I do think a balanced arm gives a significant performance boost, both theoretically (energy is used more efficiently) and in practice (my P3 is quicker).
So there is an issue for those that have them (established racers) and those that don't (newbies). One thing that got me hooked on HO was I could race from day one with a car that was on the pace (even if I wasn't) and hopping up a SG+ for Nascar was quite simple and not expensive.
I'm not sure the economics are as simple as in the opening post.
If you're just racing one chassis, then - yes - you just need one arm. Until if goes off or you wreck it. Jon has already said that the HC arms go off quite quickly. The Wizzard SP05 balanced 3-Ohm arm has a reputation for burning up if you're not careful...
If it's an expensive ($50+) arm you
would take very good care of it and it makes economic sense to send it back to Wizzard, Slottech etc to be reconditioned at the end of the season.
If balanced arms became standard in club racing, then I run:
Mega-G in EAHORC F1 (plus I want to build a spare)
Tyco in WHO F1 (and my current EAHORC spare)
Wizzard P3 in EAHORC pro-mod (I have 2 cars)
Mega-G in WHO Mod (plus a 1.5 as spare)
Tomy SG+ in WHO Nascar (and a spare EAHORC car if Pro doesn't run)
So that's potentially eight cars I would need a balanced arm for. Quite an outlay, even on a $10-$25-an-arm basis.
For the box stock cars, I am running the arms that came with the cars - and I've done okay with them.
My WHO Mod Mega-G is my original EAHORC F1 car, with the same arm. At HONK I'll have one Pro-mod P3 with an HC balanced arm and one with a stock Mattel arm. By MBR or NSR, I hope to have balances arms in both cars.
I accept that some people will buy up hundreds of cars to find the best stock arm. But they still need to build a decent car and drive it well.
I agree with Rich that this is a bigger issue with the older pancake cars, when most NOS arms available are
[email protected] That's why using at least the internals of the JL and AW cars is not a bad idea. RC at Dynamic Armatures is also a possibility, but not exactly a cheap option. Maybe someone in the UK can start offering a balancing service? Martech maybe?
Overall, I think it's only in pro-mod that the balanced arm comes into play - at the moment.