Our 2019 Cars

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
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Vitamin K
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Our 2019 Cars

Post by Vitamin K »

Figured I'd share the details of our latest family builds here. We've left the BSA and our kids do American Heritage Girls and Trail Life now. It so happened that one of the TL Troops in the area runs a joint race for Trail Life and AHG, so our Troop participated.

They didn't restrict what kits we used, so we elected to go with Maximum Velocity over their default suggestion (Pinecar). Did a bulk buy for the Troop and then used two Troop meetings to offer some building help to the boys (bandsaw, scrollsaw, beltsander and axle polishing station).

Anyhow, here's the lineup for our family. From left to right, "Rrrrockit" was run by my six year old son, "Sharkinator" was made by my 12 year old son, "My Shot" by my 14 year old daughter and "Evil Potato" which was my car for the adult races.

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"My Shot" was weighted with tungsten because my daughter actually knew where her cubes from a previous year were. My 6 year old had left his car from last year at my parents' house, so we couldn't get the tungsten from that. My 12 year old didn't want to have to extract his cubes from an older car (lazy), and I couldn't find any more spare cubes. So aside from my daughter, we went with lead weights. For "Rrrockit" and for "Evil Potato" we did the "thin body with lead bars glued in" approach. Because "Sharkinator" changed course mid-stream and close to race day, we ended up cutting a wedge with inserted 3/8" cylinders.

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We drilled the bodies with the Clear Drill Jig that Micro makes. While I still have a special place in my heart for bent rears, I have to say that owning this thing makes getting good rear alignment stupid easy. And it's great because the kids can do it on their own. We use the recommendation of, after drilling the first rear axle hole, inserting a .089" pin gauge into the hole before drilling the other side.

We bought some extra wheels and used our FatSebastian runout gauge to select good ones. We didn't have to look far. I think the average amount of radial runout in the Max-V wheels was between 2-3 thousandths of an inch, and I found quite a few that were 1 or less. Was pretty impressed by that.

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Wheel bores were polished with a Tamiya swab chucked into a drill. Was out of Novus 2, so we used Plast-X instead. Seemed to work about the same.

We polished axles on my homemade polishing jig, which had at one time been parts for what I hoped would be an improved wheel shaver. That never panned out, but it did make an excellent tool to polish axles with! We polished with wet/dry sandpaper, starting at 1k and going progressively up to 3k. I was too lazy to find any strips of leather to use for Brasso or Mothers' for the final polish, so we just skipped that.

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Bent the DFW axles with a block of wood and a pair of pliers, using the Stan Pope method. I bent a test axle to the point where I could just barely fit it into a test wheel, and then we bent the rest of the axles to that point.

The rules said "Only dry graphite or silicone lubricants" (Booo!) so I took that to mean that pledge was okay. So after polishing, we sprayed the axles in Pledge, let them sit for about 15 minutes, then wiped them off with a paper towel that also had a bit of Pledge sprayed on it. I honestly have no idea if the Pledge helped, but it didn't seem to hurt us...

For the wheels, we burnished the bores and hubs with Maximum Velocity graphite. We used an old Pinecar straight axle that I polished up. For the outer hubs, we used a q-tip in a drill, and for the inner hub we used some graphite in a paper towel. I set up a shallow cardboard box with a layer of foam rubber in it for the kids to do their burnishing in. Did a pretty good job of containing the mess, though the cat did decide to curl up in the box later...

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When we put the axles into the wheel bores we lubed the interface with Hob-E-Lube graphite.

Set the drift of the cars to about 5-6" over 4' on Ye Olde Tuning Board.

"Rrrockit" took first in the 4-6 year old age group. "Sharkinator" and "My Shot" were 2nd and 1st in the 12-16 year old age group. "Rrrrockit" and "My Shot" moved on to the Grand Championships (I know, sucks when they only promote one car per class) and two 2nd and 1st respectively. I think having that tungsten really helped my daughter's car.

Oh, and I won the parents' race, and got a Starbucks gift card. Whoo!
Speedster
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Re: Our 2019 Cars

Post by Speedster »

Great looking cars. Reminds me of the Daytona 500.
I have a couple of questions.
What is Plast-X and where can it be purchased?

The nail? The nail comes with a shiny zinc coating. Can any amount of sanding or polishing actually make the nail more slippery? The wheel bore is polished, then 3 coats of Liquid Glass
( or some other wax) is applied, then 3 or more layers of graphite is applied and wheels finger spun, Does the plastic of the wheel ever touch the zinc coating of the nail? Do the wheels actually ride on the outside edges of the bores? I turn the axles around slowly like Doc Jobe suggests and apply that invisible coating of graphite. I suppose it can't hurt. I'm a firm believer that sanding or even polishing with a Dremel and Brasso does more damage then good. We do remove the casting marks under the head of the BSA nail. I'm used to getting hollered at but if
anyone is going to holler REALLY LOUD please email me. I know you mean well. There's no sense in getting anyone upset.
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Vitamin K
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Re: Our 2019 Cars

Post by Vitamin K »

Speedster wrote: Tue Feb 19, 2019 9:35 am Great looking cars. Reminds me of the Daytona 500.
I have a couple of questions.
What is Plast-X and where can it be purchased?

