New BSA Wheels - More Specifications by Mold Type

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FatSebastian
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New BSA Wheels - More Specifications by Mold Type

Post by FatSebastian »

Below are some wheel data collected from a dozen sets of four wheels. Each wheel was given a unique "sample" number for ID purposes. The runout (R.O.) was measured with a dial indicator and rounded to the nearest 0.5 and reported in thousands of an inch. Bore diameters were approximately measured with plus-size plug gauges that were gently used as “feeler” gauges, and are reported in inches.

While the sample isn’t terribly large, the results seemed consistent with MaxV’s analysis of better c.2009 mold numbers and the experiences of others. Here were our impressions:

1) #2 seemed to be the consistently best mold for us in terms of roundness / runout. #8, #3 seemed next best, while #12, #15 were not far behind.

2) The outer hub bore is consistently narrower than the inner hub bore by ~0.0005” (the precision of the gages used). Not much variation was observed across the different molds.

3) The edge of the tread face toward the outside tends to be slightly rounder than the inner tread face. This may explain why some racers are now turning their wheels inside out (running negative camber)?

4) A few of the seemingly better molds (e.g., #3, #8) seemed more prone to having an obviously visible recess in the center of the bore, and should be watched for.

Hopefully this information is not coming so late in the season so as not to be useful to someone.

Sample, Mold #, R.O.(outer), R.O.(inner), Inner Hub, Outer Hub
16, 2, 0.5, 0.5, 0.0960, 0.0955
25, 2, 0.5, 1.0, 0.0965, 0.0960
28, 2, 0.5, 1.5, 0.0965, 0.0960
43, 2, 0.5, 1.5, 0.0965, 0.0960
22, 3, 1.0, 1.5, 0.0970, 0.0965
11, 8, 1.5, 1.0, 0.0970, 0.0970
48, 3, 1.5, 1.5, 0.0970, 0.0965
33, 15, 1.5, 2.0, 0.0970, 0.0965
1, 3, 2.0, 2.0, 0.0970, 0.0965
7, 8, 2.0, 2.0, 0.0970, 0.0965
45, 12, 2.0, 2.0, 0.0965, 0.0960
2, 15, 2.0, 2.0, 0.0970, 0.0965
13, 15, 2.0, 2.0, 0.0970, 0.0965
35, 15, 2.0, 2.0, 0.0970, 0.0965
44, 12, 2.0, 2.5, 0.0970, 0.0965
36, 12, 2.0, 3.0, 0.0965, 0.0965
38, 8, 2.5, 2.0, 0.0970, 0.0965
12, 3, 3.0, 3.0, 0.0965, 0.0965
18, 7, 3.0, 5.0, 0.0970, 0.0965
42, 16, 3.5, 3.5, 0.0970, 0.0965
34, 16, 3.5, 4.0, 0.0970, 0.0965
47, 7, 3.5, 4.5, 0.0970, 0.0965
9, 7, 3.5, 5.0, 0.0970, 0.0965
6, 7, 3.5, 6.0, 0.0965, 0.0960
10, 7, 4.0, 5.0, 0.0970, 0.0965
5, 10, 4.0, 5.0, 0.0970, 0.0965
32, 10, 4.0, 5.5, 0.0970, 0.0965
14, 7, 4.0, 7.0, 0.0965, 0.0965
31, 1, 4.5, 4.5, 0.0965, 0.0965
40, 4, 4.5, 5.5, 0.0965, 0.0960
29, 10, 4.5, 5.5, 0.0970, 0.0965
39, 13, 4.5, 6.5, 0.0965, 0.0965
27, 1, 5.0, 5.0, 0.0965, 0.0965
41, 1, 5.0, 5.0, 0.0965, 0.0965
37, 4, 5.0, 5.0, 0.0965, 0.0960
17, 11, 5.0, 5.5, 0.0965, 0.0960
26, 1, 5.0, 6.0, 0.0965, 0.0965
30, 1, 5.0, 6.0, 0.0965, 0.0965
8, 4, 5.0, 6.0, 0.0965, 0.0960
15, 9, 5.0, 6.5, 0.0960, 0.0955
46, 9, 5.0, 6.5, 0.0960, 0.0955
19, 6, 5.0, 7.0, 0.0965, 0.0965
20, 5, 5.0, 7.5, 0.0970, 0.0965
4, 6, 5.5, 7.0, 0.0965, 0.0960
21, 11, 6.0, 6.5, 0.0965, 0.0960
23, 11, 6.0, 7.0, 0.0965, 0.0960
24, 14, 6.0, 9.0, 0.0965, 0.0965
3, 6, 7.0, 5.0, 0.0960, 0.0955
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murphken
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Re: New BSA Wheels - More Specifications by Mold Type

Post by murphken »

Good stuff! :D I had one of my Bears come over yesterday to do some more work on his car. I am a den leader for two dens (wolf and bear). He has such a passion for this pinewood derby stuff! He had only one - #2 wheel in his box. I gave him another to put on the back of the car.

Did you use a microscope to see the recess? It looks like a shadow in our microscope. If we ream to .098 and clean-up with the Sporty polish technique, I wonder if it will be eliminated or reduced? Our pack race is not till February 20th and district is the next week after. I just might have to order reamer and play a little with a marginal set of wheels. Another thing my cub and I can play with!

