DFW bent axel

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drward

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Mar 19, 2014
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Gentlemen,

I have been studying here for about a year but never posted before. My son and I are building 2 cars for our upcoming pack derby, one for him and one for me. We are building rail riders according to DD4H’s guidelines (thanks). Our district requires 4 wheels touching and no grooved axels. We made our DFW axels from the instructions on 5 kids web site (thanks). Do you all know of anyone ever being accused of running grooved axels because they notched them for bending? I know the intent is to eliminate the advantage for people with more money or better tools/skill but has this ever been used to DQ someone? Maybe I’m over thinking this. Tell me if you think that is the case. I can take it. Thank you in advance for any responses.
 
It would be pretty hard for someone to argue that you grooved an axle to remove friction with you are putting a groove to bend the axle. Totally different.
 
I haven't heard of such a thing, but that does not mean that they can't "gotcha!" on the technicality.

You can bend your axle using a hammer and screwdriver/chisel. I use my "axle straightening block" to hold the axle, then tap at the appropriate location with the hammer/screwdriver combo. I also use the "asb" as a holder for my axle and as a guide for cutting the K-House groove into the head of the DFW axle (before bending).
 
The BSA axles are soft enough to bend without a groove if you're worried. The groove will pretty much be seated in the body once installed anyway and is unlikely to be noticed either way.
 
Crash Enburn said:
I haven't heard of such a thing, but that does not mean that they can't "gotcha!" on the technicality.

You can bend your axle using a hammer and screwdriver/chisel. I use my "axle straightening block" to hold the axle, then tap at the appropriate location with the hammer/screwdriver combo. I also use the "asb" as a holder for my axle and as a guide for cutting the K-House groove into the head of the DFW axle (before bending).
Click to expand...

If they can gotcha for cutting a groove in the axle then they can gotcha for a k house groove.
 
Thanks so much for the feed back. We are running 2 bent axels on front per DD4H to get 4 on the floor. We have 2 made with groove. We'll do the other 2 without. Our rules state you can build more than one car so we are building ours together and son gets the one that turns out the best. If we get a chance to advance beyond pack I will put the grooved axels in the fastest car. Thanks again for all the help, all of you.
 
Thanks to this site and all your input we won our pack derby and we are going to our district meet this Saturday!!!

If I may trouble you all one more time, should I re-burnish the wheels as reprep or just add graphite? Wheel bores were prepped, per 5 kids site, with Novus 2 polish and burnished with DD4H zero friction graphite.

Now an observation. We built both cars identical with the exception of wheel placement and direction of steer. Car #1 had stock wheel base shifted rearward. This allowed only 1.2 oz of weight (lead shot) behind rear axel and COM of 7/8". Car #2 had wheels in stock location, 1.8oz behind rear axel, and COM of 5/8". Car #2 was consistently 1/2 car length faster but they were the 2 fastest cars there.
 
Congratulations!
cool
clap

drward said:
If I may trouble you all one more time, should I re-burnish the wheels as reprep or just add graphite?
Click to expand...
No need to reburnish or do anything else for reprep other than add in more graphite. When you snap your finger on a wheel (with the car upside-down), the wheel should spin >20s. As long as you're hitting that kind of number, you're good to go.

drward said:
We built both cars identical with the exception of wheel placement and direction of steer. Car #1 had stock wheel base shifted rearward. This allowed only 1.2 oz of weight (lead shot) behind rear axel and COM of 7/8". Car #2 had wheels in stock location, 1.8oz behind rear axel, and COM of 5/8". Car #2 was consistently 1/2 car length faster
Click to expand...
drward said:
We have 2 [bent axles] made with groove.
Click to expand...

So, did you wind up grooving the second pair of axles, so both cars were running grooved? If not, which car got the grooved axles?

As to one being consistently faster than the other, there are a bunch of variables that aren't necessarily accounted for (how much steering, vertical location of CoM, aero, etc.), so it's tough to say. It seems, though, that both cars wound up with the CoM the same distance from the front of the car, so that element can be eliminated.

Good luck on Saturday!
 