The nail? The nail comes with a shiny zinc coating. Can any amount of sanding or polishing actually make the nail more slippery? The wheel bore is polished, then 3 coats of Liquid Glass
( or some other wax) is applied, then 3 or more layers of graphite is applied and wheels finger spun, Does the plastic of the wheel ever touch the zinc coating of the nail? Do the wheels actually ride on the outside edges of the bores? I turn the axles around slowly like Doc Jobe suggests and apply that invisible coating of graphite. I suppose it can't hurt. I'm a firm believer that sanding or even polishing with a Dremel and Brasso does more damage then good. We do remove the casting marks under the head of the BSA nail. I'm used to getting hollered at but if
anyone is going to holler REALLY LOUD please email me. I know you mean well. There's no sense in getting anyone upset.
Plast-X is a plastic polish that Meguiars makes. You can get it at any auto parts store: https://www.meguiars.com/automotive/pro ... -oz-liquid. It's just a plastic polish (like Novus 2) that you'd use for stuff like headlights.

Regarding the axles, since we were using Maximum Velocity kits, we didn't have any flashing or crimp marks to deal with. Also, the axles aren't coated, to my knowledge. When we run BSA axles, we leave the crimp marks alone now, and just focus on removing the flashing under the head. We still polish to a mirror shine, though. I guess I have more faith in a shiny steel finish than a dull zinc finish. FWIW, the axle usually ends up coated with silicone anyhow (Pledge for graphite, Max-Pro for oil), so maybe that helps the CoF as well.
Speedster
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Re: Our 2019 Cars

Post by Speedster »

The MV axles have a zinc coating on them as do the BSA axles and they are quite shiny. If you take a strip of 3M's 3000 grit Trizact Performance sandpaper, wet sanding only, and hold it against a spinning nail, I agree, out of the light the sanded area looks more shiny. Hold the nail under a light and the reverse is true. Please don't ask me to explain that. My point of this is simply a search for the truth. It is directed to the poor team who starts out with 600 grit wet sandpaper and then sands up to 3000 grit, polishes with Brasso, and then like you said, buffs with leather. I then ask them what they did to the wheel and they say, "We put some graphite in the bore". If it can't be proven that sanding a BSA nail is a benefit, then stop doing it. If an
adult helper wants their scout to sand a nail a bit with 3000 grit, fine, the scout has experienced something. Time is very precious. Let's not waste it grinding away at a nail.
Thank You.
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whodathunkit
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Re: Our 2019 Cars

Post by whodathunkit »

Woo Wee! Look'en Good !!! VK kids!

VK,
Do you know if there is any benefit to treating the wheel bores with pledge as well for the graphite lubes ?
If it works good for axles why not the wheel bores also. (Just thought I'd ask if you have tried this .)
What type of automobile can be spelled the same forwards & backwards?
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Vitamin K
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Re: Our 2019 Cars

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whodathunkit wrote: Tue Feb 19, 2019 8:12 pm Woo Wee! Look'en Good !!! VK kids!

VK,
Do you know if there is any benefit to treating the wheel bores with pledge as well for the graphite lubes ?
If it works good for axles why not the wheel bores also. (Just thought I'd ask if you have tried this .)
Y'know, I was wondering that same thing myself. Like, how would graphite perform if sandwiched between two layers of Pledge?

The main "gotcha" in my mind is that it might interfere with the burnishing process.

If I had a test track, it'd definitely be worth a try, though.
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whodathunkit
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Re: Our 2019 Cars

Post by whodathunkit »

You might be right with the burnishing process !
What type of automobile can be spelled the same forwards & backwards?
Derby addict
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Re: Our 2019 Cars

Post by Derby addict »

Vitamin K,
Could you share with us how you made the run out tool?
Speedster
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Re: Our 2019 Cars

Post by Speedster »

Construction of Fat Sebastion's run out tool is shown on Page 64 of Troy Thorne's magazine, Build a Winning Pinewood Derby car, 2013 Edition, $9.99. It can be purchased from Fox Chapel
Publishing Co. It's a Great magazine. Yes, all the answers are on Derbytalk but this magazine will speed up your knowledge of the science behind making a block of wood go down a hill fast.
Your child will have something he/she can refer to at any time. We set a table and spread 12 of these magazines for scouts to look through at all our workshops. We also sell them at our workshops to save the folks shipping costs for those who wish to buy one. It really is worth having this magazine.
Best wises to all you Racers.
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