Derby Talk

ah8tk wrote:Here is the Maximum Velocity wheel go / no gauge. It uses 1.17" as the no go:

We're planning on using this same gauge this year. If the wheel fits into the 1.17 slot, then it's too small.

derbyrookie wrote:Our pack would like to tighten down on purchased wheels and someone has proposed the following rule be installed:

"Beveling, rounding, tapering, thinning, perforating, weight reduction or any other altering of the weight, size and shape of the wheel is PROHIBITED AND WILL NOT BE TOLERATED. (Removal of mold marks, sharp edges as well as polishing of hubs and bores is not considered altering as long as it does not change the weight, size and shape of the wheel). If the weight, size or shape of the wheel has been altered you can count on the car being disqualified. Car owners will be informed of the violations and given an opportunity to modify the car to meet these rules (i.e. attach new wheels from another kit). If they are unable to make those modifications to the tech team’s satisfaction in a reasonable amount of time, the car may still race but will be given a time of 5 seconds, thereby disqualifying it from the speed races."

1- Rule is WAY TOO LONG. Which Cub Scout will read this? Or understand it?
Anyone that does understand it, knows you're keeping them from improving their cars performance.

How 'bout using these two rules:

You must use official BSA Pinewood Derby bodies, wheels and axles. We do not allow pre-cut bodies re-sold by third parties. We also prohibit BSA Grand Prix Pinewood Derby wheels and axles that have been altered and re-sold by third parties.

Do not increase the wheel diameter, do not make the wheel bore any smaller.

Other than that, let the scouts learn what works and what doesn't. No one 'buys' the championship trophy because they have to work the BSA wheels into winning shape. Two other things we do:

Each den competes as a team. The den with the best overall result wins the Team Trophy. We will also award individual trophies.

The winning racer, not the parent, in each den must give a short speech on their best speed secrets upon presentation of their award. The committee decides the number of winners who must talk. Be prepared.

Not only do the best racers need to share their knowledge in order win the Big Trophy with their den, but the individual winners spill the beans on how they did better.

These rules have made a HUGE difference in our derbies. No crying, lots of close racing and kids LEARN while they HAVE FUN.

Mr. rpcarpe, you have made me smile. I'll bet you get some Tall stories when those little guys reveal their speed secrets. Do a lot of them use that white Teflon powder for their lube?

Oh Heck No! No white powder. We allow 'any lubricant that doesn't leak of foul the track'. Oil is gaining popularity 'round these parts.

When I interview the kids, they just look at me funny because I'm usually the one that taught them how to do it! So the 'interview' just refreshes what the kids all learned and surprises parents that didn't know about Rail Riding or Micro Mesh.

Here's how I'd approach the issue: 99% of all third party purchased wheels are mold matched. While there is at least one vendor that sells non-mold matched lathed wheels that are cut 4 at a time on a CNC lathe, they are in the minority, and actually she seems to have disappeared. So, I would worry less about diameter and more about matching mold numbers, as what are the chances of a car having 3 or 4 of the 4 wheels match? If a car has >= 3 wheels with mold numbers matching, we flag it for secondary inspection and dig deeper. This year, we reserve the right to disassemble any car suspected of cheating after the race is run.

And anecdotally, I built my car in 2 hours this last race because I hadn't planned on racing. I used the top half of the block from my son's car to build a 1/4" thick car (just ran it through my planer until it got that thin) and a 3.5 oz Tungsten canopy. Beyond flattening the wheel hubs and polishing the bores, which took a total of 5 minutes, I did no other wheel prep and spent my time on the axles. It was a 3 wheel rail rider with 1.5 degree bend on the front axle and 2.5 on the rears, but the wheels that were used were the four that came out of a kit. I got lucky and two matched, so I used them as the back wheels and used the worst for the non-touching wheel. But everything on my car came out of a BSA kit and was only worked on by me, and it was the fastest car at our Pack race. It was even faster than any of the cars that raced at our district race since my boys cars dominated district and my car was faster than theirs. It was also covered in black duct tape.

