Hello brand new here.

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
Speedster
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Re: Hello brand new here.

Post by Speedster » Thu Jan 17, 2019 8:48 am

It has been said on Derbytalk by very fast racers an Extended wheelbase car is easier to tune. Others on Derbytalk might have opinions.

Derby Evolution Pinewood Derby does a good job on wheels. From what I can tell from your very lenient rules, you have 2 choices.

2.4 Gram wheel (NPWDRL BASX) $22.95.
Precision Turned Pinewood Derby Wheel. $8.95 + $5.00 to remove the outer step.
All colors available.

My choice for the dfw has always been the right front wheel. It is simply my choice. If I am holding the car length wise, looking at the right front wheel with axle at 6 o'clock, I take the special pliers, grab the head of the nail and turn it slightly towards 5 o'clock. I then take it to the test board and adjust the drift for a drift of 2" in 4'. I leave enough of the nail head so I can get the pliers on the head. When I'm all done I push the nail in and set the clearance with a notched Credit card. A sharpie mark should be put on the head of the nail before the nail is bent. This will tell you where the angle is for the bend. If you are allowed to have the groove in the head of the nail you can set the clearance before setting the drift. We are not allowed to groove the head.
The way your rules read I suspect someone is familiar with the Mid America race that takes place around May of each year. I have never seen rules this lenient in scout racing. You are very fortunate.

IMPORTANT. When setting the car to rail ride, the body of the car behind the Dominant Front wheel should be narrowed 1/16". It is done to keep the following rear wheel off the rail.



Sleestak
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Re: Hello brand new here.

Post by Sleestak » Sat Jan 19, 2019 12:07 am

IMPORTANT. When setting the car to rail ride, the body of the car behind the Dominant Front wheel should be narrowed 1/16". It is done to keep the following rear wheel off the rail.

I need this dumbed down or worded better. Wouldnt this make the rear wheel CLOSER to the rail. Do you mean the body where the dominate front wheel goes into?



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Darin McGrew
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Re: Hello brand new here.

Post by Darin McGrew » Sat Jan 19, 2019 1:02 am

I've heard of rail riders where the front of the car is a little narrower. The idea is to give the rear wheels a little extra room so they don't rub the guide rail at all. But you can do the same thing by leaving extra room between the rear wheel and the car body, assuming that you've aligned the rear axles so the rear wheels move to the head of the axle.



Speedster
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Re: Hello brand new here.

Post by Speedster » Sat Jan 19, 2019 6:20 am

No, it makes the rear wheel farther away. Yes, I mean the body where the dominate front wheel goes into.
Please look on Pages 86 and 87 of your book, Build a Winning Pinewood Derby Car. It explains why you do this and has pictures of a car where this is done.

I think we might not have talked about rear wheel alignment. If we have, I apologize.
This will be done when the car is finished and ready for its wheels. Install the rear wheels. No wheels on the front. Lift the car with your fingers under the front of the car, keep the front the same height as the rear, and slowly pull the car forward and then back it up. The wheels should stay on the heads of the nails. If one or both migrate to the body of the car they are out of alignment. The bent nail will allow you to adjust the wheels so they both stay on the heads of the nails.

I suggest you go to Home Depot or someplace that sells lumber. Buy a strip of Pine lattice strip, 1/4" X 1 1/2". I think this is a stock size. No cutting except for the length. After you are finished with everything and the car is ready to race, put the Pine Lattice strip on your very level test board and let the car roll slowly down the board. Watch the rear wheels to see if they stay off the guide strip. If they don't, pull the nail out like Darin suggested. If worst comes to worst, you can try adjusting the toe to force the back wheels to clear the guide strip.



Sleestak
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Re: Hello brand new here.

Post by Sleestak » Sat Jan 19, 2019 8:53 am

Darin McGrew wrote:
Sat Jan 19, 2019 1:02 am
I've heard of rail riders where the front of the car is a little narrower. The idea is to give the rear wheels a little extra room so they don't rub the guide rail at all. But you can do the same thing by leaving extra room between the rear wheel and the car body, assuming that you've aligned the rear axles so the rear wheels move to the head of the axle.
To dumb this down your saying the back 2 wheel not pushed as far Into the wood block as the front wheel yes?



