Caster and Camber Change During Turning

[articdragon192]

So, I've been looking over some of my pictures of my Z drifting and I see this:






Heavy camber gain/loss at full lock. It became more apparent after I increased the steering angle with the tie rod end spacers. Now, under normal road racing circumstances, the camber gain is good. Outside tire gains more camber, inside tire loses camber, to flatten out while cornering, for more grip.

But while drifting, it has the opposite effect. At full lock, the camber change almost seems to jack up one corner of the car, and I'm riding on the shoulder of the tire on the leading wheel, as shown in the first pic. And the trailing tire almost run entirely on the inside tread.

I know caster has a major effect on this, but is there any other way to reduce this effect so much? For reference, stock caster specs for a Z are around 9.5-10.5. And I'm running about -3.4 static camber. Running that much camber to compensate for the camber lose of the leasing wheel. However, I see S-chassis cars having this same effect. I'm also kind of fond of how the steering self centers with so much caster dialed in. Counter steering is very quick. However, I mainly just want to flatten out the car a bit more and stop riding on the edges of my tires so much.

[Marcus]

this is unavoidable, due to the amount of caster.
run more negative camber. i run -4*.

btw, keep in mind that this problem gets worse with modded knuckles. ive seen people scrape their wheel lips on the ground because of this.

[articdragon192]

We'll see how tire temps do in this upcoming grip event, and see if adding more camber will still be beneficial. I figure a thicker front sway will help with the car lean, but that means I'll have to get a thicker rear as well. And I'm not much for messing with sway bar. Ugh... maybe I should relocate the mounting brackets for the upper control arms to reduce caster.

[Firestorm]

well, it doesn't look like your car "leans" that much anyway.

a thicker front sway will only make the car understeer, except maybe if you reduce static camber a little.

besides, on a corner, the OUTSIDE wheel is supposed to lose camber, the inside wheel gains camber. but i guess you know that, you just mixed it up.

the only way your tires would sit more square on the road on turning is to reduce caster.
i've observed the same phenomenon on newer mercedes C-class or e-class cars as well. but those are cars that arent supposed to go around corners on full lock, so it's not an issue.

[SoSideways]

Yeah with that much caster, the only thing you can do is dial in more negative camber to counter the effects of the massive amount of caster your car has.

[WISH ONE]

Unless you want to start hacking up pick up points its seems like the only thing you could do is reduce the amount of caster you are running, or run more -static camber which really doesnt help your straight traction or braking for a grip set up . Take into consideration that when you reduce the amount of caster your caster trail will go away also and you will not have as much of that quick counter steer. How much caster are running over stock if any at all?

[articdragon192]

Originally Posted by Firestorm

well, it doesn't look like your car "leans" that much anyway.

a thicker front sway will only make the car understeer, except maybe if you reduce static camber a little.

besides, on a corner, the OUTSIDE wheel is supposed to lose camber, the inside wheel gains camber. but i guess you know that, you just mixed it up.

the only way your tires would sit more square on the road on turning is to reduce caster.
i've observed the same phenomenon on newer mercedes C-class or e-class cars as well. but those are cars that arent supposed to go around corners on full lock, so it's not an issue.

I'm pretty sure I didn't mix it up. My inside tire loses camber and outside tire gains camber.

Originally Posted by WISH ONE

Unless you want to start hacking up pick up points its seems like the only thing you could do is reduce the amount of caster you are running, or run more -static camber which really doesnt help your straight traction or braking for a grip set up . Take into consideration that when you reduce the amount of caster your caster trail will go away also and you will not have as much of that quick counter steer. How much caster are running over stock if any at all?

I'm running in the 9.5 range, stock range.

[!Zar!]

Camber/caster go hand in hand. If you don't want a lot of camber gain then you have to give it less caster.

It returns to center so easily since it has a lot of caster.

I'm confused at what we are getting at exactly.

[SoSideways]

Originally Posted by !Zar!

Camber/caster go hand in hand. If you don't want a lot of camber gain then you have to give it less caster.

It returns to center so easily since it has a lot of caster.

I'm confused at what we are getting at exactly.

I think Arcticdragon is wanting his cake and eating it too, in that he wants less caster for less of the camber gain/loss at full lock situation, but he wants to retain the self-centering effect of running lots of caster

[rioredstang]

The angle you are looking at is steering axis inclination(SAI). This angle creates a jacking effect on the wheels. I haven't studied these front ends to see how to reduce this angle. We try to keep this down on road cars because it will effect corner weights at high angles.

[articdragon192]

I'm assuming that's tthe same as king pin inclination?

[rioredstang]

What problems does this cause for you, or is this something you have noticed. In a drift the rear is in slide or I think they call it yaw angle. Do you need more front grip? Its only a problem if the car wants to push or slide the front tires. You can lower the camber and caster to slow this angle. You also need to watch how much ackerman steering the spindles have.

[PoorMans180SX]

Increasing your static negative camber isn't going to help all that much. You have to think of the arc that the hub goes through during turning, which is determined by the upper and lower ball joints on a Z32.

What you're really going to have to do to mess with this is move the top of the knuckle in, or the bottom of the knuckle out (without moving the ball joints). You really can't do anything without messing with the knuckles.

This will give you more negative camber without gaining more caster, and will change your steering axis inclination, keeping the loaded wheel more upright when sliding, which should give you better front traction.

Now your unloaded wheel will gain even more camber, so there's always a tradeoff.

It will also decrease your wheel clearance up top.

Basically it's going to take some measuring and some fabrication if you really want to mess with it. It's a lot easier to do on a McPherson setup.