Mold numbers and used/last year's wheels

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itgl72
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Mold numbers and used/last year's wheels

Post by itgl72 » Fri Jan 17, 2014 12:20 pm

I've got about 4 sets of stock BSA wheels here. Two extra tubes I bought at the BSA store, and the sets that came with the block kit at the den meeting.

So, from what Ive read in the forum here, its best to try to match wheels with the same mold number inside. My questions.

What happens if I do not have enough to make 4 exact sets? Is it better to match per axle? For example wheels up front are mold #3 while the back is mold #16 or does any of that really matter?

ALSO, I have several wheels from last year I can search for mold numbers on, even the car that raced has used wheels, do used wheels make a difference at all?



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Re: Mold numbers and used/last year's wheels

Post by Rukkian » Fri Jan 17, 2014 12:31 pm

I am by no means an expert, but from what I understand, the molds do not make as much of a difference on newer wheels. Mold matching was much more critical on the old (pre - 2009) wheels since certain molds typically made much better wheels. Mold matching is less about matching, then it is about getting good wheels.

On most setups, the back wheels need to be very good, since they will hold most of the weight, and they should also be as close to identical as you can get. If you have a 3 wheeler RR, then put any bad wheel there, and put the next best wheel in the dfw position.

As for used wheels, it is usually not recommended, as they may be pretty tore up depending on lube, amount of runs, and how they were stored. If the car sat on it for a year, you can get flat spots to some extent.



itgl72
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Re: Mold numbers and used/last year's wheels

Post by itgl72 » Fri Jan 17, 2014 12:38 pm

What I did last year with my son was, eyeballing it really. We worked on the axels with just a craftsman drill strapped down to a step stool because we dont have a work bench in our garage. (Keep meaning to get to that) and we took a bunch of axels and just worked them. We then took each axel, and each wheel (we had a few sets) and spun them on axels. The wheel/axel combos that seemed, to our eye, to look the smoothest, were the ones we put on the car. It came in 2nd with the tigers, and 9th out of 52 at district, so we might have guessed on something right.



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Re: Mold numbers and used/last year's wheels

Post by Curse You Red Baron! » Fri Jan 17, 2014 3:54 pm

Last year we ignored the mold numbers and went for trying to find similar wheels. A lot of wheels were out of round, and we used a home-made tester that someone had posted on Derby Talk (I think FS?) ... allows your scout to turn the wheel and determine how much variance there is from the hub surface to the wheel surface. I was really surprised how many wheels were really bad. When we had a batch of relatively good wheels, we checked wheel diameter and chucked a few more outliers - my scout prepped the best remaining wheels - they were amazingly quiet! Convinced me that the effort to build the tester was worth it. My Scout won his pack and district races, never lost a single race. I'm sure more can be done (measure hub diameter, axle diameter, etc) but we had all different molds mixed in, never worried about it.



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Re: Mold numbers and used/last year's wheels

Post by Topspin.D » Fri Jan 17, 2014 4:53 pm

You really should test each wheel for roundness. Sporty put together a long post about the wheel molding process and possibility of wheels coming from the same mold number but different spots on the mold not being the same. I like to mold match anyway because of the consistency around bore size that it brings.

If you're going to work the wheels with a lathe or hand lathe concentrate on finding wheels that are close to round with the smallest bore sizes (again mold number doesn't matter).

If you don't have 4 matched or "good" wheels put the best 3 in the rear and DFW. Your best 2 should be at the rear. 4th wheel (if raised) doesn't matter. Many of us look for 4 good wheels and fully prepare them so that we've got a spare wheel ready if there's an issue with the others.



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Re: Mold numbers and used/last year's wheels

Post by FatSebastian » Fri Jan 17, 2014 4:56 pm

Topspin.D wrote:You really should test each wheel for roundness. Sporty put together a long post about the wheel molding process...
Curse You Red Baron! wrote:Convinced me that the effort to build the tester was worth it.
Plans are here, or see p. 100 of Troy Thorne's Building the Fastest Pinewood Derby Car for more professional-looking instructions. Personally, we didn't think it was much effort to build, at least relative to a lot of other things we do to build a competitive car.



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Re: Mold numbers and used/last year's wheels

Post by chobo » Sun Jan 19, 2014 8:10 pm

The numbers in wheels indicate which cavity it came out of in the mold. It's all the same mold, but depending how the press was set up can make a world of difference in how the parts come out looking. One run of wheels may look different than the next and it can even change during the run; it depends on how well they pay attention (quality). As a previous poster stated, disregard the cavity number and just look for a good wheel.