TXDerbyDad wrote: It was also covered in black duct tape.

Ah! The "speed secret!"

TXDerbyDad wrote:I would worry less about diameter and more about matching mold numbers, as what are the chances of a car having 3 or 4 of the 4 wheels match? If a car has >= 3 wheels with mold numbers matching, we flag it for secondary inspection....

I tried computing such probabilities once (you have to squint).

Note that Chinese-made Revell wheels tend to be mold matched. Being a "BSA licensed" product, not every unit would consider those "third party". Fortunately they indicate "Made in China" so they are easy to discriminate against USA-made mold-matched wheels.

TXDerbyDad wrote:This year, we reserve the right to disassemble any car suspected of cheating after the race is run.

"A Scout is trustworthy"?

FatSebastian wrote:

TXDerbyDad wrote:I would worry less about diameter and more about matching mold numbers, as what are the chances of a car having 3 or 4 of the 4 wheels match? If a car has >= 3 wheels with mold numbers matching, we flag it for secondary inspection....

I tried computing such probabilities once (you have to squint).

Note that Chinese-made Revell wheels tend to be mold matched. Being a "BSA licensed" product, not every unit would consider those "third party". Fortunately they indicate "Made in China" so they are easy to discriminate against USA-made mold-matched wheels.

TXDerbyDad wrote:This year, we reserve the right to disassemble any car suspected of cheating after the race is run.

"A Scout is trustworthy"?

Indeed, and yet people are imperfect and "make mistakes," which can sometimes mean buying a car off of ebay even though our rules specifically state we do not allow any third-party cars. Our last race resulted in the first cars ever being disqualified from our race for violating the rules. It was a hard thing to do to the boys involved, but the grandfather who purchased the cars knew better. We were able to track down the specific car's completed auction on ebay. Here are the photos of the car in question. The car that was raced is on the top of each photo, and the auction pics from ebay are on the bottom. We also had the Cub's statement that his grandfather hadn't purchased his car yet when we asked him how his car was coming 3 weeks before our race.






Notice the red paint overspray near the front wheel, the gouge in the slot near the top right wheel, and the green overspray on the top left corner.



And finally to show the complexity of the paint job and how unique it is, here is the original photo with the car raced with stickers, the car auction photos, and another car with similar style paint job from the same builder.


After showing these photos to a friend's wife who is a forensic scientist, she said she'd give it 99% probability that it's the same car, especially given the difficulty in recreating the paint job and the distinctive characteristics, most notably the ones on the bottom of the car. Also, the grandfather tried to say that he did the paint job with acrylic when it is in fact two part auto poly. He also stated that the car he ran was one he had built back in the 80s and was original down to the wheels, yet it had new generation wheels. The worst part for me was having a grown man who should have known better lie to my face. Ultimately, while he would not admit to buying the cars, he said he made them and his boys did nothing but put stickers on them; that last part being the only truthful thing he said during our conversation about the cars. We ended up disqualifying all three cars and moving the Webelos II and Bear den winners up a rung. I technically won the Old Timer's trophy, but I gave it to the Webelos II den leader who helped run the race with a note on the bottom telling him I thanked him for all his hard work and wished him and his son luck with our Troop since they were bridging up. I did this so no one would claim that I did it for the trophy. Yes, I wanted it and the bragging rights it afforded, but I wanted it clean and without drama. Since it was my event and I had final say in disqualifying the cars, I had to let the trophy go out of propriety's sake.

Unfortunately, due to this incident, the grandfather and his grandsons left the Pack after they were disqualified, though it's a small community and we still run into each other at things like sports and neighborhood activities. He still won't look me in the eye. They moved to another Pack, and I may have informed them of the issue because cheating, especially at my event when we explicitly stated no pre-built cars, makes me really angry.



Circling back to the probability of 4 mold matched wheels, you are right about the Revell wheels, but our rules state they must say "Made in USA." We event explicitly state that if they want to buy different wheels, they can get USA made wheels from one of the three local Scout stores, one of which is the BSA Museum in Irving which has its own track.

