I’m building a 1/4” ladder car for my son running a 5 3/4” wheelbase which is weighing 10 grams right now. We’ll likely run 4” in 4’ of steer. We will run 2 ounces of tungsten (12 cubes) in the far rear. Right now the balance point is right at 1/2” in front of the rear axle with 2 ounces on each side of the axle. My question is will the car be stable (& not wheelie) if I put 2 more ounces right in front of the rear axle or should I slide some cube in front of rear axle forward to increase the balance point? If so how far in front of the rear axle should the balance point be for a Cub Scout race on a 42’ aluminum track? We ran 3.04-3.06 (on average) on a non ladder car with graphite & no fenders last year with a balance point of 7/8” & 2” of steer in 4’. Just trying to get faster.
Take this with a grain of salt as I am not a pro. However, I will share what I have learned over the last 8 months.
When trying to compare one car to another and asking oneself if it will be faster, a number of items need to be considered.
How stable did last years car run? What axles & wheels were on it. What wheel/bore prep was done? What "improvements" am I trying to make?
To answer your question ...it will not wheelie, but will it run straight? It depends. How good is your foundation (drill)? Is your alignment near perfect? What wheels and prep will be used? Remember that wheel bore to axle slop along with excess wheel gap can contribute to a car that wiggles.
What you have going for you is the long WB is normally quite stable and will track straighter. A true .500" COM is quite aggressive for a scout car. What I have read here is that something around .625" - .700" is a good COM for a scout car. That along with a WB around 5" seems to be the consensus that I have read.
While having the COM as far back as possible has the most potential to have a fast car, I believe that giving up a bit on the COM is not a bad thing. paying CLOSE attention to ALL of the other details (specifically the wheel/bore prep & Drill) will yield the best results.
Again, this is just my humble opinion.
You have come to the correct place to learn and get answers ...Good Luck.