Building first fender car…questions.

[philcav7]

My son and I are building our first fender car. I have some questions if you don’t mind. There’s several. Feel free to answer what you care to.

How critical is the design/shape/installation of fenders? Is it one of those things when done right help and when done wrong hurt you? Obviously rubbing the wheel or rail would be bad. I’ll take efforts to avoid that.

How much clearance to the wheels should there be? I envision putting some junk wheels on with a spacer and using CA glue to install the fender against the shim. Is this the way? What works well for spacing.

I’m running a 3 wheel car and will have 4pc fenders. Front & rear will not be connected. Is this a flawed design?

How pointed/aerodynamic should they be? Should I keep them as tight/streamlined as possible?

Is it okay for the front fender to extend past the nose of the car body?

Is there a target weight I should stay below for fenders?

Anything I should know/words of wisdom that you can share?



Thanks!

 

[Darkside]

Have you watched Bulldog's fender video yet? Good place to start, and may answer a lot of your questions.

My son and I only built one fender car, and we didn't shape the fenders in between the front and rear wheels like Bulldog does in the video. They were just one continuous width and height from wheel to wheel. That seems to be how a lot of the fast guys do them and it was much easier. Of course you still shape the fenders in front of the front wheels to a point, and they should not extend past the nose of the car.

That's about all I know about fenders. Hope it helps.

 

[T-Bone Racing]

Bulldog’s video will explain what you need to know, and it is definitely worth watching.

for a 3 wheeled car, I think the straight fender is the way to go. In Street Pro, most guys run the straight fender on the dominant side, and a traditional, shaped fender on the non dominant side because in the front there is just a guide pin. I’ve built both designs on a 3 wheel car, and the car with the straight fender on the dominant side was faster. Even though there could’ve been other reasons as to why it was faster, I think the design was better.

 

[Prozach2]

Do you want to make the fenders? Buying fenders and gluing them on is a lot easier, and cuts down on the likelihood that your fenders will hurt more than help. I’ve noticed a lot of very bulky/heavy looking fenders at the Cub Scout races that probably hurt more than help b/c they’re putting so much weight towards the front, as opposed to the back, where it should be. I also no a very good racer that lost b/c his fenders were occasionally rubbing the track.

I bought some 3D printed ones from turboderby.com. They use some kind of super lightweight material and worked really well. We placed first in our pack, and were at least two car lengths ahead of the 2nd fastest car.

 

[T-Bone Racing]

Buying fenders isn’t necessarily a bad idea. I first bought plastic fenders for my first few cars, but when I started league racing, I was making so many cars that I wanted to learn how to make them. There is a learning curve to it; one of the first times I tried making fenders it just turned into a pile of cut up balsa. Today, I know how to make them, and t.he only thing I need to buy is the wood (other than tools to make them). However, for scout racing, I’ve found that they’re not necessary. If they are bulky, it makes the net speed even less, which makes them even more worthless. The first time I helped scouts, I gave them plastic fenders, and I quickly saw that it made little to no difference because they were multiple car lengths ahead.

 

[Loud2ns]

I told my kids they only get one year with fenders. I'm not willing to do that much work on their car.

 

[Prozach2]

Buying fenders isn’t necessarily a bad idea. I first bought plastic fenders for my first few cars, but when I started league racing, I was making so many cars that I wanted to learn how to make them. There is a learning curve to it; one of the first times I tried making fenders it just turned into a pile of cut up balsa. Today, I know how to make them, and t.he only thing I need to buy is the wood (other than tools to make them). However, for scout racing, I’ve found that they’re not necessary. If they are bulky, it makes the net speed even less, which makes them even more worthless. The first time I helped scouts, I gave them plastic fenders, and I quickly saw that it made little to no difference because they were multiple car lengths ahead.

Last year, my older son was in his last year of cub scouts and my youngest son wasn’t in cub scouts but was competing in the sibling race. Both builds were virtually identical, but only my older son’s had the plastic fenders. The one with fenders was substantially faster. Now, of course, what happened with two cars isn’t a meaningful sample size, but for what it’s worth, that was my experience.

 

[T-Bone Racing]

I have found the difference in fenders to be anywhere between a .01-.015 speed increase. If that extra bit is needed to win, then building them is beneficial, if not, then it’s typically not worth it, but scouts tend to like the fenders because they look cool.

A great test would be to build a car without fenders, test it, and then tape fenders on the car to see how much it speeds up. I believe Derbydad4hire has a video on doing this test.

 

[Loud2ns]

 

[DerbyDad4Hire]

Fenders have to be done right or they hurt you. The GEE fenders are the best pre made option.