post race advice for next year

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stay at home dad 13
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post race advice for next year

Post by stay at home dad 13 »

So my son had his first race, took 4 or 5 from what I can tell out of 13 so not bad. I'm trying to figure out how to make next year better. Here is how the car was set up. About 2.5 oz in rear, standard block about 1/2 inch thick. Extended wheelbase. Canted wheels, three wheeler. The track was an old all wooden track with 6 lanes with no center rail only side rails. I set the car up to run straight with a very small drift, which I inset the rear wheel on that side to prevent rubbing on the outside rail. I took some stills going down the track but didn't think to take video. In the pics car is running straight down the middle. Even with the other cars down the first half. So I'm thinking that I lost speed at the bottom. Com was about 1 inch maybe less. I polished the speed axles and smoothed out the wheels, that's all they would let us do.
What I'm think the things to improve on are, Keep com closer, another possible problem is that when we weighed in we were .5 oz over. So I remove a large section of wood in the middle and front of the underside of the car. I wood glued the axels in place, The end of the track was just 2 towels to stop the cars, several of them bounced backwards possibly messing up the wheel alignment due to the extended wheelbase.
The wood track was only about 30 feet or so, track time were around 2.67 and all race times were very close but seemed to loss or not gain any speed on straight section.
Any thoughts?
ngyoung
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Re: post race advice for next year

Post by ngyoung »

How did you polish the axles? It's easy to over polish with the lower grits if you haven't done it before. We're all 3 wheels canted like this /----\? Does smooth out the wheels mean you polished the inner wheel bore or the wheel tread? We're you using the slots or drill your axle holes?
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Re: post race advice for next year

Post by Speedster »

Unfortunately, we all lose speed at the bottom, some much more quickly than others. No one ever increases speed. Bore prep is very, very important. Lots of good advice in the "Search" function. I would get rid of as much wood as possible and put the ballast in the rear, 2 ounces behind the rear axle slot and 2 ounces in front of the rear axle slot with a CM of perhaps 5/8" in front of the rear axle slot. I'm assuming you're racing Cub Scouts. The 2009 mold wheels are fairly good and some are quite good. Sanding them might be doing more harm than good unless you have a concentricity gauge to guide you. You seem to have lenient rules which will allow you to build a car that looks like a Hershey bar. That model seems to be the ultimate for speed. If speed is your Team's only goal I would study the construction of the Hershey bar cars on the search function. Best of Luck for next year's race.
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Vitamin K
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Re: post race advice for next year

Post by Vitamin K »

Dealing with no-guide tracks is an area that I have very little understanding of. Can somebody explain the basic theory to me? Do you put negative cant on the DFW and toe it out, so that you steer into one of the side-rails?

Boo on those wacky tracks.
stay at home dad 13
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Re: post race advice for next year

Post by stay at home dad 13 »

Thanks guys
This is a cub scout pack
I only did a lite polishing of the axles because they didn't have burr or crimp marks on them, that is what they gave us. But I still ran 1500 grit paper on them and some general rubbing compound that you would use on cars. The wheels, I was only allowed to smooth out the wheels without taking any weight off. So I spun them in my dremel and touched them with a green pad. Inside hub, I used the same rubbing compound then graphite. I drilled my own holes as far to the edges without going past the 7 inches.
The track seems very old. There are no center rails, only side rails like curbs that keep the cars in their lane. From my understanding, you set the car up to ride on this track similar to how you would with one with a center rail. Rear wheels canted out and inset on the side that is going to ride the side, and the front canted out with toe towards the side you are riding. I set mine up so it took longer to ride to that side compared to a center rail rider. so for the most part it was a straight running with a slow drift to the outside rail on the aide with the rear wheel inset.
Maybe others just flat out did a better job and made a faster car, we still had a good time making it and it's now an everyday toy that we made
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Re: post race advice for next year

Post by ngyoung »

Ok some things to keep in mind for next time...

You did the right thing in-setting the rear wheel on the DFW side and steering toward that side. You do want both the rear wheels and the DFW with negative cant. A center rail car the DFW is canted opposite if the rear.
Negative cant= /---\
Positive cant= \---/

For polishing axles without burs I would start at 600-800 grit. Only apply for around do 15 seconds. Then progress to 1k up to at least 2.5-3k for graphite.

For wheels I would leave the treads alone. Focus on the wheel bores only. Don't polish wheels spinning at high speed. It can melt the plastic.

