i should have listened.

[DNA RACING]

well, against the better advice of John, i am going ahead the most aggressive car i have done to date.
there are 15 cubes behind the rear axle! the com is just about 5/16" when i add the fenders up front i should be looking at a 3/8" com. without weight, the car, wheels, axles and fenders weigh .09 oz. 25 cubes total in it.
have any of you guys built a car similar to this? i am looking for any tips on what to look out for while tuning tomorrow.
i know that i am in for a brutal time trying to keep it straight, but if i can pull it off the payoff should be worth it. actually, all 4 of the new cars have a com under 5/8".
no pics yet, but they should be up tomorrow sometime.

 

[Quicktimederby]

Sounds Like my new SS. You are going to have a lot of fun tuning that thing!! It took me about 2hr. to get mine under control!! And a lot of move the weight around.

 

[W racing]

Coal Car has a COM of 3/8". However the tungsten disc is low and concentrated which helps a bit...

http://forums.derbydad4hire.com/post/CoalCar-5598194

 

[zeebzob]

I just built an unlimited with 17 1/2 cubes behind the rear wheels. It is amazingly stable. But since I built it, its still slow.

 

[W racing]

Hello ZeebZob!!! Good to hear form you!

 

[DNA RACING]

I just built an unlimited with 17 1/2 cubes behind the rear wheels. It is amazingly stable. But since I built it, its still slow.

how did you get 17 1/2 cubes? my SS has 3 rows of 5 and 6 cubes about a half inch in front of the axle.

 

[DNA RACING]

Coal Car has a COM of 3/8". However the tungsten disc is low and concentrated which helps a bit...

http://forums.derbydad4hire.com/post/CoalCar-5598194

all the cubes are flush with the bottom of the car. i have never used a disk before, are they easier than cubes?

 

[Resophonic Racing]

Coal Car has a COM of 3/8". However the tungsten disc is low and concentrated which helps a bit...

http://forums.derbydad4hire.com/post/CoalCar-5598194

all the cubes are flush with the bottom of the car. i have never used a disk before, are they easier than cubes?

Negative side to a disc is once you install there is no adjustment. Also you have to trim the axles almost an 8th to install them in the body.

 

[quadad]

We have built a LOT of cars with tungsten round discs, mostly using the high density 3 oz ones. The disc is easy, since essentially you are preparing the majority of your weight pocket with one clean hole from a forstner bit, etc. Once I even cut a disc in half and placed it around an axle - not worth the effort though !

I have yet to make a league competitive car though with one (but I am sure others have). I agree on the downside - limited flexibility in moving the weight around during tuning. The other downside is the added height, even with the most dense versions. Our best luck was always with standard WB incorporations and I still suggest it to some young Scouts since it's quick to do. I wouldn't expect to see any dominate in an adult league though.

Oh, you should hear that ZeebZob car with the heavy back go down the track - SWEET ! If he can get its times to match its sound he'll have a real winner there.

 

[Old Geeezer]

1/4" or 1/2" cubes?" 17 1/2" cubes is way over weight for tungsten.

 

[DNA RACING]

1/4" or 1/2" cubes?" 17 1/2" cubes is way over weight for tungsten.

he means 17 and one half cubes, not 17 half inch cubes.

 

[zeebzob]

1/4" or 1/2" cubes?"  17 1/2" cubes is way over weight for tungsten.

he means 17 and one half cubes, not 17 half inch cubes.

Correct....I widened the rear to get 7 across 2 rows deep, and I moved the rear axle forward 1/8" and I was able to fit 28 1/8" cubes giving me the equivilant of 17 and a half 1/4" cubes.

 

[Old Geeezer]

Thanks for the clarification, thought maybe you guys were talking new math.....lol

 

[DNA RACING]

1/4" or 1/2" cubes?" 17 1/2" cubes is way over weight for tungsten.

he means 17 and one half cubes, not 17 half inch cubes.

Correct....I widened the rear to get 7 across 2 rows deep, and I moved the rear axle forward 1/8" and I was able to fit 28 1/8" cubes giving me the equivilant of 17 and a half 1/4" cubes.

got any pics of that? i was thinking of using those to fine tune the weight.