New to the forum, first post and a few questions **Race Recap Pg. 7**

[Ironcar]

Good Morning,

Thank you for allowing me to join your forum. My 6 year old son and I are preparing for his first race and because of my work schedule I am now in a time crunch to get it done. His race is this Saturday night. To keep this simple and not too wordy, how would you go about building a competitive scout car in four days? The rules for his pack are pretty relaxed, pretty much the only thing not allowed is wheel shaping. Everything else is standard BSA rules. A little about me, I am an automotive repair shop owner and technician, I have built derby cars in the past, but the last one was in 1991. I chose the name ironcar for the forum because my son loves Iron Man and Iron Car is what he wanted to name his car this year.

Here is what I have planned
Wedge body
Polish axles
Add weight to center of mass
Clean up and polish wheels
Graphite

I'd like to make the car a rail runner, but I'm not sure that's feasible given my time frame and lack of tools.

Again, I appreciate any advice offered and the opportunity to be here and learn.

 

[3phase]

http://5kidsracing.webs.com

 

[Vitamin K]

Interesting challenge, given your short time window. You might be limited as far as what accessories and tools you'll be able to acquire in that timeframe.

Possibly consider a tungsten canopy for your weight addition? Dealing with weight pockets and suchlike is time consuming, and a canopy can give you a reasonably good CoM with minimal fuss. Especially since it's at the scout level. I believe that the BSA stores carry them.

If you're interested in making a rail runner, you need the following: A method for canting the rears, a method for bending axles (for the DFW) and a tuning board for checking your alignment and drift. The 5kids link that 3phase shared is an excellent resource.

If you want to kill some of the axle prep time, and you have a Michael's or a Hobby shop near by, see if you can find a set of BSA-licensed wheels and axles by Revell. The wheels are not so good, but the axles require only minimal filing (to remove the head flashing) and then can be polished and installed. They're also rounder and straighter.

 

[Obsessedderbydad]

Here is what I have planned
Wedge body- excellent place to start. "Thin to Win", but a wedge design is probably the best place to start.
Polish axles- Always. There's probably 100 threads started on here, mostly saying the same thing about polishing. If you cant find help on this, mail me and I'll help you out.
Add weight to center of mass- Not sure exactly what you mean here. You want the weight towards the rear of the car. Dont be too aggressive. You measure this by the COG of the car. 3/4"-1" infront of the rear axle is a great place to be for scout races.
Clean up and polish wheels- I was just looking at these threads yesterday. Same as the axle threads, most of them say the same thing and there's 100's of them. Same advise, cant find what you're looking for mail me.
Graphite- John's in the best, but in a time crunch, use what you have. Burnish the wheel bore, inner and outer hubs. DO NOT APPLY TO THE TREAD OF THE WHEEL. Keep that surface clean.

I'd like to make the car a rail runner, but I'm not sure that's feasible given my time frame and lack of tools.- You can still somewhat achieve this. Using the slots on the block of wood you can angle the axles to give you some what of a cant. If you're unsure about this or don't want to risk trying something you haven't done before, leave the rears straight and just create steer with your DFW (down front wheel) by bending that axle then tune your car to 3"-4" over 4'.

Again, I appreciate any advice offered and the opportunity to be here and learn.

3phase hit the nail on the head. Scotts website is a very good place to start. I'll try and help where i can with what you have to work with in the amount of time you have. Above all things, you've come to the right place for help. While your car is not going to be ideal because of the time contrant you're under, your future cars will be a lot faster with the information you gain from this site.

 

[ngyoung]

First thing I would do in your time crunch is determine what weights you will use and how you will install them in the car's profile. Plan for around 3oz of added weight for a wedge with a little room to add more if you need to and to adjust the center of mass balance point.

Cut or drill out the pockets/holes for the weights before cutting out the shape of the car. adding them to the bottom is preferred. Tungsten will be the easier but it the most expensive and not often available locally. If you have a hobby lobby nearby some stock the big pack of round tungsten tuning weights and using the 40% off coupon you can get them for a decent price.
http://shop.hobbylobby.com/products/3-ounce-cylinder-tungsten-incremental-weights-773432/
https://m.hobbylobby.com/coupon I've bought a lot of stuff for pinewood derby 1 item at a time with this coupon.

Lead is easy to shape and cheap but not safe for kids to handle. If you use it install in the body and cover so the kids don't touch it. The lead free pinewood derby weights you need a lot of to get the car up to 5oz.

The link to 5kids site that 3phase posted is probably your best bet for going through the whole wheel/axle prep and tuning the DFW steer if you go to the scout workshop page. There are other pages on the site that offer more examples of weight placement using different sized weights.

Setting it up as a rail rider takes as much time as it does to try and make it a straight runner. If you want it to go fast you need to take some time to set the steer. For the rear wheels do what was already suggested and push the axles in at a slight angle so the wheels in the rear look like this /--- Some have had success adding a little paper wedge in the slot to help the axle go in at an angle or have a small screwdriver or needle nose to pry up the axle tips. You don't need a ton of angle, just enough to get the wheels to migrate to the axle head instead of the body. You want to do a roll test to make sure they go to the head when rolled forward and backwards.

