Fast Pinewood Derby Speed Wheel – Asset wheel by Derby Dust
Derby Dust Asset Wheel
To the novice builder there can be great confusion in wheel choice. What does all this technical info mean? What does my Pack allow? There is no blanket BSA rule that cover all wheels. Each local PACK determines what wheels can and cannot be used.
Below is a run through of each wheel we offer with the as much info as we can provide. If you have a properly tuned car, then speed will be based mostly on wheel weight. The lighter the wheel, the faster the car. Proven concept, not mathematical.
Please take note that wheels are massed produced through an injection molding system. There are too many factors to mention why each wheel is its own unique wheel as much as we want them to be the same. They are not machined from a solid mass. This just means that every wheel is different.
Only one company makes the wheels, everyone else machines them to make them faster. Every company that machines wheels tries to make the sweetest lemonade they can make based on an average. There will always be outliers. If you think you have an outlier, please contact your wheel manufacturer prior to leaving feedback.
I am more than positive no matter who machined your wheel they will make it right. The industry needs this leeway to continue to grow.
Derby Dust is the first to offer a flawless wheel hub. We saw a need to make a new wheel because of the new rules at the pack level. We asked ourselves how can we provide a better wheel if everyone has to play by the same rules. If the wheels must remain basically the same weight as factory, what can we offer to make sure you still have a leg up in the mix. We have had great results with this wheel set.
All measurements are averages and may not be actual per your specific wheel.
AWW- Average Wheel Weight
MIB- Matched Inner Bore +/- 0.0005″
OD: 1.174″ Bead/Tread present (target goal may be +/- .001″)
AWW: 2.56 grams ( ranges being from 2.53-2.61)
Outer Hub: 2 Step, concave head (allows reduced wheel gap)
Inner Wheel Edge: Factory
Inner Wheel Hub: Factory
Inner Hub Bore: Flawless Bores
This wheel has had the outer diameter reduced by machining with CNC lathe for a uniformed tread consistent with the alignment of the hub. Custom delrin chuck ensures no damage done to the wheel. It will have bead/tread present. Flawless Inner bores. The wheels have been sorted for any manufacturing flaws. Meet most pack requirements. However, it will not meet the 1.180″ outer diameter requirement. All BSA lettering in tact. MM, MIB available.
Pinewood Derby Wheel INNER BORE
First process in determining whether or not a wheel can make this cut is the inner bore. We first inspect the inner bore using a digital inspection scope.
Only wheels with flawless inner bores are used for this wheel set. Because of this quality control, only 2 out of 10 wheels will meet this requirement. Even the big named wheels do not have this type of quality. This ensures you have the best possible wheel to start with.
There is no need in doing all the following modifications if your wheel fails at this requirement.
Pictures are of wheels that did not meet our standards. Many wheels have this void straight from the factory which causes unknown wheel travel, binding and wobble. It is caused by the ejection pin from the injection molding process.
Derby Dust Asset Wheels have an inner hub free of voids.
Pinewood Derby Wheel Tread
The next step is to make a uniformed, flat tread as addressed by most packs. Mold marks are removed while retaining near full tread/beaded edges. Outer wheel diameter will always be 1.170 or greater because of our machining process. Milled using CNC lathes makes the treads nearly identical to factory casting. We have a dedicated lathe for this process. The axis is fixed and never moves. What this means is that all wheels that we produce have the most consistent repeatable wheel that we can offer. There is no other way to do this. We can control all the variables. By doing so, rough edges are not present on our wheel tread.
Compare the outer treads of these three wheels. First is stock, the second is the leading aftermarket seller, the last is ours. Even the most expensive aftermarket wheels have this tell-tale sign. With that in mind, we figured out a way to machine our tread to near identical to uncut wheels.
For the 2016 season, we have now improved this process by replacing the mandrel with a dedicated delrin chucking system that grabs the wheel by the inner hub. This ensures that machine work done is parallel to the hub and that any and all wheel wobble is now almost always eliminated. There is always an outlier.
This process has to be done with a CNC machine. If you try to do it by hand then you get a cut in the wheel similar to the one in the middle. It’s called the fingernail test by the experienced judges. Run your fingernail across the wheel and if you can feel the grooves, then you know it was machined.
Pinewood Derby Wheel Go / No Inspection
To keep this wheel compliant with 99.99% of packs. We have to address the following.
We do not reduce the width of the wheel. Since most packs do not allow this modification. Most are very descriptive about this modification.
We do not true the edges as that changes the width of the wheel which makes it illegal according to 90% of the pack rules.
We do not modify the inner hub portion that is closest to the body. Since we do not reduce the width of the wheel, there is no need to trim this area to make it appear to have the same gap.
Pinewood Derby Speed Wheel Hub
Outer hub is modified. As per most packs rules, they allow this modification by addressing it. Or do not address it as a violation of rules to modify this area.
Increased outer hub diameter. We increase the diameter of the hub by 0.0015 inches. This decreases the outer axle hub rub/friction. By opening up this area, this modification allows the wheel to travel in a more true circular motion around the axle verses an elliptical rotation. Better, more true rotation of the wheel because the head of the axle will not rub while during rotation. Outer hub is retained. Per pack rules
Beveled outer hub. This modification decreases friction (red area in picture). We have chosen to have a wider point of contact between your axle and wheel. We feel the larger outer ring provides a more stable wheel travel when compared to just a rounded hub as most aftermarket wheels utilize. This helps the first time builders get the most speed and tuning out of their wheels. We also find that it eliminates most wheel wobble when installed on a 1.5-2 degree negative canter.
We also leave this as a 2 step hub. This allows for factory axle head depth. This also allows for proper wheel gap when using the axle tuning pliers. With a recessed rounded hub, you can no longer gap the wheel and adjust the axle with the pliers. You will have to tune your car, then push the axle in to reduce the wheel gap which can lead to undesired movement of the axle which will change your tuning work.
We also find that this type of profile allows for a larger area of graphite reserves (green area in picture). Why not store more lube for the upcoming races?