need advice on making some Pinewood derby cars

MB165

MB165

Active Member
#1
#1
Hey gang,
My kids and I are getting ready to make some pinewood derby cars. He's got to do most of his by himself, but there is a adult class too, so I want to make one for myself and my daughter.
Anybody have some designs they care to share or post up? I need some inspiration. Any tricks or tips would be greatly appriciated.

Pete
 
GSbiker

GSbiker

Active Member
#3
#3
The shape makes no difference in speed. Paint the block of wood yellow and call it a school bus. Save yourself a lot of time. kbs8ball's suggestion is all that matters.
 
joekd

joekd

Active Member
#6
#6
I disagree on shape, you want it as low as possible and 95% of the weight over the rear axle, check all nails (axles) for straight, sand nails to ensure low friction. Use the black graphite lube only (no white garbage)

My son took home regionals twice and set a new track record with a couple of our pinewood cars
 
buckeye

buckeye

Well-Known Member
#9
#9
There is another thread about this sometime in the past few months. There were some great ideas there as well.
Loved the Derby.
 
joekd

joekd

Active Member
#12
#12
Here's ours from over the years

1st car, son was into power rangers and monster trucks, wanted a power rangers grave digger. Wasn't fast but did have working lights (LED's with watch battery packs mounted on the bottom)



2nd year, went out for speed and looks, had about 10 coats of clear on this one



3rd year, this was the fastest car we had, this is the one we set track records with. Actually had parents coming out to examine the car to make sure it was within rules when we went to regionals



Last year, we went for speed and had fun, this was the screamer



This is the shelf on my basement stairs, all his cars and trophies



Here is my #1 best advice for you. Decorate a shoebox to match his car and carry it in there. While the other kids are rolling theirs on the dirty floor and into each other your son's will be safely inside the carrier.
 
toomanytoys

toomanytoys

Well-Known Member
#14
#14
Make sure the nails are lubed and polish them up very well. I used dry silicone spray lube. Make sure the car roll perfectly straight. We always put the weight in the back third of the car.

I won local and a regional as a kid. Good times. I still display my trophys. Good memories of me and my dad.
 
R

rodney

New Member
#15
#15
My son was in scouts for 2 years and never lost a race. We added all the weight to the front of the car to almost bring it up to max weight. We then would get the wheels to spin very freely on the axles. Used graphite to help. Then the most important thing is to get it to track straight. I would take the kitchen table and set one end up on bricks. Run a strip of masking tape down the center. I was on one end my son on the other. Continue to roll the car down the table and make adjustmets to the axle untill it tracked straight.
 
wayne

wayne

#16
#16
with my boys i helped them on the weight deal,that is very importaint what on
to what others have pointed out, i would even take them to the drug store,
i trusted there scales, good luck to all the kids that try. wim or lose the kids
are winners! :thumbsup::thumbsup:
 
Oldsalt

Oldsalt

Well-Known Member
#17
#17
In EVERY form of racing it is absolutely necessary to 'cheat'. If a child wishes to do a ANY form of motorized competition in the future it is necessary that he learn as soon as possible that he MUST cheat if he is to be competitive with the other cheaters. The old saw: "It's not whether you win or lose...but how you play the game" is simply not valid. He must also learn never to talk.

The wheels, which the rules say can't be altered MUST be trued up to be concentric with the axle hole. The tread on the tire MUST be ever-so-slighty 'crowned' so that a minimum of plastic wheel is touching the track surface and then only in the middle. The sides of the wheel MUST be true and free of any roughness that will slow down the car unnecessarily when the tires touch the track's side rails. No car runs the entire course without touching. The inspector will not notice this as most don't look very close--especially if the alteration is VERY cunningly done and the wheel polished in the altered areas to obliterate any 'dull' areas in the plastic that were worked.

The axle hole will be too big for the POS axle as supplied. It must be plated repeatedly [nickle will work just fine] until it fits better and is polished smooth. The bore in the axle must be doctored. The graphite lubrication [mentioned above] is the only way to go. Have tried bushing the wheels with well disguised teflon bearings. Had mixed results.

On of the major things that reduces the speed of a car is its scrubbing it's right or left front tire on the side rail of the track. It has been absolutely proven [to me at least] that a 'slight' amount of 'wobble' in both front wheels will, when the car touches the side rail, it is 'steered' away and thereby loses a minimum of energy by shortening the length of time it 'scrubs'. Extensive testing by a guy [a dedicated, sheep skinned engineer with a complete track for extensive testing showed me this issue. He rigged electronic timers to a data recorder for his studies. He was by boss in an R&D lab working with machine vision]. This was a new one to me and all of my children's cars and grandchildren's cars in the last 35+ years were highly 'tuned'. His was the first and only development program that dealt with this issue, to the best of my knowledge.

As mentioned above...the maximum amount of weight should be at the REAR of the car. It is [somewhat] obvious that a higher % of the car's weight will thereby enjoy a [very slightly] longer down-hill run!. The lighter front end will help lessen any scrubbing on the track side rails and more quickly allow the car to start moving toward the center of the track when it does occur.

Be sure to make the car as CRUDE in workmanship as you dare. That tends to deflect the seriousness of the inspection. [That kid with five thumbs has gotta be to simple minded to cheat]. FOR SURE have a foxy 'mother' attend the youngster during registration and inspection. The bigger the tits the better.

I always thought a tiny magnet in one rear wheel that triggered a tiny sensor inside the body that would, by use of a tiny battery, charge an electromagnet to give the tiny magnet a tiny repulsion at one point in the wheel's rotation. It would be such a small motivation it would not be anything other than a 'racer's edge'. The battery could be installed and a piece glued over it and then doped to the color of the car. All this in the school parking lot. At one time I speced the parts but never [honest] did it because that would be cheating.
 
Scottessey

Scottessey

Active Member
#18
#18
That magnet idea sounds killer! :thumbsup:

I agree with the graphite lube and make sure there's no well-intentioned scout leaders oiling your cars for you. I've also heard of slightly countersinking the wheels to minimize the contact area on the axle.
 
buckeye

buckeye

Well-Known Member
#19
#19
Wow,oldsalt, that is unreal. For pinewood derby?
Unfortuanately, in all aspects of life there will be those that get an edge wheather honestly or by "cheating". So again unfortuanetly, we have to be dishonest to win.
Wish I had a young son, now. We would kick ass.
 
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