We have a set of Derby Worx wheels that have apparently been reamed. They are all tore-up in the smaller bore area of the wheel. We are not using these wheels on our PWD car so we did not do anything with them. We just bought them as a reference. I would sincerely doubt if this bore damage could be cleaned-up with the traditional pipe cleaner and polish. Maybe I am wrong... Sporty's technique (0.50" rod with micromesh) would certainly shine them up!

On the other front, What is the issue if there is a slight recess in the middle of the bore? Does centrifugal force move all the graphite into this area? May this recess make the wheel what to wander in and out on the axle? Any thoughts? As an engineer, I love this forum! :idea:
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Re: New BSA Wheels - More Specifications by Mold Type

Post by hwsjr »

I can add a couple of observations from some personal experience I picked up yesterday. Grubartez was nice enough to let me and my son run two cars we have built for this year on his track. Each car ended up with about 7 or 8 runs. I just pulled a wheel from the slower of the two and inspected the wheel bore. Graphite did not appear to collect in the recess. In fact there appeared to be more graphite around the outer edge of the bore near the axle head than anywhere else inside the bore. The rest of the bore had a nice slick silvery look.

The other car ran a set of all #8's in the new wheels. I did not pull any of the wheels because that car ran so smooth, consistent and fast. We don't have a track, so I don't want to change the alignment at all before our derby. It consistently ran between 2.968 and 2.972 in its runs on Grubartez's 42 foot Best Track. So if what you are seeing with the bores of #8's is a problem, it did not appear to be one on those few runs.

Some additional info about the #8's we are running. We have removed the step on them with the pro hub shaver. We have polished the bores with Plastx and Micro-gloss. That is the extent of what we have done to the wheels. We did not work on the tread at all. Our rules prohibit machining, so I feared we would make them worse instead of better.
Last edited by hwsjr on Sun Jan 24, 2010 9:24 pm, edited 1 time in total.
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FatSebastian
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Re: New BSA Wheels - More Specifications by Mold Type

Post by FatSebastian »

murphken wrote:Did you use a microscope to see the recess? It looks like a shadow in our microscope.
We hold the bore against an evenly lit background light source (a high-res LCD monitor) and the trough shows up clearly as an absence of reflection (shadow, as you say).
murphken wrote:What is the issue if there is a slight recess in the middle of the bore?
I personally don't know if it causes an issue - just a precautionary note to anyone looking at some of the better molds. Based on our limited experience so far with the new wheels, I see no reason to not use wheels with noticeable bore recess. This thread suggests that if you are using sufficiently canted axles, the middle of the bore may not make contact with the axle anyway. :thinking:
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Re: New BSA Wheels - More Specifications by Mold Type

Post by Grubartez »

hwsjr - that was a very fast car you guys had. It was very smooth and fast. No wiggles, just hooked up and screaming down the track. The only thing left you guys could try would be adjusting the rear axles. Most of the time, I can find a little more speed by rotating the rear axles around. You could most likely get that car running in the low 60's. I'm glad I could help you out with a little track time.
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Re: New BSA Wheels - More Specifications by Mold Type

Post by hwsjr »

Of course, fast is relative. We got to see the fastest cars I've ever seen in person when you ran a few of yours, but I was pleasantly surprised at the times on the one we did.

We really appreciated your kindness. It's nice to see one of our creations actually run down the track prior to race day!
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Re: New BSA Wheels - More Specifications by Mold Type

Post by TOU »

So the question that comes to mind...what do we do with all the other wheels that we get accumulating these preferred wheels?
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Re: New BSA Wheels - More Specifications by Mold Type

Post by Kenny »

FS~

Thanks for measuring and posting your sample. It is helpful to have different folks perform these checks periodically over time since molds age and get replaced over time. Your numbers definitely contribute to nice baseline snapshot.

K
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Re: New BSA Wheels - More Specifications by Mold Type

Post by FatSebastian »

TOU wrote:what do we do with all the other wheels that we get accumulating these preferred wheels?
IMO, unmodified the worst of the new-style wheels are probably better than the best of the old-style wheels, so things are relative; however...

You might experiment with them; for example, turn them into razor wheels. We plan to do some friction bench tests and try sporty's bore prep with some of our less-preferred molds. We also practiced our balancing technique with our less-preferred molds first.

If your rules allow, you could shave them on a lathe.

If you can raise one of the front wheels, then you might use a less-preferred mold in that spot.

If you have a car that you are retiring, or a show car, you might use the less-preferred molds on it.

Make a big-rig out of them?
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Re: New BSA Wheels - More Specifications by Mold Type

Post by Davhamm »

hwsjr wrote:...
The other car ran a set of all #8's in the new wheels. I did not pull any of the wheels because that car ran so smooth, consistent and fast. We don't have a track, so I don't want to change the alignment at all before our derby. It consistently ran between 2.968 and 2.972 in its runs on Grubartez's 42 foot Best Track. So if what you are seeing with the bores of #8's is a problem, it did not appear to be one on those few runs.

Some additional info about the #8's we are running. We have removed the step on them with the pro hub shaver. We have polished the bores with Plastx and Micro-gloss. That is the extent of what we have done to the wheels. We did not work on the tread at all. Our rules prohibit machining, so I feared we would make them worse instead of better.
Well With 8's in the rear 15 on the front my daughter got a 2.9528 but I think its a 35 foot best track. Nothing done to the wheels except micropolish on the hubs. Heres the video:


https://youtu.be/
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