New BSA Wheel and Axle??

[Go Bubba Go]

Maybe there are not always new axles with the new wheels ?

I think that is a correct statement, from other feedback that I have heard.

It seems that are using a "Cracker Jack" distribution strategy i.e. "A surprise in every box".

Just thought I'd throw that out there for us old guys...

Bubba

[hwsjr]

Does anyone know if the new wheels will be in kits (some or all) or just in the packs where you are buying just wheels and axles?

[Randy and Son]

Not being able to acquire a set of the new wheels hasn't stopped me from a bit of [speculating] about them. Here goes.

With the changes to improve the new wheel such as coned hub and reduced mass, why would the tiered (or stepped down) bore opening on the outside face of the wheel be an advantage? Is it possible that it is an attempt to minimize the effect of not removing the flashing under the axles heads? Someone failing to remove the flashing might pay less of a penalty if it can't touch the wheel. And usually the worst of the flashing is nearer to the axle shaft. Just a thought.

The new wheels are reported to weigh about 2.6 grams, if I recall. They appear to have less hub mass than the old wheels, but does that really make them better than the old wheels? Well, yes, overall they will be better than the old 3.6g wheels, but I remember a thread on DerbyTalk that mentions reducing wheel weight by removing hub mass is not necessarily the best place to remove mass.

This is the thread: Minor wheel weight reduction

And specifically from that thread, this quote ...

... observed that hub mass, having a small radius contributes little to wheel angular inertia, but has the beneficial effect of transferring mass off the body while retaining mass in the car. This is beneficial because friction between axle and wheel is computed based on the weight of the body (car weight less wheel weight).

So it would seem that a set of 2.6g "old" wheels could be better than 2.6g "new" wheels in at least one regard. (If hub mass is retained.) [/speculate]

Randy

[gpraceman]

With the changes to improve the new wheel such as coned hub and reduced mass, why would the tiered (or stepped down) bore opening on the outside face of the wheel be an advantage? Is it possible that it is an attempt to minimize the effect of not removing the flashing under the axles heads?

I tend to think it was a purely material savings concern that led to that stepped design. Less cost to BSA, meaning more profit.

Does anyone know if the new wheels will be in kits (some or all) or just in the packs where you are buying just wheels and axles?

I don't think there is anyone that knows just when they will start showing up in the kits. It is certainly hard to find anyone at BSA that knows much.

[quadad]

Good observation that the mass off the hub has less of an impact to angluar momentum (spin up and down effect). Its going to be an 'exercise left for the reader' though to figure out what the impact exactly is though since there is less mass all over, and appreciably in the tread wall. Here are some quick differences from one set of "old" yellow wheels to one set of "new" yellow wheels (average values for the four):

Outer Diameter New:1.185" Old: 1.191"
Tread Wall Thickness New: 0.067" Old: 0.095"
Inner Hub OD: New: 0.227" Old: 0.268"

No question that the dimensions appear to be better controlled on the new wheels though. They just seem like nicer parts.

Could still be getting worked up about nothin' , since we don't know what we will be racing with this Fall. "Parts are Parts" according to the Scout Shop.

[sporty]

I will go out and say that I really feel that the recessed bore is to less impact the imperfections from the burrs and die stamp marks on the axles.

So I feel that for those not doing axle work, will still do well with this new design.



I have been spending many hours lately testing and playing around and I feel these new wheels certainly are a better wheel.

More true and rounded, wheel bore much more consistant from one wheel mold number to the next.

One thing we sometimes forget to mention.

Say a pack of 40, all race. Only likely to see 10 racers due the prep work on the old wheels to match that of the new molded wheels.

Then maybe 20 them do the axle prep.

Still, many of the average parent/scout will not due the wheel work to the old wheels or have not in the past. So those average scout families are very likely to fair much better with the new wheels.

This is going to give them a better chance, a faster car with what the average scout family does with there cars.

Sporty

[sporty]

TEST DATA

K, I grabbed a older car, no thrills no spills. all 4 on the ground, 5oz. no cant / no rail rider.


data-

old stock wheels / prepped axles. Axles marked to ensure accuracy of future tests as follow:
(Noted: Manual start gate) "all tests no lube was used"

old stock wheels out of the container.