 

[Crash Enburn]

When inserting the rear axles, try to instill an angle to them (about 3°) as you insert them. Be very aware and careful when attempting to "pry up the axle tips". I have seen many slots break open when trying to force the move.

As far as weighting goes, tungsten is very heavy and very dense. And very expensive. If you go that route, plan ahead for how you can remove the weight(s) to use again.
Lead is denser than the non-tungsten weights, and easy to work with. I originally used fishing weights hammered a bit to fit into a 3/8" hole (that can then be covered with a 3/8" plug). Currently, when using lead, I use whatever lead I have available (a friend who owns a tire shop gave me 20# of used tire weights). I now melt the lead (outside!), and then pour it into the body. If you use holes drilled into the body, don't go smaller than 3/8" as the molten lead will block itself and flow everywhere but in the hole. I have chiseled/routed pockets into the top of the body, filled them with lead, and then glued a sheet of 1/64" wood over it.

You want your weight as far back in the car as you can get it, while still having a Center of Mass* (CoM) at 3/4" - 1" in front of the rear axle line. *The CoM is the point at which the car will balance on your finger/pencil/etc.

Decoration: You can get body coverings (camouflage, spiderwebs, flames, etc.) from the Pinewood section at hobby lobby. You can print your own using the printer label sheets.
Or you can paint. I *highly* recommend using a scratch-filling primer you can buy at an auto parts place (like Dupli-color); it will do a great job of covering the wood grain. Use a lacquer spray (again, I prefer Dupli-color) to paint the body. The lacquer dries very quickly. If the directions on the can say "recoat within 2 hours or after 48", DO NOT USE IT. You'll have fingerprints and smudges all over your car in no time.
If he wants, give your son some paint pens and/or stickers to further decorate his car.

Lubrication: for this first go-round, graphite. DerbyDad4Hire's graphite is the best, but the commonly available Hob-E-Lube is very fast. Don't be stingy in applying it within the hubs. Put graphite in. Spin the wheel. Put more graphite in. Spin the wheel. The graphite will get everywhere, so do it over a newspaper.

If you want to clean the body off again, WD40 will clean the graphite off. Olive oil is said to do the job, too.

 

[Ironcar]

Wow, thanks for all the great replies. I spent a bit of time on the 5 kids site yesterday and I plan to incorporate as many of the tips there as I can given the window I'm working with.

New questions:
1. Bending the rear axles to achieve cant is a no no right? Better to leave them straight and push in at an angle?
2. How long of a board would work for testing? 4 Foot?
3. How far should it steer over when testing? I've read several threads on this with differing answers.
4. I did pick up some flexible weights at the Scout shop, I was planning to drill holes in the side of the body for weight pockets as this seemed to be the least time consuming method.

 

[Vitamin K]

You can also use bent-axle rears to achieve camber.

I know, I know...this gets me branded as a Commie Mutant Traitor around these parts (props to anybody who gets that reference!), but I had very good results from it with our crop of scout cars this year. I think I'd definitely find it easier than trying to insert into the slots at an angle, or use shims, FWIW.

You can PM me if you want more info on that. /images/boards/smilies/wink.gif

 

[Ironcar]

SNIP

Yeah, that's why I was asking. I know it's not the preferred method from what I've read here, but if it will work for this go around, I might try it.

 

[Chief]

Please do not bend the rear axles...trying to align the car is very difficult!!! If you have a drill press, you can take a 1/8 inch bit and set the block on that and drill into the slots giving you about a 3 degree angle it is not to terribly difficult and it is WAY easier than bent rear axles

 

[3phase]

If you don't live in an area where PWD is full of competitive parents or league racers, just drill your holes straight for your axles (works in the slots too).
Four on the floor will win majority of cub scout races using 5kids wheel and axle prep method.

 

[Vitamin K]

Please do not bend the rear axles...trying to align the car is very difficult!!! If you have a drill press, you can take a 1/8 inch bit and set the block on that and drill into the slots giving you about a 3 degree angle it is not to terribly difficult and it is WAY easier than bent rear axles

Bent axles can be aligned in about 5 minutes if you use a tuning board and a set of bias weights to isolate the wheels. Not to kick off a debate, but I'm not certain how many people are aware of this.

 

[Obsessedderbydad]

Wow, thanks for all the great replies. I spent a bit of time on the 5 kids site yesterday and I plan to incorporate as many of the tips there as I can given the window I'm working with.

New questions:
1. Bending the rear axles to achieve cant is a no no right? Better to leave them straight and push in at an angle?
2. How long of a board would work for testing? 4 Foot?
3. How far should it steer over when testing? I've read several threads on this with differing answers.
4. I did pick up some flexible weights at the Scout shop, I was planning to drill holes in the side of the body for weight pockets as this seemed to be the least time consuming method.

I already answered this in my first response.

