Derby Talk

Our family officially retired from the Derby when they bridged over into Boy Scouts last year. Last Saturday, a neighbor asked me if I would help her son build a "fast car". Their only Derby experience resulted in the boy's hastily made car losing a wheel and him not finishing the race. With one week to help him, he's now ready for his weigh in on Friday.

His car is named the 'Max D' in hommage to a similarly named monster truck. It's short for Maximum Destruction, which is what we're hoping his car does this Saturday to the competition!

Specs:

Sporty Spoon Design

4.96 Ounces Assembled, before trim weight (23 cubes, DFW on left front wheel)

1/2" COM

Polished the axles that came in the box (400 through 8000 grit), then Brasso Polish

Full weight wheels, with no machining of tread or hub (per the Pack rules) Novus 2 / Novus 1

Steer tuned to 4" in 4'

It was a whole lot of fun to show the neighbor's kid how to make a fast car. I showed him the Pinewood Derby Physics You Tube video before and after the car's construction so he could better understand why we did what we did to the car. It was a pleasant and unexpected surprise to be back in the workshop this year helping make a new derby racer. Glad I kept most of my tools!







Scrollsawer

Very nice job with the Max D car.
The smile on his face is priceless and makes it worth while.


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Thanks Whoda! I asked him at the very beginning if he wanted a design-ey car, or if he wanted a fast car. He said he wanted to go fast, so I breathed a sigh of relief since it's much easier to build a fast car in a few days than it is to build a 'shape-based' car in that short amount of time.

Very nice. 23 cubes with full weight wheels...thats one thin spoon.
Best of luck. I think should add a balsa pig just for fun!
Noskills

Seth, I think we need to take a concerted run at this next Mid America!

Scrollsawer

Scott,

If Mike (Birddog) is not there to kick my butt again I might give it a go. One last ride. Pack race is tonight!

Seth

Good luck at the races Seth, and get some pics. of the event posted so we can share in the festivities!

Scott

Scott,

When it comes to the kids..
I like the simple but fast car designs that are not to much for them to take on for there project.

For myself.. well I like tinker with the designs and the details and I realize that the cars and truck designs
that I share here on Derby Talk from time to time may be way to much for them to take on for there project cars.
For me it's a way to relax at the end of the work day.

Good looking car

Looks Nice and best of luck tonight!

I guess I get to learn more...I thought that the cubes were 1/4oz each. How can one have 23 1/4oz weights in a 5oz car?

Gtdhw wrote:Looks Nice and best of luck tonight!

I guess I get to learn more...I thought that the cubes were 1/4oz each. How can one have 23 1/4oz weights in a 5oz car?

Gtdhw,

24 tungsten cubes equals 4.0 oz. Everyone's weighting goal for a fast and stable car is rear-mounted weight equivalent to 24 cubes (4 oz. of weights, and 1 oz. of car).

Maybe you're thinking that they are 1/4 inch in size?

Scrollsawer

whodathunkit wrote:Scott,

When it comes to the kids..
I like the simple but fast car designs that are not to much for them to take on for there project.

For myself.. well I like tinker with the designs and the details and I realize that the cars and truck designs
that I share here on Derby Talk from time to time may be way to much for them to take on for there project cars.
For me it's a way to relax at the end of the work day.

Good looking car

Whoda, some of the designs you make are way too much for even an adult like me to take on.

I'm just a guy who likes to help make fast cars, but some day I'll try something with 'design ambition'.

Keep on buildin'!

Scott

Will do! You do the same.


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Noskills wrote:Very nice. 23 cubes with full weight wheels...thats one thin spoon.
Best of luck.
Noskills

Our trick in making a thin spoon is to rout out the underside of the car body (versus long, drawn out sanding of the top to bring the top down). This gets the car thin fast, and is much easier than sanding the top, all the way down.



Scrollsawer

FWIW, on my scale, 1/4" tungsten cubes from Max-V weigh as follows:
1--1/4" cube weighs 0.1680 ounces or 4.76 grams

The weight of a single cube might vary a bit but not much. I think 24 cubes will always give you 4.0XXX ounces.

If I might offer something for newcomers. I think it has been suggested for a stock (4 3/8") wheelbase car the added weight should be between 3 to 3 1/2 ounces of added weight with 1 1/2 ounce behind the rear axle slot. I hope I have that correct because that's how our team built this year's car.

Our Neighbor's race was tonight. Was really happy to see him win 1st Place, Bear Rank, and 1st Place Overall. He's got a lot to be proud of, and he put a lot of work into his car build.



An interesting thing happened during the race. The nice gentleman that the Pack uses to run the Derby probably needs to get a new track. Even though our neighbor's son won the race by 4 100th's, his car jumped the lane 3 times in a row before recording his third run time (which I am sure did some notable alignment damage to the car). His average speed in all four lanes was 3.07 (axles out of the box, and full weight wheels running Hob-e-lube graphite), but I'm pretty sure his car lost a few hundredths after jumping the lane three times. The issue was the DFW wheel was riding the rail, and it kept hitting a misaligned track joint on the way down. That had to mess up the DFW wheel after three crashes on lane 3 before successfully completing runs three and four. I am going to try and get a copy of the race results to see if there was indeed a drop in speed from lanes 1 and 2 before the crashes.

I knew we had a good chance of doing well regardless, so we just sat back and let the crashes happen, and let the race administrators eventually figure it out, but if it were a hyper competitive Pack running a lot of fast cars, it really would have been an issue. Frankly, I think the gentleman who runs the race needs to invest in a new aluminum track. His is looking pretty beat up.

I guess we'll turn our focus to him racing in the District Derby now, but he probably needs an axle/wheel re-build first.

Scrollsawer