What tools are needed to true, lighten and improve wheel performance?

[jatofau1]

Here is my story. Last year we built a car for my son's first cub scout pinewood derby race. This was the first time we built a pinewood derby car which I found to be quite an interesting challenge. We did a little research and did the basic things to build a fairly decent scout car. Our pack rules state that we can only use the parts in the box and no oil. The car won every race and took first place with a time of 3.011 using graphite. Looking back at the car design, we could have done a much better job. Especially after reading many of the posts on this website. Thank you all for sharing.

As we all know, once you build a winning car, everyone wants to know how it was built. As a good sport, we told everyone how we built the car and what we did to make it fast. So this year, everyone will be at least as fast as my son's last car. Therefore, we need to take our building skills to the next level.

I have invested in a lot of the tools last year and even some of the Derby Worx tools. There are a few posts in the forum that imply that the Derby Worx Tools for wheels are a waste of time.

Since we have to use the wheels in the BSA Box, what tools should I buy to help us true the wheels, improve the performance of the wheels and lighten the wheels? (I have all ready purchased all the lube, polish stuff from DD4H) At this point, I don't want to buy a lathe.

Thanks, Joe

 

[GravityX]

Lathe is the obvious choice to perform this operation. Another option would be to purchase a wheel that has already had this operation performed. One could argue the wheel did not come out of the BSA box, but how is that proven? Of course, you could scour YouTube to see the various methods out there, at varying success. Repeatability would be my concern with other methods. It's going to be tough to beat the sale price right now versus producing this wheel yourself. Just a thought

 

[zigzag]

I don't think there is any good way to lighten the wheels outside of someone with the appropriate experience using a lathe. I think most people on here would tell you it takes about 50 sets of wheels to learn how to do it.

I think you can buy a pair of trued / rounded and lightened (if your rules allow the wheels to be lightened) wheels and race those. They will be out of the box just lathed by someone else.

If you are racing on a best track I think a goat boy drill block or silver bullet is the number one thing I would invest in.

 

[Kinser Racing]

If you feel you don't want to buy wheels that have been professionally turned (they are official BSA wheels, just not out of YOUR box), don't touch them. They'll be faster bone stock. Lastly, if you really feel the need to be a total stickler to the rules and just have to use your wheels, I'd email John and ask him if you could send him your wheels to turn.

 

[bracketracer]

Given that you don't want to purchase a lathe and that you want to use what came in the box, the way I see it you only have two options. Either send your wheels out to be turned or sort through several boxes and hand select four wheels that spin true out of the box. Even if you send yours out I would still hand pick four good ones. There's at least one clinker in every box. I usually buy 10-12 sets and sort from there. So far, the wheels I bought this fall look pretty good. Out of 12 sets I have eight really nice wheels.

I wouldn't count on too many families in your pack taking your advice and getting faster. Some people get upset because their kid didn't win but they aren't willing to put in the effort it takes to be on top.

 

[jatofau1]

Thank you for all the advice. We will run the out of the box wheels and see how fast we can make the car.

Trying to lathe plastic wheels seems like a monumental task that requires too much time, skill and customized tooling. I wish I had the time to master this skill because the engineer in me likes challenges like this.

GravityX, I agree with you. It is far more economically to buy wheels.

Thanks again.

 

[pony express]

You can get wheels that keep to the heart of the rules. The slight turning (lathe work) to true the wheel round is important. The giant speed gains come from taking lots of weight off the wheel, but John can just true the tread so it is perfectly round. The weight does not change that much to stay in compliance. Some rules do not allow the hubs to be altered. You have to check your rules closely and if it looks like they allow changes to the hub (step) then do it.
If you want to stick to letter of "out of the box" then do as Kinser said. The plain wheel can be decent. You must purchase a few extra and roll them to find the ones that roll straight. Those are the ones you want. The scout store sell extra wheels so they do not have to be the exact ones from the box you are given.

 

[jatofau1]

I have a bunch of spare wheels from last year. Some how I accidentally order a at least 10 extra sets on line. Don't ask me how I accidentally typed in that extra zero. When I get back from vacation, I will take a look at the wheels to if there are any good ones in the bunch.

 

[Vitamin K]

I'd add that if you're going to be evaluating box wheels, you should build/buy yourself a tool to measure the runout. Since it ruffles feathers of some when I link a certain other forum here, I'll just say that if you Google "homemade derby concentricity gauge" (without the quotes), you ought to find plans for one you can build for about 20 bucks in parts. Alternately, for more accuracy, there's the one produced by Knotty Racing that's precision machined.

You should still spin test wheels, btw. Measure the runout and spin them to decide on how good they are.

 

[GravityX]

Here's a video of the Knotty Racing tool:

[video]https://youtu.be/S4dpf8kmGqo[/video]

 

[jatofau1]

Nice tool. Where can I buy one? I looked on the internet and could not find one for sale.

Thanks,