My son Justis and I have been working on his car. Last year he did alright, but this year I would love to see him win it all. Today we will be machining down the axles on a lathe to ensure a uniform and smooth contact surface. We will also be taping the inside of the wheels to create threads that will be packed with graphite. Any other sneaky, but ethical advantages you guys can think of?
drilling the body and strategically adding weights to enhance the acceleration at the start, but not too much to inhibit the coast in the flat. close to the max weight allowed
Get to the maximum allowable weight, and keep it low in the car. Drill some holes, fill them in with melted down fishing weights, and epoxy over them to keep the lead in place. Put some right over the nose. It works wonders. I always made mine look like early Indy cars, so there was a lot of weight to be added to get to the maximum allowable. Also, make sure there is ZERO side to side play in the wheels/axles, but be careful not to create any resistance, either.
my dad used to paint them just like a car primer, paint, wet sand, wax, i think he also moved the weights up to the front, we always took 1st or 2nd place
On the underside: Over the nose, between the front axles, and between the rear axles. Keep it centered, and make the holes wide and shallow, not narrow and deep.
Right around front axle. Trailing to rear axle. 70/30 distribution front to back Worked for me. Also helps to make the body super thin (vertically, think old F1) and bring it up to weight with weights. Don't know if they're on to this yet but I made mine with a forked nose. Car sat a few wheel lengths ahead of the others in the gate, but i was a punk when I was little.
"maximum-velocity.com" Tungsten is the best, of course it costs the most. Plenty of kits, parts and ideas there. Subscribe to their newsletter good information for building and tuning your car. "derbytalk.com" Packed full of PWD genius" there. Good luck, don't forget this is supposed to be fun.
Use left and right hand threaded taps for the left and right wheels. Theoretically the wheels should run out away from the body to avoid rubbing against the lane guide.
Don't know if this was mentioned Tune the car to run on 3 wheels, right front a little higher than the other 3........less resistance Put the wheels on a drill, use wet sandpaper and make them smooth
Isn't your son, the one who is suppose to be making the car. That is suppose to be the whole idea behind a pine box derby. The kid get the enjoyment of building and racing something they made. Good luck and hope he wins.
I don't know about now but when my 35 year old son was playing with pine wood derby's, you had to buy a kit and use only the parts in the kit and there were strict rules on what could and could not be used. I would hate to see him disqualified over axle grease. Check your local rules before you build. I drilled his body for axles in my drill press to make sure each axle was in alignment to each other. Other than that he built the rest himself. I did build one along with him for the dads class.
Best place for weights is in the back of the car, with the CG approximately 1" forward of the rear wheels. This will allow maximum potential energy with the weight "falling" down the track longer than those cars with weight displacement forward. This explains why some cars seem to "push" past the opponents down the straight. So why not place the weight behind the rear wheels? Because then the car becomes "skittish" and the front end won't have enough weight to track properly. Since most local and district rules prohibit any change in the wheelbase (otherwise my suggestion would be to run an altered, lengthened wheelbase), I would suggest you cut the the back of the car and glue it to the front. This will shift the wheelbase rearward (but not modify the length), allowing more weight rearward without the adverse affects of handling often seen when weight is too far behind the rear wheels. This trick effectively makes it impossible. Additionally, your car will track straight, which is very important, unless you plan to build a rail rider. For my last tip short of what are "known" rules to be competitive such as polished axles, polished wheel bores, tapered rims, touch free bodies, 3 wheels (often not allowed), cambered wheels, and maximum weight is to minimize axle friction. Make a paste of rubbing alcohol and graphite. Pack the wheels hubs and axles with the paste. Allow to dry overnight. Shake out any loose graphite. This will create a graphite pseudo-bearing for the tires to ride on, and I say pseudo since bearings and bushings are normally strictly prohibited. Additionally, using this method I have found the car will get faster as it runs and won't require a relube of graphite which often can not be done after the intial checkin. Good luck and have fun.
