Allow Lightened wheels?

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pwrd by tungsten
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Allow Lightened wheels?

Post by pwrd by tungsten » Mon May 17, 2010 11:50 pm

What is everyones thoughts on allowing lightened wheels?


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Re: Allow Lightened wheels?

Post by Stan Pope » Tue May 18, 2010 9:56 am

I'm against allowing severly lightened wheels.

Severly lightened wheels (the 1 gram variety) are expensive to buy and difficult to make. If allowed, they would be necessary to be competitive. This increases the motivation to buy. If there were inexpensive tools which would a youngster could use to accomplish such lightening with reasonable effort and difficulty, then I think that I would have fewer issues.

The closest I've read re "inexpensive tools" is "sandpaper wrapped on a socket". I have not tried the technique, and I don't know if the results have sufficient quality and consistency to offset my concerns.

There are lots of ways to drill quality axle holes, but few ways to lighten wheels. If the tooling necessary to work the wheels were unique to the extent of being "single source", i.e. a patented tool, then I still have an issue, even if the tool were as inexpensive as a $12 Werby Dorx tool.

I can not justify telling folks that they need to buy finished wheel or some specific patented tool in order to be competitive.


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Re: Allow Lightened wheels?

Post by gpraceman » Tue May 18, 2010 10:21 am

I also agree about not allowing the ultra light wheels. I think the original lettering inside and outside of the sidewalls should be retained and that the ring of nubs near the tread should still be visible. That leaves wheel width, tread thickness and the inner hub diameter to worry about.

If using the newer BSA wheels, I wouldn't worry so much about the inner hub diameter, since they are already pretty slim.

For wheel width, you can do a visual comparison with an unworked wheel to see if there is a noticeable reduction. For the "lawyer" types, you might want to specify a minimum width and be prepared with some calipers to measure it.

For tread thickness, again you can do a visual comparison with an unworked wheel. To be more enforceable, you would have to specify a minimum tread thickness.

On taking wheel measurements, I do not propose to do that for every car checking in, as that would slow things down significantly. Just pull out the calipers when there is a noticeable variance from an unworked wheel.

While at least one district I know weighs wheels, I think that might be carrying things a bit too far.


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Re: Allow Lightened wheels?

Post by FatSebastian » Tue May 18, 2010 11:40 am

pwrd by tungsten wrote:What is everyones thoughts on allowing lightened wheels?
IMO this is a much tougher question that the one about disallowing extended wheelbase.

I would tend to agree with others' comments about disallowing "severely" lightened wheels; however, a concern I might raise is how does one practically define and inspect "severely"? Specifically, what about mildly lightened wheels, say, a 2009 wheel that has been balanced by removing minute amounts of mass (less than would be detectable on an affordable pocket scale, say, 0.1 g)? That doesn't seem like an unreasonable modification, because one is actually trying to correct anomalous manufacturing variability rather than alter the fundamental design characteristics of the wheels (unlike, say, tread alterations or significantly decreasing mass moment of inertia). Same argument might be made for bore reaming / polishing - technically a slight amount of mass is removed whenever reaming / polishing occurs to correct manufacturing issues.



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Re: Allow Lightened wheels?

Post by Darin McGrew » Tue May 18, 2010 1:14 pm

Our rules allow removing manufacturing irregularities from the wheels, but do not allow reshaping the wheel. The distinction in my mind is the difference between making it the best Shape N Race wheel it can be, and making the best wheel you can make using the Shape N Race wheel as the raw material.

Lightening the wheels would be considered reshaping the wheels. Removing small amounts of material to balance or true the wheel would be considered removing manufacturing irregularities.



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Re: Allow Lightened wheels?

Post by FatSebastian » Tue May 18, 2010 3:01 pm

Darin McGrew wrote:Lightening the wheels would be considered reshaping the wheels.
FWIW, the rules sets that we have competed under that forbade "reshaping the wheels" were usually interpreted as alteration of the tread surface, such that "no shaving" was added for clarity (to further suggest lightening the wheels via lathing).
Darin McGrew wrote:Removing small amounts of material to balance or true the wheel would be considered removing manufacturing irregularities.
It seems the distinction may be whether the mass is removed discretely (incrementally) and in small amounts, versus a relatively large amount in a continuous and symmetrical fashion. If so, what would be a preferred way to express this idea simply in rule form? :thinking:



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Re: Allow Lightened wheels?

Post by Mr. Slick » Tue May 18, 2010 3:27 pm

Until your favorite tool vendor comes out with a $12.95(affordable by most) tool that allows 95% of kids(almost every YOUTH) to perform the task, don't allow it.

