Fenders

[Travis H Smith]

Hello, I can run 3 wheels with extending wheel base. I also have a CNC machine that I can use in this process. I've been making prototypes and wondering if this is giving me an edge or am I wasting my time. I am using balsa wood for the fenders and I am planning on skinning the body as well with balsa wood. I use pewter for weights, I melt it down and use a scale to get it where I want it. The notches on the side are for the fender placement. I also can use bent nails as well which I run 2.5 degrees in the back and 1 degree in front rail ride and will add a guide pin too. I plan on skinning the inside of the wheels as well. I hollow out the fenders to reduce the weight and will skin that part to close it up. The pic of the fenders before sanding and will make it more aerodynamic once its cut. Should I go down the path of the fenders or am I making the fenders too complicated?

 

[B_Regal Racing]

I think you are making fenders more complicated than it is. If you are using balsa for fenders, they will be light enough after final shaping. I believe there is little to be gained hollowing a balsa fender, but a lot to lose should the fender break. The weight savings is insignificant. As far as the notches go for fender alignment, you can simply the process by installing a wheel and with a rubber band around it, and pressing the fender against the wheel. In lieu of a rubber band, you can use thin cardboard, tape, paper, or anything you desire to create a small gap between the wheel and fender when gluing the fender to the car.

As a side note, I would not go above the wheel with a fender. I do believe the extra height will create wind resistance.

But it looks like you have some mad skillz with a CNC machine...

 

[Travis H Smith]

Thanks for the tip!

 

[Reecedad]

Nice looking work. What are the holes for? I see 3 so I think one is for each wheel but not sure

 

[Travis H Smith]

Yeah the wheels, I'm going to run a guide fin/pin on the left side. This was proto 1, I expanded the wood around the axles I chipped the front. I added this access so I can adjust the axles from the inside or remove them without scratching the nail. I run bent axels so I can easily adjust for rail ride as well. My next one will be a deeper and once I get my fenders close then I will melt pewter and pour into the back cavities. then I will finish off sanding the bottom and skin it with balsa wood. this way I can get it as low and center as I can. Come race day if i'm over then I just shave some of the metal down.

 

[B_Regal Racing]

There has been significant debate over bent axles vs. axles drilled with a canted hole. Save yourself a ton of grief and hours of tuning and drill canted axle holes in the rear. I promise you'll be faster. Get a drill jig from any vendor.

 

[Thinkin'Bout Racin]

There has been significant debate over bent axles vs. axles drilled with a canted hole. Save yourself a ton of grief and hours of tuning and drill canted axle holes in the rear. I promise you'll be faster. Get a drill jig from any vendor.

Take this for what it is worth, because I have only done scout races. Can you build a fast car with bent rear axles ...yes you can. However, I agree with B Regal that you can save a lot of grief and tuning time by drilling the rears canted!

Don't ask how I know, it took a lot of trial and tuning to get a car to run right and be decent. Once I had a good jig, the first car out was SOOOOOO easy to tune and was a bit faster with MUCH, MUCH less work to get it to run right!

The other thing about a jig for drilling is that you can be almost perfectly consistent so that you can focus efforts on what else might be making a car faster/slower without wondering if your "rear axle tune" is the same.

 

[Reecedad]

There has been significant debate over bent axles vs. axles drilled with a canted hole. Save yourself a ton of grief and hours of tuning and drill canted axle holes in the rear. I promise you'll be faster. Get a drill jig from any vendor.

Do racers in the box stock class have to tune each axle individually? Because the axles all seem to come bent I'm considering grooving each axle and try my luck tuning each individually

 

[B_Regal Racing]

With respect to axles, box stock, BASX, and SS are all built the same way, with most racers . Of course, box stock relegates you to using those axles in the kit. For the rears, I would cut a k-house groove in the axle head and rotate each rear axle to get the best possible performance. The axles in the kit are not straight to begin with; you certainly can find speed by rotating them. I would not, however, intentionally bend a rear axle. Rear axles holes being absolutely parallel, absolutely at the same height, and canted are all ingredients for a good rear alignment and a fast car.

