Thanks
I noticed exactly the same thing: it seems short! It's odd though... It's narrower than your usual 2WD (it's 240-242mm-ish), has a narrower chassis than your usual buggy and in fact with a 280mm wheelbase it's considerably longer than most wheelbase buggies come with as standard (though that recently shifted to +8mm for many cars). At 280mm it is 6mm shorter than the old one, and it may be part of the floaty rear end, but I think not the main cause.
I think it's this: With the weight balance and weight I measured the car has only 270 grams resting on the rear end when standing still
Any increase and decrease of weight (=axle load) that happens on the rear end has a big effect on the percentage of grip on the rear end,even if the absolute weight shift is small. Off-power (=drag brake, 4%) and under braking this counts even more so because the braking removes even more axle load.
At that point any imperfection in the surface will make a huge difference for the stability. The smallest nudge will make it lose grip too far and slide because there is no weight to generate grip. Once you lose grip there is very little the car can do to activate it again because again there isn't any weight to play with.
All I need to do is make sure there is just enough axle load on the rear end under braking to keep the car from sliding to a point where you can't keep your racing line
First thing here is to make it race legal. I have to add almost 15% of the current weight to the car. Let's assume that under braking the rear wheels also have 15% more weight to play with whatever was there under braking before... That could be the difference between spinning out and touching the apex like a pro. If that doesn't make enough of a difference I have a nice set of variables to play with:
- Use rear tires with more bite.
- Add more rear camber.
- Add more rear toe-in.
- Play with the ground clearance between front and rear.
- Use heavier front springs and damping (something that the car might need anyway).
- Add pack on the front (something it most definetely needs).
- Add droop to the rear (this I think should help particularly on bumpy surfaces, not to cure the rear bite issue itself alltogether).
- Add rear 'anti-squat' (spacers under rear suspension blocks).
- Add downforce on the rear end (after all downforce gradually goes down with the speed, it doesn't suddenly shift forward like the weight balance).
- Adjust the squat/kickup on the front.
- Increase the wheelbase (a realistic option as the car seems to have plenty of agility and the sliding has a bigger effect (and danger) at high speeds, but like I stated earlier on it's own maybe not enough).
I 'just' have to find out which of these variables makes the best difference
Adding axle load is a thing that will happen just by making the car race legal... But reducing how much of that the rear end loses under braking is at least as interesting, as that mainly affects the car under braking (where the front end doesn't need that extra axle load from a shifting weight balance).
By the way, I'm just reminding myself... this was the first test with the car! I just threw a setup on there based on theories. I'm really happy with where the car stands with the first setup, with some adjustments I'm confident the car will have the immense steering and acceleration capabilities with a planted rear end.