Major District Rule Change, Gentlemen I need your help.

[Newtoderby]

Ok so Three years ago we entered our first pinewood derby, I posted on here and you guys gave us a lot of great tips and my Then Tiger placed third at the pack and 5th at districts. After absorbing more info from you guys and reading and following 5kids racing, the wolf year he place first at pack and 2nd at districts. Districts was a dog fight between him and the scout who won, both my scout and the other as near as I can tell were running rail runners. The difference between them was minimal, no one else int the field was close. So here we are Bear year. We followed the same rules as last year assuming the districts rules will be the same as the previous two years. This year my now Bear scout was after it and to be clear he did about 95% of the work on the car. We also added in my other son as a tiger this year. So we race and my Bear takes the 1st place with his car beating last years time at the pack level he is stoked! My Tiger who made the decision to change a few things made the wheel base shorter then his brothers came in 4 and still had a very fast car, there were thousandths separating 2nd and fifth.

Ok so we go to check the district rules which suddenly have changed. from last year. Here is the major change:

1. Wheels supplied with the kit must be used, The wheels may not be cut drilled beveled or rounded. You may remove the seam from the wheels. All 4 wheels must contact the track. Wheels cannot ride on edge. No Stickers are allowed on the wheels or hubcaps.

2. The axles supplied with the kit must be used Axles cannot be modified, they may only be polished or lubricated.

Only dry lubricants are allowed.

The Rule change is the bolded underlined part above. Note the rest is pretty standard 5 ounces, standard sizes 7 inches 2 3/4" wide etc

I asked for clarification. We have used the revel wheels that are matched and are bsa made in china before and we have used blue colored wheels.(No colored wheels must be out of the box) In fairness last years car we used blue wheels and that rule was in place and they allowed it. I understand they don't want bought speed wheels which is fine by me.
I clarified some things about the rule above and was told axles can not be modified in anyway. Not ridges, machined, bent etc. I clarified you can not lift a wheel and was told that is correct no wheel lifting and all four wheels must contact track. In regards to wheels not riding on edge the clarification was You cannot angle the wheel or axle so the wheel rides on its edge. It must ride on its full wheel.

Ok so this is where it leaves us now. The car built is a wedge, 1/2" at back 1/4" in the front perhaps a little less. Rear wheels are 5/8" in at the axle. Drilled on a 3 degree negative cant. (Note we don't have a silver bullet block.) we did use the method of a square 2 inch piece of metal on a drill press table with the proper sized drill bit propping the car out to get the three degrees. Front wheels are 3/4" from the front to the axle, one wheel lifted up and the dfw wheel axle bent to three degree and then positive cant and steering is set at about 4 inches over 4 feet. Standard wheel bore polishing with novus 2 and burnished with graphite q-tip, axles polished to 2500 grit and then brasso used. Center of mass is 7/8" from rear axle.

I think that is most of the details. SO gentlemen I ask you with hat in hand, what do we do, how can we make this as fast as possible under those rules.

I feel like they took the science right out of the equation by doing that. To be clear this has been a true father son build, each year my scout has done more, he polished his axles his wheels etc, he understands why we cant wheels and the frictions involved....etc etc. SOrry for the long read but looking for answers Thanks everyone

 

[bracketracer]

I would have the kids build a different car if I was in that position. Drill the rears at 1-1.5 degrees of cant and drill the fronts with intentional toe to get it to steer without bending the axles. You will need to experiment on a spare body to find what angle gets you to the steer you want. I would drill the fronts angled down 1.5 degrees also in addition to whatever steer angle you find. That way you can insert the unbent axles and stil rail ride. With four touching you will make one front wheel the dominant wheel that steers while you set up the other front wheel to steer the same direction but just float, touches but with as light of contact as possible so it rolls but doesn't carry any weight. If you set the steer on the car with the three wheels you want to have touching, when you add the fourth wheel the steer should not change.
What they did with that rule change was make it easier for the families that know how to finesse the alignment to win. You should only lose about .009-.010 with the fourth wheel touching and just a couple more thousandths from backing the cant down in the rear.

 

[Pacfanweb]

Keep using the Revell axles, though. They don't have the flashing and crimp marks around the head.

 

[ngyoung]

From what you described of your current car you cannot use it with those rules. You will have to make a new car. Did the district change the rules before the pwd season? I would think most packs would adopt them as well so there wasnt a big discrepancy like this. My fear is that other parents wont notice the changes and the district chair wont enforce the new rules.

That being said there are some tricks to eek out a little more speed. I would drill the rears with a 1 degree cant. The slop in the wheel bore will allow them to sit flat but they will still migrate to the nail head while rolling.