Thanks Crash,

The car we are going to run has the axels with the groove at the bend. The other set were bent without a groove by clamping in a vise and tapping with a small wood dowel and hammer. Both were polished with the DD4H kit. We are going to swap them out because we want to avoid any controversy. I know this "groove" has nothing to do with axels grooved to reduce friction but you know how emotional people get when their kids (losing) are involved. I want to avoid any hint of cheating.

Thanks for the advice. I will just add graphite and spin them.
 
Just an update for all those who helped us so much. District derby was Saturday morning. My son averaged 3.186, good for third place, over 9 runs on a 3 lane aluminum “Fast Track”. This is the only track we have ever run on besides the old wooden one at our pack derby. It seemed a little rough to me. Cars would sometimes jump when they hit the joints. Still everyone was on the same track so had the same opportunity. We brought home a plaque which made him happy, which in turn made me happy.

Thanks again, all of you, for making this possible.

p.s. I got the silver bullet, carbide bit, axel polishing kit, and zero friction graphite from DD4H this year. What do you think is the next biggest bang for the buck? I’m thinking tungsten cubes so I can make the body thinner.
 
drward said:
Just an update for all those who helped us so much. District derby was Saturday morning. My son averaged 3.186, good for third place, over 9 runs on a 3 lane aluminum “Fast Track”. This is the only track we have ever run on besides the old wooden one at our pack derby. It seemed a little rough to me. Cars would sometimes jump when they hit the joints. Still everyone was on the same track so had the same opportunity. We brought home a plaque which made him happy, which in turn made me happy.

Thanks again, all of you, for making this possible.

p.s. I got the silver bullet, carbide bit, axel polishing kit, and zero friction graphite from DD4H this year. What do you think is the next biggest bang for the buck? I’m thinking tungsten cubes so I can make the body thinner.
Click to expand...

Congrats to your son! When you walk away happy, you're a winner!

In my amateur opinion, as long as you're getting your COM to a reasonable place (5/8" - 3/4" or so), you don't necessarily need tungsten. You might want to look into bore prep tools/materials, since there's a lot of speed to be gained there.
 
drward said:
Just an update for all those who helped us so much. District derby was Saturday morning. My son averaged 3.186, good for third place, over 9 runs on a 3 lane aluminum “Fast Track”. This is the only track we have ever run on besides the old wooden one at our pack derby. It seemed a little rough to me. Cars would sometimes jump when they hit the joints. Still everyone was on the same track so had the same opportunity. We brought home a plaque which made him happy, which in turn made me happy.

Thanks again, all of you, for making this possible.

p.s. I got the silver bullet, carbide bit, axel polishing kit, and zero friction graphite from DD4H this year. What do you think is the next biggest bang for the buck? I’m thinking tungsten cubes so I can make the body thinner.
Click to expand...

Tungsten is a must, but I must ask, are you buying to build more scout cars or to race in the NPWDRL?
 
As of now, I am just looking ahead to next years scout season. But I must admit I am amazed at the speeds you guys are getting out of these little cars. My wife thinks I have gone too far already but I know my son and I have just scratched the surface. So to answer your question, I won't rule it out. Since we don't have a test track it would be a good way to fin out what our next car can do.
 
OPARENNEN said:
Just my opinion. From an expense standpoint, use 150 dollars as the midpoint. More is competitive, and less is not.
Although BASX might be a bit less, but not much.
Click to expand...

My estimated expenses (just rounded off guesses):

One Time Expenses (assuming you have full access to all the tools that would be found in a regular wood shop):
Axle Prep: $20
Wheel Prep: $30
Silver Bullet: $40
Bits: $15

Each car:
Block: $5
Axles: $15
Wheels: $35 (this one can obviously vary tremendously)
Tungsten: $25
Paint/Covering: $15
Gee Fenders: $30
Prep supply usage: $5
Shipping: $15

So my guess is each car is ~$150 with BASX being ~$110. Assume an ~$100 extra to get started.

Anybody have any idea how much a competitive SR or Unlimited runs? Is there anything I'm missing from my list that the top guys are using? Any special tools besides what I listed to get started?
 
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