Anything to reduce friction "Outer wheel surface may be lightly sanded, shaved, or polished to remove surface imperfections and mold casting burrs" Can brass washers be used between the wheel and the body like CO2 cars use? Check the track on race day for imperfections to see if one side has an advantage. Smokey Yunick "You don't race cars, you race the rule book" Good Luck! Larry
Don't forget using a very accurate gram scale when you are getting the weight right. And let the kid do some of the work on it himself.
think your all missing the point of the pinewood derby. it's about kids having fun and competing with there friends. when their fathers have to start machining parts it becomes dad trying to win something, not the kid. and that's pretty sad.
Back when I, I mean my son, was building pinewood cars, I, I mean he, would chuck the axles in a lathe and polish them with oiled 600 grit wetordry. I, I mean he, would also undercut the head of the axle to remove the two stamping lines that are left when the head of the axle is formed. I, I mean he, would also turn down the head diameter a bit to make them round. I, I mean he, would also do the three wheel trick. I, I mean he, would also place the weight to the front of the rear axle. Some of the dads, I mean kids, would turn the wheels down to narrow the contact patch. In spite of this being against the rules in the pack, they let these cars run anyway. We, I mean my son, always finished in the top three in the four years he competed. Pics of some of the cars:
as a kid me and the ole man put together acouple winners and we slicked up the axles/wheels, maxed out the weight, killer apint job, etc. here recently i got the privilege to do so with my kid and proby did more than i should but hes just a tiger and i wanted to really spark some interest in fabrication beings this is one of the first things i remember building with my old man. well i did all the same old tricks that were done on my cars and we got our asses kicked. i felt pretty crummy but the kid had fun and thats all that mattered. i have no idea what the other kids did with thier cars but i had alot of time polishing and lubing the wheels/axles. not that long ago i discussed the theory of weight placement in my college physics class and according to my teacher and his demonstrations it makes no difference the placement of weight....
Square up the sides of the body to each other. then put the body in a vise on a drill press or a mill and drill small diameter starter holes for the axles, that way they stay square to each other. No alignment problems.
My son built the car himself and will be running the lathe as well. All him, with a little guidence from Dad.
YUP!!! We just did ours (we call them Kub Kars here) the ones that had one wheel slightly higher were top finishers. We do a tech night with my pack, I use stick weights (alloy wheel type) to find the best place to weight the cars, we have found that some cars do better with the weight on the back. Just to throw a wrench in there,
This brings back memories... I won the championship gold medal when I was a cub scout. I still have the car... My own sons have done well too, but I am NOT one of those dads who builds the entire car for his boy... In our area they have created an "adult division", so the dads can have it out against each other. My dad helped me build my championship car back in about 1978 or so. The car is essentially a wedge shape with radius up both front and rear. My dad helped me drill 5 holes in the bottom for lead weights. One hole centered between the front and rear axles and two holes toward each axle out toward the edges. We used lead balls from blackpowder rifles. I think they were .50 caliber. The car was right at the 5 oz. maximum weight and went very fast. I don't recall spending alot of time fussing with the wheels aside from just making sure the axles were aligned straight, but we used alot of graphite and it just kept getting better every run...
It depends on the track they use at your derby and whether it is aluminum and smooth as opposed to wood or something else. If the track is smooth the three wheels touching idea is very effective. If the track is bumpy the car will have difficulty recovering its lane if only three wheels touch. I would only raise the right front wheel about the width of the axle or less so it can help if the car hits a bump. Weight should be centered just in front of the back axle. place some behind the axle and some in front of the axle. You want the weight as high up the hill at the start as possible. But, if you put the center of weight behind the back axle the car will shimmy too much on the straightaway and loose speed. There are ways to machine the wheels so only the edges touch the track. You need to check your local rules on whether that is allowed. I have run a car like that and it was super fast. longer wheel base is better to avoid shimmy and to give you the opportunity to move the center of gravity further back. Check your local rules. Most important thing. Do not use the factory axle slots in the block. Drill your axle holes with a proper guide and install wheel and axle with proper spacing from the block. Once installed roll the car ONE time to make sure it goes straight. If it does do not let any one roll it or play with it before the race. Each time those wheels roll or hit something the axle alignment is impacted and you loose significant speed. Dan
What are you talking about? I want my car to win. Of course, I race in the Dad's race but we have to follow all the same rules.
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