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Re: Mold numbers and used/last year's wheels

Post by rcmoeur » Tue Nov 24, 2015 10:56 pm

I looked at several US wheel sets (from car kits and wheel kits) I purchased recently from the Scout Store. Two observations:

The wheels for sale in this year's kits and wheel sets (black or colored) seem to have a much rougher and "bubbly" texture on the inside of the wheel (near the "MADE IN USA" and sprue marks), on all mold cavity numbers. The inside lettering also seems less well-defined than previous years' wheels.
The red wheels have a notably different (more saturated) color, implying different materials or suppliers. The blue wheels seemed to have some variance, but not as noticeable. The orange and yellow seem unchanged.



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Re: Mold numbers and used/last year's wheels

Post by Vitamin K » Wed Nov 25, 2015 10:43 am

I don't really pay attention to mold numbers anymore. We just use the Fat Sebastian wheel gauge and pick the best wheels from our batch.



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Re: Mold numbers and used/last year's wheels

Post by knotthed » Wed Nov 25, 2015 12:58 pm

itgl72 wrote:I've got about 4 sets of stock BSA wheels here. Two extra tubes I bought at the BSA store, and the sets that came with the block kit at the den meeting.

So, from what Ive read in the forum here, its best to try to match wheels with the same mold number inside. My questions.

What happens if I do not have enough to make 4 exact sets? Is it better to match per axle? For example wheels up front are mold #3 while the back is mold #16 or does any of that really matter?

ALSO, I have several wheels from last year I can search for mold numbers on, even the car that raced has used wheels, do used wheels make a difference at all?


If there was lot # traceability from the manufacturer, this might have a chance at working, but since there isn't - throw the mold # idea out the window. I remember our first year, running around to multiple stores, trying to find tubes with the same numbers in them - what a waste of time.

The other reason to throw the mold numbers out the window, is because your local inspector might accuse you of buying modified wheels because the numbers match, as that is how some suppliers sell their wheels "mold matched".

I built a FS wheel gage, but was not satisfied with it due to the ease of pin movement and other stuff, so I set about to build a gage to check runout. I used it for a year and then decided to tweak the design and have some made.

Being able to change the pin size was a mandatory requirement for me.

They are available thru Derby Evolution and can be seen here; http://www.derbyevolution.com/Wheel-Run ... t-Gage.htm

Also, here is a YouTube video showing a demo; https://youtu.be/S4dpf8kmGqo



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Re: Mold numbers and used/last year's wheels

Post by FatSebastian » Mon Nov 30, 2015 7:14 pm

knotthed wrote:I set about to build a gage to check runout. [...] They are available thru Derby Evolution and can be seen here
That's cool.

It's nice that there is a commercially-made option available again. Years ago, there used to be a commercial wheel concentricity gauge offered through some vendors, but it was not nearly as nice as your design. The retail price approached $50, and vendors stopped carrying it due to poor sales.

:goodluck:



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Re: Mold numbers and used/last year's wheels

Post by Derby Evolution » Thu Dec 03, 2015 5:12 pm

FatSebastian wrote:
It's nice that there is a commercially-made option available again. Years ago, there used to be a commercial wheel concentricity gauge offered through some vendors, but it was not nearly as nice as your design. The retail price approached $50, and vendors stopped carrying it due to poor sales.

:goodluck:
I was one of the vendors that carried the other style of gauge. At the time the gauge was a great tool. We did not stop selling it do to poor sales. The manufacturer stopped producing them is why we stopping selling them. The current gauge is a amazing tool and I believe that each scout pack should own one. Think about it, they invest a lot of money into a nice track, software, and a computer to run the race. There are very few packs that invest in high quality tools that will last forever, that help the boys measure and check the quality of the items they are using in the construction of the cars.



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Re: Mold numbers and used/last year's wheels

Post by FatSebastian » Fri Dec 04, 2015 2:30 pm

Derby Evolution wrote:We did not stop selling it do to poor sales. The manufacturer stopped producing them is why we stopping selling them.
Thanks for the added clarification. I was told that the manufacturer stopped production because of low retail demand. Regardless, the new commercial tool is definitely better. :thumbup:



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Re: Mold numbers and used/last year's wheels

Post by Speedster » Fri Dec 04, 2015 3:13 pm

There are 16 mold numbers. The vendors have chosen 5 of the molds to be premium molds. They are 2, 3, 6, 8, 15. From the 1st Post it might be better to move the 3,s to the rear. You might choose to buy a set of one of the premium molds and test it on knotthed's gage, weigh it, spin it on the wheel balancer and see how it compares to other wheels you might have. Keep track of all your tests and pick the best 3 if you are running a 3 wheeler. Some wheels will definitely be more round than others. The gage and premium wheels can be purchased from Derby Evolution. I have a lot of fun giving my scouts 8 wheels and having them find the 4 that are perfectly round. They seem to have a lot of Fun doing that.



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