I would be curious if other box stockers are cutting grooves. Initially, I myself probably would not groove the axle, only because I would be concerned that I would reduce the diameter of the axle in the polishing process of the cut edge. But, that is an interesting question that I do not have a good answer for. Maybe Superfast or Veterans will chime in. Both have very fast Box Stocks

The k-house groove also allows you to adjust the wheel gap easily and precisely. Twisting an axle will allow you to change the wheel gap with very little pressure (as opposed to pushing straight down on the nail head). With stainless steel axles, wheel gap is extremely important. I would assume the same would hold true for BSA axles.

 

[Reecedad]

With respect to axles, box stock, BASX, and SS are all built the same way, with most racers . Of course, box stock relegates you to using those axles in the kit. For the rears, I would cut a k-house groove in the axle head and rotate each rear axle to get the best possible performance. The axles in the kit are not straight to begin with; you certainly can find speed by rotating them. I would not, however, intentionally bend a rear axle. Rear axles holes being absolutely parallel, absolutely at the same height, and canted are all ingredients for a good rear alignment and a fast car.

I would be curious if other box stockers are cutting grooves. Initially, I myself probably would not groove the axle, only because I would be concerned that I would reduce the diameter of the axle in the polishing process of the cut edge. But, that is an interesting question that I do not have a good answer for. Maybe Superfast or Veterans will chime in. Both have very fast Box Stocks

The k-house groove also allows you to adjust the wheel gap easily and precisely. Twisting an axle will allow you to change the wheel gap with very little pressure (as opposed to pushing straight down on the nail head). With stainless steel axles, wheel gap is extremely important. I would assume the same would hold true for BSA axles.

Thank you for responding. I started to think this might be one of those secret things that people didn't discuss and or comment on.

Since I've only been doing this since March and I have already determined BSA axles are all bent I'd have to assume most pro league racers know the same. The fact I received very little response to my question speaks volumes.

 

[Travis H Smith]

You have me sold on the jig thank you for your input it makes sense as long as you are square. And scaling back on the fenders. I have some redesigning to do!

 

[B_Regal Racing]

You have me sold on the jig thank you for your input it makes sense as long as you are square. And scaling back on the fenders. I have some redesigning to do!

Look at some of the pictures from past races. Its super easy to see what works. When the X3 fender design came out, I was watching to see if it made a difference. I even went so far as to review the racer's past speeds with his new speeds with the X3 fender design. Me, like most racers, began coping that design, only to find similar speed gains.

 

[Travis H Smith]

With the X3 design, should I not extend the wheel base then? If I am looking at the rules correctly they could have extend wheel base right?

 

[B_Regal Racing]

Thank you for responding. I started to think this might be one of those secret things that people didn't discuss and or comment on.

Since I've only been doing this since March and I have already determined BSA axles are all bent I'd have to assume most pro league racers know the same. The fact I received very little response to my question speaks volumes.

Axle prep is not a secret and I really do not believe the pros are unwilling to share their knowledge. I believe it to be more related to the time of season. Right now, most of the scout parents are gone and only the racers remain. We chat but I think most of us work independently or in very small groups. Keep asking questions - the answers will come.

 

[B_Regal Racing]

I run 4 3/4". Most are in that neighborhood, + or - 1/4"

 

[Reecedad]

Axle prep is not a secret and I really do not believe the pros are unwilling to share their knowledge. I believe it to be more related to the time of season. Right now, most of the scout parents are gone and only the racers remain. We chat but I think most of us work independently or in very small groups. Keep asking questions - the answers will come.

Ok-I will do that. Thanks again for responding

 

[Thinkin'Bout Racin]

Reecedad & Travis,

It appears both of you a quite interested in building cars. I would suggest that you consider a precision machinist square and a pair of "1-2-3" blocks be added to you tools boxes. The square has numerous uses and the 1-2-3- blocks can be used to verify that your drill is spot-on. The foundation of the car (alignment) is more important than most people starting out realize. Most have a tendency to focus on wheels and axles. While everything is important to build a complete package, the alignment it CRITICAL!!!

