I’ve done some more mucking about with the digital model of my Spit’s modified rear suspension design and it’s really rather interesting. I thought it might help though if I related it to how it actually effects the handling though. Here’s what I’ve found (bear with me on this).
Here’s what it looks like static (-1 degree of static camber).
On bump, it gains a moderate amount of negative camber.
On droop, it gains a smaller amount of positive camber.
So far so good. However, when subjected to roll, the loaded wheel (on the right) gains positive camber. This is not so great for cornering.
However, it’s only during a sweeping corner (and a fleeting moment in tighter corners) that you get roll in isolation. For the rear suspension on corner entry it’s accompanied by droop, and on corner exit it’s accompanied by bump.
Combining droop and roll basically combines the two effects, meaning for me I get more positive camber, which is not so good of a thing.
A similar combination happens for bump, where for me I gain less positive camber, which is a good thing.
So, what does all of this mean?
The easiest way is to describe the process of accelerating towards a corner from a standstill, braking and then going through the corner, roughly comparing my suspension design to another chap who’s very cleverly made a suspension design that remains at ~0.75 degrees of negative camber throughout the suspension travel.
So, we both nail it at the start. The rear ends of both cars squat down. His car gets more traction off the line due to the fact that his wheels stay more level with the surface of the road (-0.75 deg vs -2.3 deg).
Approaching the corner at full tilt, we both slam on the brakes. At this point, I can’t quite work out whose will be more stable. Mine transitions through neutral camber to slightly positive at full droop. His remains static at -0.75 degrees the whole way through. I want to say mine will end up with more grip overall so better braking from the rears, but I’m not certain if camber thrust will mean his is more stable throughout than mine which ends up twitchier. Lets call it a dead heat.
Entering the corner, we both tip it in. The rear end is still up in the air from braking, and the car starts to roll. Mine is definitely twitchier and has less overall grip at this point. The positive camber from droop combines with the positive camber from roll and the rear end starts to slip and slide a little. His rear end is a little more planted as his consistent negative camber on droop works to combat the positive camber from roll, allowing him to carry more speed through the turn.
Mid-corner, both cars level out in a steady state of roll. Here, mine starts to claw back some speed. Although it’s not really modelled above, my design winds up with less positive camber gain during roll. The roles are reversed and his rear wheels start to slip slightly.
Exiting the corner, we both plant it. Both cars squat again, but are still in a state of roll. Here, his car tends to positive as his slight negative camber isn’t enough to offset the positive camber from rolling. He’s forced to countersteer as he comes out of the corner slightly sideways, scrubbing speed for the straight ahead. My more aggressive camber curve does offset the positive camber from roll and I put the power down nicely for a good clean corner exit.
Who winds up ahead at the end of that I have no idea, but hopefully that makes a little sense for how all of these camber curves actually affect real-world driving dynamics :)