Steering the DFW will be a little trickier. There are two methods i have seen that can work.

Txchemist has one method... Basically you cut the front off before the axle holes. Take 5 minute epoxy and a big rubber band to re-attach it. Then you wedge paper in the seem on the dfw side to set the dfw toe in to give you your 4" over 4' steer. The 5 minute epoxy should give you the time you need to fine tune it. Once you get the steer set you let it dry, fill any gaps in the seem, sand the edges flush, and paint.

Another is from 5 kids. In his you drill out a hole for a dowel to fit in as your axle holder on the DFW. You the drill the DFW hole at a 1 degree angle into the dowel while it is instalked in the body. You will also want to make an access hole on the bottom of the car where you can spin the dowel. This is how you put a sone imeven will fine tune the steering. You can even put a tiny hole in the side of the dowel where it is exposed from your access hole. Then you can use that sane drill bit as a lever to turn the dowel as you are tuning.

 

[Newtoderby]

Well, I agree making a new car would be best. But the very first rule is you must use the same car you used from the pack race. I clarified and was told but you can modify to comply to the new rules.

Also this district rule change was handed down after some Packs had run their races. They came out a week or so prior to ours we didn't even look at them at the time cause folks were already building their cars.

The fact that In the clarification was all the wheel must touch basically told me we cant even do the 1-1.5 degree cant. Technically. Being Scouts we try and keep everything above board at least in my house. I do think all your tips are the way to go and basically the only way we have a shot, if we are forced to use the same body which it appears that way I will have to have him move the rear axle in slightly to drill new holes, The front wheels same thing I can have him move it forward some.

I will have to have him go these routes and hope for the best.

Its interesting that his brothers car was the same with the exception of he wanted his wheel base. 1 inch back from the front as opposed to 3/4 and his car ended slower and in fourth.

Which tells me there is still the possibility of no matter how great your build a small difference or change can mean a drop in a competitive pack.

Im still at the drawing board

 

[Gtdhw]

"Kind-of" found ourselves in this same position. We agreed to an early (fall) crossover for my Webelo II, before being told that he could no longer compete in pwd, since it will be held in the spring, and he will be Boy Scout by then. Myself, my wife, and and my Webelo II were all present when told this by our pack Scoutmaster. My boy was crushed as he wanted one more shot to get the district title (best of 3rd place). So he decided to build a car anyway for all out speed, and race with me in the sibling race. We build our first cubed car together. It's a 3 wheel RR, with bent axles (2* at all four corners) and a disc'd NDFW. We started our builds in December, so that we could take our time, and just completed them all last week (race is this Friday the 18th). Last Thursday at our pwd workshop/meeting, the Scoutmaster asks me if my oldest is building a car this year? I told him yes, for the sibling race, since he couldn't compete in the pack race. He says "Oh he can race, as long as his car fits the pack rules (4 flat, no bent axles, no RR'ing) since he was Webelo II when the year started.". I was stunned and just stood there. So I go home and tell my oldest this, and he's like "YES!", until he realizes that his car won't work. I tell him that we have a very short time, but pretty much have to build another car in a very very short period of time, or he can just be happy with the one we built and stick with the sibling race. He says that he's willing to build another everyday after school until raceday. Ok then. The next day I drive to get new weights, only to find them out of stock. So that leaves us with one option.....to modify his existing car.

We pulled all four bent axles, and the disc'd wheel. When we built this one, we used the pro body jig, which sets the axle holes very high in the body, and the raised wheel even higher. We cut both ends off of a toothpick, added a drop of water, then installed the toothpick with a drop of glue, in raised wheel hole, and very gently sanded flush. Then we redrilled the NDFW hole using the same jig, in the same 5/8" location but with a few business card shims under the front of the jig. We got it very close and after prepping 4 new straight axles (one being box "straight" and used for steering of DFW) and a new NDFW, we ended up with 11g's on the DFW, and 3g's on the (once raised) NDFW. It was not the preferred method of building a new car, but it's all we could do, and is now 100% rule compliant, and should still be very fast.

 

[Newtoderby]

Thanks for all the thoughts guys. There is a discussion ongoing with the rules. But I am pretty sure though we will be changing it up. I love the ide of a tooth pick to fill and then re drill. With these tips I think we can overcome. at least hopefully. Thank gentlemen you guys are always a wealth of info

 

[ngyoung]

1 degree cant i feel falls within the acceptable range of human error. Just how dead nuts on do you think the average scout car is when they install the axles? Most are more then likely set with some angle in who knows what direction. Biasing to get yours to most likely be tilted in the desired direction i think is skirting the line but still reasonable.