If you polish the axles to 3000 instead of 5,000 or 12,00 and then use polish, you won't be quite as fast. However the difference will be small compared to what happens when your alignment is off.

Wheelbase ...what B- Regal has told you is what I found out also. I might suggest building a 5" w/b first and running that until you are confident that your alignment is spot-on. You can then build different wheelbase cars to see what fits your build style, competence level, and tuning abilities.

I am going to place a disclaimer on what I have told you as I have only built for the scout level and the open class at districts. So take the information that I have shared and use what you can and feel comfortable with. I think most of what I shared can be confirmed by some of the pros here.

One more thing I have found that the BSA axles are bent, but I have had decent luck by sorting thru a dozen or so and getting 4-5 good ones. I have also used the DW axle straightener with some success. I don't follow the directions on how to use it. Rather I do a modified version of their directions. I clean the flashing off first . I then rotate the axle 6 times around its axis and tap lighter. I have found that once I do this, when I chock them up in the drill press that they are quite straight. Remember, if you cut a slot in the head, you can always rotate the axle to fined the best performance.

 

[Reecedad]

Reecedad & Travis,

It appears both of you a quite interested in building cars. I would suggest that you consider a precision machinist square and a pair of "1-2-3" blocks be added to you tools boxes. The square has numerous uses and the 1-2-3- blocks can be used to verify that your drill is spot-on. The foundation of the car (alignment) is more important that most people starting out realize. Most have a tendency to focus on wheels and axles. While everything is important to build a complete package, the alignment it CRITICAL!!!

If you polish the axles to 3000 instead of 5,000 or 12,00 and then use polish, you won't be quite as fast. However the difference will be small compared to what happens when your alignment is off.

Wheelbase ...what B- Regal has told you is what I found out also. I might suggest building a 5" w/b first and running that until you are confident that your alignment is spot-on. You can then build different wheelbase cars to see what fits your build style, competence level, and tuning abilities.

I am going to place a disclaimer on what I have told you as I have only built for the scout level and the open class at districts. So take the information that I have shared and use what you can and feel comfortable with. I think most of what I shared can be confirmed by some of the pros here.

One more thing I have found that the BSA axles are bent, but I have had decent luck by sorting thru a dozen or so and getting 4-5 good ones. I have also use the DW axle straightener with some success. I don't follow the directions on how to use it. Rather I do a modified version of their directions. I clean the flashing off first . I then rotate the axle 6 times around its axis and tap lighter. I have found that one I do this, when I chock them up in the drill press that they are quite straight. Remember, if you cut a slot in the head, you can always rotate the axle to fined the best performance.

Thank you for the help. I have a good machinist square but where can I get the 1-2-3 blocks?

 

[Thinkin'Bout Racin]

Thank you for the help. I have a good machinist square but where can I get the 1-2-3 blocks?

This is just like what I ordered off Amazon. I was pleased with what I got. They have a number of them. I like the ones without the holes.

https://www.amazon.com/BL-123NH-Pai...rd_wg=06ifa&psc=1&refRID=H1WA5FH2CJ8KJM8WFC6X

 

[Travis H Smith]

Where I’m at today almost two months before race day. A few other prototypes have gone by and getting closer to this years design. Im using my CNC to make molds of for my weights. I been using pewter for my weights cheap easy to melt and the kids can handle it without poisoning them. I end up making two part molds with a lip On the car and on the weight I can adjust the weight in the car to make sure I have imy COG where I want. Super glue will hold the weight. Making the molds I am able to weight the car, wheels nails etc. then pour just a little over what I need and clean it up as needed. Using the cnc to make a latter body frame. I made a jig for my jig to hold my body in place so I can drill the holes in place. I am going to use vinyl sticker to wrap the top and bottom of the car. Currently the car wheels nails weight around .7 oz the rest will be pewter. Not sure if I’m going for fenders just yet if time allows I may get some on.