Caster settings, Explain please Options

[r_towle]

How does the caster setting affect an AutoX car.

What is the best, and why.

Rich

[jhadler]

I'm pretty firmly in the camp of caster is good for autox. And more is better. Granted, there's such a thing as too much of a good thing. But the dynamic camber gain more than makes up for the reduced turn-in if that is the ONLY thing you're doing.

But it's all a system. Caster alone is not the end-all-be-all. You need to dial the rest of the car in around it. And a truly hot setup for autox, is not going to be a hot setup for track or street.

Having a lot of caster allows you to run less static negative camber, giving you a better contact patch for braking. Turn-in won't be as light, but the car will have more front end grip when you need it (mid turn). Turn-in then can be played with by toe, or spring rate, or just compensating with the steering nut. I think I'd rather have a little more effort for turn-in if it meant I could carry an extra .15 G around a turn.

-Josh2

[woobn8r]

I'm pretty firmly in the camp of caster is good for autox. And more is better. Granted, there's such a thing as too much of a good thing. But the dynamic camber gain more than makes up for the reduced turn-in if that is the ONLY thing you're doing.

But it's all a system. Caster alone is not the end-all-be-all. You need to dial the rest of the car in around it. And a truly hot setup for autox, is not going to be a hot setup for track or street.

Having a lot of caster allows you to run less static negative camber, giving you a better contact patch for braking. Turn-in won't be as light, but the car will have more front end grip when you need it (mid turn). Turn-in then can be played with by toe, or spring rate, or just compensating with the steering nut. I think I'd rather have a little more effort for turn-in if it meant I could carry an extra .15 G around a turn.

-Josh2

You had me right up to the point where you say you set up with less negative camber and have more grip in a corner....not in my experience...but I also don't run max caster on my race cars...I do use a pyrometer to maximize all test set ups though....I'm also not sure your more caster/less neg camber theory is correct...but if it works for you...who am I to argue.

[jhadler]

You had me right up to the point where you say you set up with less negative camber and have more grip in a corner....not in my experience...but I also don't run max caster on my race cars...I do use a pyrometer to maximize all test set ups though....I'm also not sure your more caster/less neg camber theory is correct...but if it works for you...who am I to argue.

Absolutely. The pyrometer tells all. With more caster, you don't need radical amounts of static negative camber. The negative camber grows as the wheel is turned. Now, a track car doesn't see as much steering angle as an autox car does, and as such, you don't get as much of a camber benefit from caster.

For a fictional example: You have a 1982 hupmobile.

You can, fictionally speaking, come off a hypothetical skidpad with identical tire temps. Two different setups.

Car 1: 6 degrees of caster, -1.5 degrees of camber.
Car 2: 4 degrees of casetr, -3 degrees of camber.

Car 2 will have lighter, more responsive turn-in, but will be more prone to locking up a tire under braking, and if there are a lot of high speed straights, the inner edge will wear more.

Car 1 will have heavier turn-in, but will have more contact patch on the ground when the wheel is straight.

What's good on the track, is not necessarily good for autox, and vice versa.

-Josh2