breakdown

I've been searching the forums a lot, reading about alignment, handling etc and one thing I come across all the time is negative camber and how it helps with handling on the track. Why exactly is this the case?

Preeble

In a turn, your outer tires bear the brunt of the handling responsibility and they will tend to roll out/away from the car - this reduces the contact patch of the tire. The negative camber (which points the top of the wheel/tire into the car and the bottom edge away from the car) allows for a greater contact patch in these turns as the tire will roll into the patch.

For pictures and a better description, search for camber on wikipedia.

brendo

zackly

And depending on how you use your car, you'll adjust the camber. if you track it and scream up the roads to the mountains all the time, you'll want more camber, as you won't care as much about the setting wearing out your tires when you're mostly not corning hard in daily driving...

sjfehr

Suspension on cars are designed to accommodate rough road surfaces, and to press the tire into the road under as many conditions as possible; this is built into the geometry. Imagine a car traveling in a straight line with tires of 0 camber. When one wheels hits a 1" bump, the suspension will ideally deflect exactly 1" while keeping the tire's surface parallel to the ground so that it still maintains grip.

Imagine now, the same situation, only with body roll and weight transfer in a corner- to the suspension, it's very similar to hitting a bump, except now since the whole car is rolling, NONE of the tires are flat to the ground.

Real-life suspension geometry is a compromise between these two. Porsche mac struts gain a little negative camber when they deflect- more than ideal for straight line, but less than idea for handling. On such a setup, 0 camber is best for tire wear, but loses grip in corners. A few degrees of negative camber increase grip in corners, but wear more quickly on the inside during regular road driving. Most late-model Porsches do both at stock alignments: a few degrees of camber on wide tires at optimal pressure in the rear to maximize rear grip, and 0 camber on underinflated (at porsche pressure spec!) narrow tires in front so that at the limit of traction, the front wheels will lose grip first and the cars get nice-safe-boring-but-predictable understeer.

Stiffer springs help, as they reduce body roll. As do stiffer anti-roll bars and stiffer shocks. But only up to a certain point; too stiff, and it can actually make things worse, and the suspension becomes unable to deflect enough to keep the wheels planted and every bump becomes a tiny ramp, launching the car over the surface. All these factors need to be balanced properly, and the car tuned to the particular driver's preferences.

-----
You might also wonder... why do wide tires grip better than narrow? But that's a much longer and more complicated answer involving slip angles and dynamic coefficients of friction.

BlueJay73

Just for fun, you can ask somebody about camber settings on a motorcycle...

Marshal_Mercer

Not an issue of camber, which is variable on a bike, but until fairly recently, belt-drive Harley-Davidsons were built with their front and rear wheels out of alignment. That made for some interesting "handling".

Here's something else to ponder: with a car, steer left, go left; with a bike, steer left, go right. It's all in the tires' slip angle.

utkinpol

that is kinda good link about this:
http://www.miracerros.com/mustang/t_suspension.htm

AYHSMB

BTW it's a big mistake for street drivers to copy the cool track kids and run lots of negative camber. It's easy to get carried away with the internet crowds' idea of the "right" settings.

breakdown

Is there an optimal amount of negative camber for aggressive driving in the canyons? I think I remember reading that the stock C2S suspension can have around -1.5 degrees of camber dialed in. Would this help driving dynamics on the twisty roads without compromising too much on the street?

zanwar

-1.5 is about as far as you want to go for street driving, although there's more to alignment than negative camber. If you have an aggressive street alignment that includes -1.0 degrees of camber you'll feel a difference in the handling but the negative effects will be manageable. There will be some bump steer and the car will be more eager to rotate. All good things for aggressive driving on a familiar track but you'll need to pay attention on the street.

utkinpol

stock c2s suspension allows max of -1 deg of camber in front. to get more than that you need to replace lower control arms and put in adjustable ones from gt3 car. no one needs more than -1 deg for street driving.
i personally do not like how car handles when you get more camber in rear than in front so i would say - set up -1 deg in front and same -1 deg in rear, then reduce front toe to 0.05 fron what is was stock and set 0.10 toe in rear. that shold reduce rear tire wear a lot and make car more 'alive'.

for track people set front toe to 0. on a street it will result with steering wheel reacting to each and every bump - and most people do not like it, so, there is no reason to do it. castor is not adjustable on stock suspension neither and is not important for street driving.

sjfehr

There's no single value that's optimal for every condition. It depends on the weight (option package) of your car, driver/passenger/cargo weight, stiffness/settings of springs, shocks and swaybar, the tires you're using, and even the road surface and condition. Skidpad is a good way to measure grip and trial/error until you maximize it, but the best way to quickly determine optimal camber is to drive aggressively, and use a pyrometer to adjust camber until the temperatures are even across the tire.