1- 2.792 (first run was the fastest)
2- 2.848
3- 2.980
4- 2.973
5- 3.001
6- 3.005

Old stock wheels prepped.

1-2.521
2-2.480 (fastest run)
3-2.492
4-2.497
5-2.503
6-2.497


new wheels (stock out of the container)

1-2.456
2-2.450 (fastest run)
3-2.477
4-2.476
5-2.479
6-2.484
~~~~~~~~Noted all those testes were with the same marked prepped axles.


Next two tests:

Used stock axles right out of container.

new wheels right out of container.


1-2.513 (first run was the fastest run)
2-2.517
3-2.533
4-2.520
5-2.537
6-2.526

old wheels right out of container.

1-2.727 (fastest run)
2-2.741
3-2.801
4-2.831
5-2.847
6-2.857


Conclusion:

with prepped axles. the fastest times even when comparing a old prepped wheel.

The new wheel in stock condition was faster !

Summary 1 fastest time=

Old stock wheels 2.792
old stock prepped 2.480
new stock wheel 2.450

Summary 2 Fasest time+

Stock axles used

new molded wheels 2.513

old stock wheels 2.727


final notes:

I did not prep a new set of the molded wheels for the testing, stock new out of box used.

I wanted to compare it against a prep wheel of old mold wheel and non prepped old mold wheel.

My testing is not perfect or rigged, i do have manual start gate and only lane 2 of the track was used. same lane for all testing.

but As I have seen with my testing the new molded wheel is far better in the scenerios we have had questions about.

recessed wheel bore on the new molded wheels, does provide a better performance when comparing to the old stock wheels, when using stock axles, non prepped.

We see also that the new mold wheel performs even better against the prepped old mold wheel.

Sporty

[Stan Pope]

Thanks for running tests. Interesting results. I think that the results were in line with expectation.

One of the attempts to control variance was "marking the axles", presumedly to assure that reinsertion with wheel change was invariant. We THINK that the axle orientation was not a factor in the time differences.

To demonstrate that the desired invariance was actually achieved, you should make two (or more) rounds of timings for each test case with wheel change(s) in between. Consistency of results between the two rounds for each case helps assure that the axle orientation was NOT a factor.

On the prep for old wheels, is it correct that no significant weight reduction occurred?

[sporty]

Axles were marked, to ensure same placement, axle gap was the same also. using axle gap tool.

The prepped wheels were 3.3 gram. not as fully prepped as some out there, but were still less than the stock wheels at 3.6 grams.

glad you asked, i did not think to post that info.

Sporty

[Stan Pope]

Axles were marked, to ensure same placement, axle gap was the same also. using axle gap tool.

Yes, that is what I understood. My experience is that small differences in axle orientation or insertion depth can make big differences in performance. The experimental procedure revision that I suggested demonstrates and quantifies the extent, if any, of such difference. The reader is left with a "warm, fuzzy feeling" about the quality of the results.

[Stan Pope]

Just for grins ... I wrote a Least Squares Multiple Regression program earlier this week ... fed your data in as follows:
X1: Run Number (1 through 6)
X2: Wheel model: 1=New, 2=old
X3: wheel prep: 1=Normal, 2=No prep
X4: axle prep: 1=Normal, 2=No prep
Y: Run elapsed time, seconds

The regression formula is spit out is
Y = 1.35 +0.016 X1 +0.37 X2 +0.388 X3 -0.0392 X4

To the extent that the formula is correct, it suggests that wheel model (old to new) is worth 0.37 seconds(0.37 X2) and that wheel prep gains about 0.39 seconds (0.388 X3 ). I kinda discount the suggestion that prepping the axles costs about 0.04 seconds (-0.0392 X4) because of the very low coefficient of correlation

The Coefficients of Correlation for Run Number and Axle prep are both very low, accounting for less than 2% of the variance in time. Wheel prep accounted for about 15% and Wheel Model accounted for abut 40%.

Given the low correlations, it is likely that the regression formula does not predict the time outcomes well. If I understand the statistics properly, it also suggests that nearly half of the variance (at least 43%) is not accounted for in a linear relationship to the data collected. That could be "noise" (i.e. random variations) or it could be "a real difference between runs and cases that we have not identified" (e.g. axle orientation) or it could be "a relationship exists, but it is not linear". Actually, all three are probably involved. (Or it could be a bug in the M.R. program. But I did validate the program with some good test data.)

