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txchemist

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Reply with quote  #1 

 

I want to be able to let a Cub do the tuning on the car himself.

The normal bent DFW axle and screwdriver adjustment is difficult for some adults, and super hard for a Cub.

 

The Plug & Play is perfect for Cubs, but I want to do the next step up without  going all the way to a Pro bent axle setup. When you might run on a poor track and jump off at the stop, you want the most rugged design, and that is the straight axle with drift built in. The approach I use is to drill a 4 on the floor canted car. Back two wheels canted away from the rail, front two wheels canted toward the rails, and it runs straight- no drift. I can get this most of the time, but a Cub gets it off a tad from time to time. I have one Pack that has very strict 4 on the floor rules where they roll the car on a mirror, and all 4 must roll. I also have other Packs with different kids that have loose rules and of course we will run a 3 -wheeler rail runner. So we start with a try at a 4 on the floor, and then cut the car in half just behind the front wheels. We then use either a few thin rubber bands or one big band to hold the car back together { small wood blocks added to adjust tension so wood does not move without some effort} on a simple wood jig.  The jig allows a slight twist of the front wheels to get 4 on the floor very simply. It also has a hex-nut height adjustment to lower or raise the slope of the bottom of the car, and last of all you can add a few strips of newspaper to get the drift you want by testing on your tuning table.

 

 

Too make a 3- wheeler, just add the wedge under the NDFW and that rotates the front of the car to increase the set angle of the DFW, and decreases the angle of the NDFW as it lifts that wheel. It was noticed that with a 4 on the floor, only two strips of paper were needed to make the correct drift because with both front wheels touching and steering,  not much extra offset to straight was needed.  When the car was twisted into a 3- wheeler with the wedge, it then took 6 strips of paper to get correct drift.

 

 

Now the last adjustment you can make is to push the entire front of the car to the side so that the DFW just hits the rail, and then carefully lift off and re-test drift on your tuning table and go back and forth if you need to until you get it all the way you want. The typical Cub gets all this and quickly understands how we are adjusting the car, but he will not normally see that putting drift and rail running is faster than 4 on the floor straight. You can quickly go back and forth and show on a track if you have one.  If not, you just have to say- trust me, and show a few NPWDRL videos where the car with big wiggles is out of the running..

 

 

So you can now shave off how much wood is needed to get a perfect  spacing on the NDFW  [ on the right] to the rail, and cut it off of just the front of the car. Leave the DFW side alone. If you mess up, it will not be a big thing to adjust the NDFW spacing over and over.

Now  the best way to glue the rough body back together is something like marine epoxy with a 30 minute working time, or PC-7 which gives you a full hour to re-position and test drift and test on the track where you can change all kinds of things in an hour, and let it sit of 24 hours and you have a pre-tuned block to shape back into the 7 in. limit if needed, and smooth the bottom and sides to remove any sharp edges without messing up the area near the axle holes.

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ngyoung

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Reply with quote  #2 
Having an access hole on the bottom to grab the axle with a needle nose to turn it is a little more kid friendly in my opinion.  When they're done just tape over it with a piece of clear packing tape.  

Your jig setup is nuts so you will likely think of something more clever then what I suggested.

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B_Regal Racing

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Reply with quote  #3 
My kid is a cub and he was able to adjust drift with a good k-house groove cut and minimal bend on the FDW without any problem at all.  We gave a small seminar with my kid actually doing the demonstration showing the differences in times.  I found that scouts could adjust cars with 3 degree bends in the FDW, but they could not "dial it in" with anything more than a 1 degree bend.  It can be done with a normal car.  We also demonstrated weight placement and the effect it has on speed using this car:

[COG_Car_zps4e2251f9] 

The weight can easily be screwed in with little hands and no tools.

With a properly setup drill press, he is also able to drill his own axles holes.  The problem I have was not what a scout can do, but more of holding their attention for 30 minutes of more.

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laserman

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Reply with quote  #4 
Hi TX,

Wow!  That is cool!

A very visual way of explaining to the cub the different adjustments.

My nephew ran on a really rough track last year and I expect the same for next year.


I had not considered the durability of the car.  There was a no fenders rule which seemed ridiculous.

Here was the stop section


Is the straight axle preferred in such a situation to prevent a twist on the DFW, which would in turn mess up the steer?

Thanks
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txchemist

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Reply with quote  #5 
Laserman- Thanks, Yes if the bent axle is loose enough to turn easy, it gets knocked out of alignment easy. If you have a straight axle - it is way better. I guess you could epoxy or super glue the axle in place, but part of the goal is to teach, and the concept of a bent axle with rotation is not as simple as turning your handlebars to steer your bike or adding paper to one side to steer the car.

Also, that 30 min. attention span should be part of a well thought out schedule. If they can commit to lots of sessions and they love it, you can teach a lot and make a super car. If they do not have the enthusiasm, have simple cars in mind to fit the attention span. Some boys and there Dads come over a few times even in the summer and work on next years car. I have some older Scouts who bring their little Cub brother over and help make a car and they make a full pro- type car to race in the adults division.
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B_Regal Racing

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Reply with quote  #6 
Keep us posted how it works out, and if you would change anything.  I will be doing something in September /  October time frame and would be very curious to know what, if anything, you would change. 
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