 

[Obsessedderbydad]

Please do not bend the rear axles...trying to align the car is very difficult!!! If you have a drill press, you can take a 1/8 inch bit and set the block on that and drill into the slots giving you about a 3 degree angle it is not to terribly difficult and it is WAY easier than bent rear axles

Bent axles can be aligned in about 5 minutes if you use a tuning board and a set of bias weights to isolate the wheels. Not to kick off a debate, but I'm not certain how many people are aware of this.

first off... No!

Second off... NO!

Third... he has 4 days...

 

[ngyoung]

Just doing the axle and wheel prep will give you a huge boost over most scouts. Alignment is important but can be left for whatever time you have left after finishing the axles, wheels, and body if you are using the slots.

I wouldn't start bending the rear axles unless you are trying to correct an alignment issue. There is often an inherent bend in BSA axles that you can use to make minor adjustments.

Aim for 4"over 4'.

 

[dpatrick911]

I am new here but I have to side with a few of the poster that recommended bending the axles. I don't know what kinds of problems you guys had bending axles. But it is a pretty foolproof method for achieving neutral toe on the rear wheels. Granted there is some risk involved with messing up that beautiful polish job you just put on your axles. But in all honesty, his son is 6 years old. He will likely be happy if his car makes it down the track. This is about a dad that has 4 days to build a car with minimal tools to do so that wants to try the "rail riding" technique. We bent rear axles for years and managed to put some hardware on the shelf for my kids. I am not saying it is the best method or even required to win a scout race with reasonable competition. The guy said he is interested in learning. He has 4 days. Buying a Silver Bullet may not even be on the radar for him. He might not even have access to a drill press. I don't know. But given his timing, and what he would like to try, "Rail riding". Bending axles and understanding tuning and the importance of neutral toe on the rears is more important than just drilling them perfect. Learning why it is important is of more value to him than nailing it this year but not getting it right next year and wondering what happened. the bent axle method in my opinion is a super easy way to learn about the canted hole method and why precision is so important. He does not have the luxury of scraping the block and starting over. From the sounds of things he does not even have paint on the car. COM is of far more importance than whether he is drilling canted holes or bending his axles. You have to crawl before you can walk. By bending the axles, he will learn so much about tuning a car that when he decides to drill canted holes he won't be back on here asking what happened and why his car did so poorly at the races. You guys have to admit, there is some intrinsic value in learning about the benefits of neutral toe and in my opinion bent axles will give him that experience without causing him a bunch of unneeded stress with the race being only 4 days away. Just my 2 cents. Feel free to torch me or whatever you want. Having been there and done that. I learned so much from bent rear axles drilling canted holes is the only way I want to run now.

 

[Obsessedderbydad]

I will not support someone bending their rear axles. You can make the car ride the rail without canting the rears. Even if he doesnt bend them or drill a cant, he can still make a fast scout car. With 4 days before the race, you're trying to give this dad so much information on how to make a scout car fast, then telling him to bend the rear axles, THEN he has to figure out how to tune them. Absolutely not. I agree you do have to crawl before you walk, but we're hear to teach people how to walk, not watch them crawl, then throw a method out there where they can stand up, take a step and fall back down. People are going to throw out everything in the world to make this guys car fast. The FACT is there's things he can do and things he cant right now. Bending the rear axles would be a no from me. Do the other steps and you'll still have a fast scout car.

 

[Crash Enburn]

As you can see, some things stir up passion here...

Wow, thanks for all the great replies. I spent a bit of time on the 5 kids site yesterday and I plan to incorporate as many of the tips there as I can given the window I'm working with.

New questions:
1. Bending the rear axles to achieve cant is a no no right? Better to leave them straight and push in at an angle?
Barring having a drill press, a #44 bit, and the ability to repeat the same angle, I will side with ODD and recommend straight axles, inserted as straight and evenly as you can in the rears.
2. How long of a board would work for testing? 4 Foot?
4' is great. I have a 4' long mirror I use.
3. How far should it steer over when testing? I've read several threads on this with differing answers.
4" of steer over 4' is pretty much the standard.
4. I did pick up some flexible weights at the Scout shop, I was planning to drill holes in the side of the body for weight pockets as this seemed to be the least time consuming method.
That sounds like it should work.

Just one more thing regarding weight placement: Not only do you want the weights as far back in the car as you can, but *lower* in the car is better.

 

[Kinser Racing]

I have to tell you please don't bend your rear axles. If you relatively new here, know that we don't recommend or practice that. Its to difficult to get them accurate and tune
. You'll spend d more time with the car than you need to and you can be slower than with straight axles. Maybe you got luck and won bending rears, but you just got lucky. I could build a car with straight axles and beat a bent rear axle car all other things being equal. Please do not recommend it here. WD practice giving the best and most accurate advice on building a fast car and we prove it on the track. If you want speed listen to expedience. The best way is straight axles drilled at a can't. Second to it is straight axles.

 

[Mr Chips Racing]

I admonish you to listen to Kinser. Happy that I taught that boy everthing he knows.