The numbers were :
--- Regression Coefficients ---
B(0) = 1.35406833333334
B(1) = 0.0160400000000003
B(2) = 0.369583333333331
B(3) = 0.388208333333324
B(4) = -0.0392499999999956

--- Regression Formula ---
Y = 1.35 +0.016 X1 +0.37 X2 +0.388 X3 -0.0392 X4

--- Coefficients of Correlation ---
R(1) = 0.143 R-Squared(1) = 2.04%
R(2) = 0.6308 R-Squared(2) = 39.8%
R(3) = 0.3837 R-Squared(3) = 14.7%
R(4) = 0.07301 R-Squared(4) = 0.533%

[quadad]

Another quick observation on the new wheels (sorry not all at one time) ... I did quick spin test of the (8) new wheels. (5) of the (8) were excellent , (3) were good, none were really bad. While a small sample, this is MUCH better than the old wheels, where I would say less than 1 out of 8 are that good. I think that's part of what Sporty is seeing with the un-prepped wheels.

[Pinewood Daddy]

This is quite a tease!!!! When will they be in the scout shops??!!

I've got at least 100 of the old wheels that have been picked through the last 3 years. Mostly junk left. I had hope to not spend much on our son's last PWD but I guess we're going to have to by a few sets.

There's still 4 months until our Pack buys kits for the 2009 PWD. That gives them plenty of time to get the new wheels into the kits. Our BIGGEST PROBLEM is that we bought a case of cars last year to get the quantity discount thinking we'd buy another case this year and have enough left over to not have to buy them the following year. That means we have 15-20 of the old style kits! Some kids may end up with the old style wheels and some with the new and have a big advantage directly out of the box. What do we do with the old kits???

[Stan Pope]

This is quite a tease!!!! When will they be in the scout shops??!!
... What do we do with the old kits???

I think your committee needs to identify contingencies:
1. What to do if the kits on sale appear to be 100% new.
2. What to do if the kits on sale appear to be 100% old.
3. What to do if the kits on sale are mixed old and new.

Case 1 ... simply assign old kits for use in design-only constructions. It may take a year or three to dispose of the inventory. Some small percentage of folks make second design-only entries.
Case 2 ... disallow new wheels except for design-only constructions. Buying extra wheels gets more expensive, i.e. buy complete kits instead of wheels-only kits, but the cost is equal for all who choose that path.
Case 3 is the tough one!
Possibilities:
a. allow working old wheel tread thickness to equivalent of worked new wheel tread thickness.
b. hold present working standards for both types, and provide separate competition categories.
c. "stick your head in the sand" and pretend that there is no problem.
d. (other???)

Absent other possibilities, "a" appears to be the only workable alternative. It isn't easy: Rule writers need to measure the new wheels carefully to see what tread thickness can be achieved within the rules for working wheels. Specific rule needs to be written to cover the transition. Builders choosing to work the interior tread face need access to gages. Inspection staff needs to be able to gage tread thickness reliably and expeditiously.

[quadad]

Possibilities:
a. allow working old wheel tread thickness to equivalent of worked new wheel tread thickness.
b. hold present working standards for both types, and provide separate competition categories.
c. "stick your head in the sand" and pretend that there is no problem.
d. (other???)

Absent other possibilities, "a" appears to be the only workable alternative. It isn't easy: Rule writers need to measure the new wheels carefully to see what tread thickness can be achieved within the rules for working wheels. Specific rule needs to be written to cover the transition. Builders choosing to work the interior tread face need access to gages. Inspection staff needs to be able to gage tread thickness reliably and expeditiously.

Short of having each Council work with "all New" or "all Old" wheel designs (and a free exchange program to achieve this), I don't see any good options right now. I don't think the great majority of PWD car builders have the skill to modify the old mold wheels to be competive with the new ones. Why should it be their fault they received the old style ? ... Which brings me back to the free exchange program ...