, 2000, 2500, 3200, 3600, 4000, 6000, 8000, 12000. You might also need a fine metal polishing compound like Monkey Jam. Remember, a pre-assembled axle polishing kit will already have these in one package.
4. Bowl of Water: Its best to wet the sandpaper before applying it to your axle.
5. Denatured Alcohol: This works best for cleaning polish residue from your axles.
I. Remove Nail Crimp Marks
A. You must use a file and drill to remove the crimp marks on the nail type axle shaft.
B. Install the axle in the drill exposing about ½” of the nail shaft.
C. If using a hand held drill you will need someone to hold the drill or use a hand drill clamp.
D. Turn the drill on.
E. Gently place the flat side of file against the crimp marks on the shaft allowing the file to remove the marks.
F. Gently place the flat side of file against the crimp marks on the inside of the axle head to remove. (see fig. 2 below)
G. For added speed, file a slight shaft to head angle on the inside of the axle head. This will decrease the surface contact area between the axle head and wheel.
H. Check to make sure all riges are gone. (see fig. 3 below)
I. The best drill to use for this is the Dremel Rotary Tool and Dremel Workstation
II. Polish the Axles
A. Cut each sandpaper into 1/4" strips, about 3½" long.
B. Dip a strip of the 400 grit sandpaper in water.
C. Hold each end of the strip with the thumb and forefinger of each hand.
D. Apply sandpaper to the spinning axle for 15 seconds. (see fig. 4 above)
E. Polish the portion of the axle on which the wheel will spin.
F. Polish the inside of the axle head with same strip of sandpaper.
G. You will repeat steps IIA through IIF using each grit of sandpaper in order depending on how fine of a polish you have decided to place on your axle.
H. Repeat the above steps for each axle.
I. Clean axles well with alcohol.
III. Fine Polish the Axles
A. You now have the option to finish the process with a fine metal polish such as Monkey Jam.
B. Rub a liberal amount of Monkey Jam, or other fine metal polish, on a new ¼” strip of polishing cloth.
C. Rub cloth back and forth on axle shaft for about 15 to 20 seconds while the axle is spinning in the drill. (see fig. 5 above)
D. Be sure to polish the inside of the nail head.
E. Repeat the above steps for each axle.
F. Clean axles well with alcohol. Make sure all polishing compound is removed.