I highly recommend checking out 5kidsracing.webs.com specifically the scout workshop which covers axle/wheel prep that is the basis of what even successful adult league racers use.
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Re: post race advice for next year

Post by sporty »

E. Mail sent
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Vitamin K
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Re: post race advice for next year

Post by Vitamin K »

Did you have any method of verifying/tuning your rear alignment? Cars don't really "get loose" until you make sure those rears are working together.
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Re: post race advice for next year

Post by Speedster »

Do the inside of the wheels say "Made in China" by any chance? I'm curious why the nail has no casting marks. Is the point end of the nail smooth as opposed to a chisel point? You stated, "That's what they gave us". I'm just being Nosey here. Did you not receive a sealed box of the Official BSA kit? Are the wheels BSA wheels ?
stay at home dad 13
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Re: post race advice for next year

Post by stay at home dad 13 »

The kit they gave us was from maximum velocity in a ziplok bag so they bought in bulk. I found out that they gave everyone speed axles because I think there are alot of single moms in our pack and wanted to help keep things even as possible. Wheels were also from maximum velocity with mold numbers on the inside. Looking at their website I put the best matched pair in the rear.
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Re: post race advice for next year

Post by BallBoy »

stay at home dad 13 wrote:The kit they gave us was from maximum velocity in a ziplok bag so they bought in bulk. I found out that they gave everyone speed axles because I think there are alot of single moms in our pack and wanted to help keep things even as possible. Wheels were also from maximum velocity with mold numbers on the inside. Looking at their website I put the best matched pair in the rear.
You have a great kit with, in my opinion, far superior wheels and axles to the BSA kits. With the MV axles I just use micromesh sandpaper finer than 2000 grit followed by Mother's mag & aluminum polish. For the wheels in a typical children's race, you don't really need to do anything, although polishing the bores helps. In my experience, unless you have high-precision tools, working on the wheel tread frequently makes the wheels worse than unworked wheels.
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Re: post race advice for next year

Post by Speedster »

Thanks for answering. I know Maximum Velocity (Randy Davis) has his own kits. Just a couple more questions. Do the wheels say -- BSA PINEWOOD DERBY -- on the outside or are they the wheels Randy has made for his kits ? Is your Pack eligible to race in a District Race? I agree, if they are Randy's wheels it would keep someone from buying aftermarket wheels. Whether Randy's wheels keep things as even as possible would be a Topic for discussion. As I think about your Topic, you're looking for an edge for speed and I am too and there's nothing wrong with that. That's why I'm on Derbytalk 6 times a day, year around. I don't want to miss anything. The Derby is my year around hobby and has been since 1985. What interests me a lot is that you race on a track that was not designed by Don Murphy and you use kits that do not benefit the Boy Scouts of America. You and I know the ones who put in the most effort, have the correct knowledge, are going to win. Many rules, like the "4 on the ground" rule, benefits the skilled builder and hurts the young scout who probably breaks his car trying to get the 4th wheel down. Good people, with good intentions, do the exact opposite of what they intended.
I invite your leader, or leaders, to email me. I would like to hear their story.
Best,
Bill (Speedster)
ngyoung
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Re: post race advice for next year

Post by ngyoung »

As for getting MV kits over BSA kits I think it is fine for a pack to do so if they choose. I think it does even the field a little and eliminates a lot of flaws inherent in the BSA kit. There are plenty of other ways to support your district/council.

The families that put in the work will usually always win no matter what rules or parts are supplied. The only way to really make positive change is to provide workshops to teach everyone and allow access to the proper tools used in pwd car building.
stay at home dad 13
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Re: post race advice for next year

Post by stay at home dad 13 »

The wheels say maximum velocity on the outside and the inside with the mold number. I did find the track's age and design funny comparing it to every other track out there. I don't know much about my sons pack. This is his first year and so far I'm not that impressed about the amount/or lack of, information and communications given out. But that's another topic. I'm just trying to figure things out on my own about these cars. My son and I had fun with the build and he designed it with his theme and did a good portion of the work. I'm more focused on the car than he is.
I was just looking for things I might have done wrong, or not enough of, and how to improve for next year if he continues.
Sorry for sturring the pot and opening the can of worms
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Re: post race advice for next year

Post by Speedster »

You need not be sorry for anything. Thank you.
The Laws of Physics will apply to Max-V's kits the same as the BSA kits. I have no doubt there are those who have experience racing on that type track. It has been talked about before on Derbytalk. Everyone is on your side. You're having fun with your son and that's the most important thing. I wish you and your son the Best in all your future racing.
Cheers,
Bill
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