Sleestak
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Re: Hello brand new here.

Post by Sleestak » Sat Jan 19, 2019 8:59 am

Speedster wrote:
Sat Jan 19, 2019 6:20 am
No, it makes the rear wheel farther away. Yes, I mean the body where the dominate front wheel goes into.
Please look on Pages 86 and 87 of your book, Build a Winning Pinewood Derby Car. It explains why you do this and has pictures of a car where this is done.

I think we might not have talked about rear wheel alignment. If we have, I apologize.
This will be done when the car is finished and ready for its wheels. Install the rear wheels. No wheels on the front. Lift the car with your fingers under the front of the car, keep the front the same height as the rear, and slowly pull the car forward and then back it up. The wheels should stay on the heads of the nails. If one or both migrate to the body of the car they are out of alignment. The bent nail will allow you to adjust the wheels so they both stay on the heads of the nails.

I suggest you go to Home Depot or someplace that sells lumber. Buy a strip of Pine lattice strip, 1/4" X 1 1/2". I think this is a stock size. No cutting except for the length. After you are finished with everything and the car is ready to race, put the Pine Lattice strip on your very level test board and let the car roll slowly down the board. Watch the rear wheels to see if they stay off the guide strip. If they don't, pull the nail out like Darin suggested. If worst comes to worst, you can try adjusting the toe to force the back wheels to clear the guide strip.
I'm completely lost. Sorry. Its early.



Sleestak
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Re: Hello brand new here.

Post by Sleestak » Sat Jan 19, 2019 9:00 am

So what is the best or easiest way to thin the front wood where the tire goes in about 1/16 " Just sand it down?



Sleestak
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Re: Hello brand new here.

Post by Sleestak » Sat Jan 19, 2019 9:15 am

Ok I'm out of questions and ready to build car. I'm just waiting for the workshop where I may or may not do anything at. I may prefer at home. My question is what steps do I built this. I'm thinking....

1. Remove some wood weight from under belly of car middle and front by router or drill holes.
2. Weigh car, tires, axles and figure out weight a bit under 5 oz into allow for weight of paint and stickers.
3. Drill weight holes and glue in weights. Puddy over weights. Drill a small hole in back fir final placement of weighted puddy to get to 4.999999999999999999999999999999 oz. :)
Sand and paint car. Apply stickers and spray with clear coat. Car done.
4. Drill car wheel holes.
5. Sand and bore wheel hubs with novus 2 or whatever it is. Bag wheels.
6. Polish axels to mirror finish
7. Bend axels
8. Spray axels with silicone with teflon. I bought a different brand. Will have to do. Let dry 15 min or longer
9. Oil axels
10. Place wheels in car and adjust steering to 2" left every 4'
11. Weigh car and place weighted puddy Into back hole to get to 4.99 or 5.0

When should I do the spray silicone and oil step?
2 or 3 days before race? The night before?

Edit.. move step 11 before step 9.



Speedster
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Re: Hello brand new here.

Post by Speedster » Sat Jan 19, 2019 10:08 am

I wrote this before I read your additional posts but I decided to submit it anyway. It's here if you need it. I'll back up and read your posts.

Not both wheels if the rear wheels are rolling straight. It will always be the rear wheel following the Dominant Front wheel. With the Negative Camber on the rear wheel it will always go to the head of the nail. When you have the car together roll it down a smooth level surface slowly. Watch the back wheels to see if they both stay against the axle heads. Set the car for the drift.
Tape the Pine Lattice strip to the level board and watch the back wheels to see if they stay off the guide strip. EXAMPLE: If the LEFT rear wheel has toe-out it will keep trying to steer the back of the car to the left. If the LEFT rear wheel has toe-in it will try to steer the wheel into the guide strip. You want no rear wheel trying to steer the car.
Try this when the time comes and let us know what the car does.
If your workshop has a Concentricity gauge, and if you intend to use the store bought wheels, check the roundness of the wheels. Mark, or set aside, the worst wheel. Use the worst wheel for the raised wheel. The car will only go as fast as the worst wheel.



Speedster
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Re: Hello brand new here.