Stan Pope wrote:

TXDerbyDad wrote: It was also covered in black duct tape.

Ah! The "speed secret!"

Indeed! My boys went with silver metal tape, and lost precious hundreths of a second.

This gentleman needs to attend a seminar on "How to Cheat". If you're going to cheat you NEVER, NEVER put a fancy paint job on the car. That's an insult to the inspectors.

OK, kidding aside. Were these cars allowed to race and won their races? Did they dominate their races? Were they running 1.8 gram wheels? Were they rail riders where your rules might have made a rail rider illegal? Were your son's cars faster then these? I'm just curious why these particular cars would have been so fast.

I'm in charge of our District derby this year and we always model our pack rules straight from the District rules.

Our current district rules prohibit any "alterations" to the wheel, but allow "light sanding" for removing irregularities. I've always had an issue with what light sanding meant and how to determine if you've crossed the boundary from light sanding to medium or heavy sanding. In order to clarify this, I intend to modify the rules this year.

The intent of the rule change is to disambiguate the current rule and to put something in place that is testable. The other intent is to keep people from having to purchase expensive light weight wheels in order to be competitive. Here is the updated rule (updated parts in red font)

2. No alteration, narrowing, lathe cutting, or re-shaping of wheels (inside or outside) is allowed. Light sanding of the wheel treads to remove irregularities is permissible, but must be done with great care to avoid going below minimum wheel diameter specifications or minimum wheel weight specifications outlined below.
3. No alteration, narrowing, lathe cutting or reshaping of wheel hubs is permitted. This includes rounding or ‘coning’ of the hub face that meets the car body. Light sanding of the hub face to smooth the surface is permissible, but must be done with great care to avoid going below minimum wheel weight specifications outlined below.
4. The minimum outside diameter of all wheels, as measured by an official “go / no-go” gauge during inspection is 1.180 inches. If you leave the wheel alone, it will meet this specification.
5. The minimum wheel width of all wheels, as measured by an official “go / no-go” gauge during inspection is 0.360 inches. If you leave the wheel alone, it will meet this specification.
6. The minimum weight of each wheel, which may be measured after racing at the discretion of the racing officials is 2.6 grams. If you leave the wheel alone, it will meet this specification.

That last rule I wouldn't intend to enforce unless we found a wheel that was suspect during the "no-go" gauge test.

Other than bore and hub prep, I don't think the new (post 2009) wheels need much work done on them to be competitive anyway.

One other thing. I know Maximum V sells mold matched wheels that are not machined in any way. I've got a supply of those wheels we've used, so I don't think mold matching is a high percentage indicator of lightened/machined wheels.

Birddog

birddog wrote:I'm in charge of our District derby this year and we always model our pack rules straight from the District rules. Our current district rules prohibit any "alterations" to the wheel, but allow "light sanding" for removing irregularities.

If you are in charge of your District derby, do you have the authority or sufficient influence to remove the allowance for "light sanding" of the tread? IMO such rules were intended to address sprue marks on the treads, but the post-2009 wheels lack such marks.

I do have the authority to remove the allowance for light sanding, but when I mentioned that change to the past District PWD chairman, he felt there would be push back in removing things that were allowed in the past.

Based on that, I felt that I would keep the light sanding, but put measurable restrictions around it.

Personally, I think attempting to sand the tread on these new wheels can likely cause more harm than do good, but if folks want to do it, I just want to give them measurable standards for how much is allowed (which is very little).

Birddog

birddog wrote:Light sanding of the wheel treads to remove irregularities is permissible, but must be done with great care to avoid going below minimum wheel diameter specifications or minimum wheel weight specifications outlined below

So, If one were to lightly sand wheels with reckless abandon and still meet diameter specifications would that result in disqualification? I think the measurable part of the rule is the diameter spec, not how one arrives at it.

True, the measurable part is the part we care about, not how you go about it. Just wanted to be cautionary as I personally think any sanding of wheels has the potential to cause more harm than do good.

Birddog