As I once heard, "Using lightened wheels is an attempt to buy your way to the trophies." and that is not in any of the purposes of that I have read for these races.


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Re: Allow Lightened wheels?

Post by FatSebastian » Tue May 18, 2010 6:04 pm

Mr. Slick wrote:Until your favorite tool vendor comes out with a $12.95(affordable by most) tool that allows 95% of kids(almost every YOUTH) to perform the task, don't allow it.
:thinking: If the BSA began marketing officially licensed Speed Wheels (ultra-light and/or razor) for, say, $12.95 / set, would it then be reasonable to allow?

(Although we would all love to such a tool priced at $12.95, IMO that seems much too low. At that price point one cannot even buy enough tungsten or lead-substitute for a single car, whereas a wheel-lightening tool not unlike the Derby-Worx Pro Wheel Shaver XT could be used over and over again during a racing career, with the prorated cost per car costing less than competitive ultra-dense ballasts.)
Last edited by FatSebastian on Wed May 19, 2010 10:23 am, edited 1 time in total.



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Re: Allow Lightened wheels?

Post by pwrd by tungsten » Tue May 18, 2010 8:42 pm

I like having non-lightened wheels as a rule. The trick will be in enforcing it and allowing everyone to race and enjoy the day. I really want everyone to be able to race.


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Re: Allow Lightened wheels?

Post by FatSebastian » Tue May 18, 2010 8:45 pm

pwrd by tungsten wrote:I like having non-lightened wheels as a rule.
Out of curiosity, may we ask how the rule is / will be / should be worded?



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Re: Allow Lightened wheels?

Post by pwrd by tungsten » Tue May 18, 2010 11:23 pm

That is a trick. It is almost impossible to write a good rule. Thoughts apreciated.

Some key factors are the writting on the outside and inside of the wheel must show. But that allows some store bought semi-lightened wheels to exist...


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Re: Allow Lightened wheels?

Post by Stan Pope » Wed May 19, 2010 1:00 am

pwrd by tungsten wrote:That is a trick. It is almost impossible to write a good rule. Thoughts apreciated.

Some key factors are the writting on the outside and inside of the wheel must show. But that allows some store bought semi-lightened wheels to exist...
I approached it by specifying which surfaces could be "worked" and geometry limitations on that work, using original wheel features as reference but no "precision measurements". (An interesting end result was that balancing by changing the interior tread surface could only be done by adding weight, e.g. glue spot, rather than removing weight, i.e. divots of plastic. The reasoning was that how many divots would be needed to achieve balance was not a predictable number. However, few would keep adding weight until "perfect balance" was achieved.)


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Re: Allow Lightened wheels?

Post by pwrd by tungsten » Wed May 19, 2010 1:05 am

I like that aproach. That kicks out some of the semi-lightened wheels as well... :D


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Re: Allow Lightened wheels?

Post by Darin McGrew » Wed May 19, 2010 7:09 am

The text of our current rule is:
The original wheels and axles cannot be reshaped, although manufacturing irregularities (e.g., sprue, flash) can be removed.
It helps that the wheels and axles in our kits are very good, and don't need to be reshaped before use. We encourage everyone to polish the axles. A few will true the wheels on a mandrel, which requires removing very little material from our wheels. But that's all anyone can really do to improve them, without reshaping them in some way.



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Re: Allow Lightened wheels?

Post by Duane » Wed May 19, 2010 8:40 am

It seems to me that a wheel's weight can be accurately measured at check-in, without removing it from the car.
When the car is pointed axle-head down, the wheel will freely move up and down on the axle shaft by 1/16" or 1/32" or so.
Put a wheel-shaped ring on the scale. (Eg a spare wheel.) Zero out the scale. Push the car's wheel down on the ring, just enough that the wheel lifts off from the axle nail head, but without pressing the body of the car down on the wheel too. The scale will then show the weight of the suspended wheel. You don't have to be able to see what's going on with the clearances, just go by the indicated weight. It's either zero, or way more than the weight of a wheel, or the wheel weight.

Problem is, my kitchen food scale doesn't read out in units smaller than whole grams, and that is too coarse for measuring a 3-gram weight.

I use a variation of this technique for measuring the weight distribution and com placement of a completed car. Put the front wheels of the car on the scale. Hold the back end of the car off the side of the scale, by the back axles, so the front is free to flop. Raise or lower the back end until the car is sitting approximately level. The scale is then reading the weight of the car that is normally pressing on its front wheels during use. This leads to better decisions than arbitrary notions of where the com should go. (Underloading the front wheels will lead to big steering problems, for negligible gains in total potential energy.)



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