Post by Speedster » Sat Jan 19, 2019 10:45 am

Yes, just sand it down. Sand far enough that it passes the front and rear of the wheel. As late as it is you might simply choose to do what Darin suggested. Widen the wheel gap on the rear wheel behind the Dominant Front Wheel.

Do 4 before 3. Actually, I think 4 is usually done before 1. email Vitamin K and ask him if you should tape over the wheel holes and leave the wood bare.

5 -- I would be more comfortable if that read "Polish wheel bores with Novus 2".
I'll stop at Number 5. I would contact Vitamin K and ask the rest of the Questions.

For What its Worth. There are 141.75 grams in 5 ounces. It's easier for me to work with grams and perhaps it will make it easier for you too.

Please let us know where the car balances after it is completely finished and how much weight you were able to add. We've had a lot of success with 3/4" in front of the rear axle slot.
Preferences vary.



Sleestak
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Re: Hello brand new here.

Post by Sleestak » Sun Jan 20, 2019 6:00 pm




leerbennett
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Re: Hello brand new here.

Post by leerbennett » Tue Jan 22, 2019 10:00 am

Top tips for speed.
1. Maximize potential energy with as much weight as is allowable, typically 5.0049999 oz. Here are some products that help get the maximum weight in the right place.
https://www.maximum-velocity.com/produc ... -5-ounces/
https://www.maximum-velocity.com/produc ... y-1-ounce/
2. Minimize friction
An effective use of extra money is to by multiple kits, allowing you to select best performing wheels.
Raising a wheel and finding the right lub are also impactful.

As a race director, I am allowing oil for the first time this year. So I very curious about the practical effect of oil in a mainly graphite race as well. As we both have read, a small dose of the right oil seems to have an edge over graphite, especially for races with more runs.
Race rules typically state that the lubricant should not leak onto the track regardless of type used. This is to protect the track.
So a race environment with graphite flying all around breaks a recommended convention, but drawing a line on too much lube is not terribly easy. Historically I don't think we have run a clean race in this regard. Working on cleaning up our act, but changes to race traditions often comes slowly.
Overall, I would recommend trying oil in our race with just 5 runs per car. If you expect clouds of graphite dust for good reason, your concerns could be justifiable. You may want to nudge your race director into making future races more oil friendly. Reducing the mess from graphite is a very appealing argument for a race director.



Speedster
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Re: Hello brand new here.

Post by Speedster » Tue Jan 22, 2019 10:43 am

leerbennet, I know you're trying to help but this gentleman wants 1st place. If you would humor me, would you please read all the posts previously shared with Sleestak. He has very lenient rules and I already have recommended wheels from a vendor. Yes, oil is faster then graphite and the Mid America race has proven that it is. Sleestak is going to use oil unless he changes his mind. For What it's Worth, I have 100 tubes of BSA wheels and I've checked them all on Knotts Concentricity gauge. Save your money. If your rules are very, very strict, your best chance of getting decent wheels is to buy the Preferred numbered wheels (2, 8, 15) from a vendor and you have a chance of getting at least 3 out of the 4 that will be decent. Check their run-out and use the worst one for the raised wheel.
Thanks for humoring me. Best wishes on your 2019 races.



Sleestak
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Re: Hello brand new here.

Post by Sleestak » Tue Jan 22, 2019 1:49 pm

Yes speedster I want first place but so does every other girl scout. If we dont get first I'll be over it in about 8 seconds. That said I will use every trick and tip I have learned to give us best chances. Except for fancy tires. The pink tires from the girl scout store will have to do.

Yes I'm absoluty using oil.



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Vitamin K
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Re: Hello brand new here.

Post by Vitamin K » Wed Jan 23, 2019 7:27 am

Speedster wrote:
Sat Jan 19, 2019 10:45 am
Do 4 before 3. Actually, I think 4 is usually done before 1. email Vitamin K and ask him if you should tape over the wheel holes and leave the wood bare.
If I'm running graphite, I will leave the wood bare and just rub graphite into the wood.

If I'm running oil, though, I will apply a few layers of CA glue to the body at the spot where it meets the hub and I will polish it smooth, in order to provide a hard slick surface for the oil.



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