What is Camber

[ajg1030]

Ok you guys pretty much described camber. There is positive camber (top of the tire leaning away from the car) and negative camber (top of the tire leaing towards the car). The contact patch is the area of rubber that actually touches the ground.
So lets get real technical and you guys can scratch your heads for a while.

First positive camber on a race car is always BAD. Too much negative camber is also bad. So why?

First let me help you understand what happens to the tire on the race track. When the car enters a corner the ouside front enters BUMP. The suspension move up and the ouside tire moves down, REBOUND.
When this happens the angle that the tire is in relation to the track changes. The contact patch deforms under load due to the slip angle causing side thrust as the contact patch tries to resist deformation.
The tire angle changes in bump towards a positive angle and the ouside tire in REBOUND goes more negative.

Since we want to maintain as much flat area on the track during cornering and the outside front takes the lion share of the load in cornering it is important to never let the tire fall over into a positive camber position.
When you get to a positive camber the tire will tend to go turn toward the outside of the track caused by the change in geometry of the tire angle. so you can go from a compliant car to a while outside steer. I dont know how you like to race your car, but if I did that in my F2000 I might rip a corner off when I leave the track. (Can you say bad weekend!!)
the inside tire is important but I wont get into the details here since it can become mind blowing the first time around.

Now, the second factor when determining negative camber is too much is bad too. Why? Well the more camber you have the on the wheels creates less contact patch in a straight line. So the car will have reduced breaking capability. This isn't a problem if your one of those straight line guys but in road racing, the less time you spend in the braking zone is more time you can spend on the throttle, so a faster lap time.

There are a few good books out there on this stuff. Carrol Smith writes a few. Also you can read some posts from a guy called richard pare on f2000.com. This is a formula 2000 race site for guys that race pretty much everyweek in the US. Sorry mod no ad intended, just another avenue for people to get real answers from real racers.

[Guest]

the best static camber setting is of course influenced by the tyre ,radials allowing more Camber than Diagonals for example.Also a car running lots of downforce will not like much static camber as the loads at high speed will push the car down a lot inducing too much camber.
The cambergains by the geometry of the car combined with the setup (stiff with not much wheelmovements or soft with lots of wheel travel)
will all influenc your static camber considerations as well as the track itself.If you got a crowned road surface (as any public road has for draining the rain...) you always want less camber of course,but at the end of the day track performance/stopwatch as well as safety will decide just how much camber you have to put on the car.You will surely go for the maximum contact patch on the whole lap.

[Guest]

Reading this thread makes me think that no one has considered (or knows ) the actual reason why almost all cars, and everything rolls the direction it does. If we take a road car, or even an F1 car, we know that the car 'rolls' so that the outside suspension compresses, and the inside suspension extends.
The reason this motion is achieved is that the car's Centre of Gravity is above its Roll Centre.
If you look at the car from the front or back, you can put 2 dots vertically above each other (ideally), in the horizontal middle. The lower dot is the Roll Centre, and the higher dot is the Centre of Gravity.

Now it gets more complicated. The closer these 2 dots are, in vertical relation to each other, the less the car will roll. It is at this point that we can relate to 'lowering the centre of gravity' which we continuously hear from engine designers etc.

Essentially, you can imagine that the 'lateral force' * pushing the car outwards is acting horizontally on the centre of gravity point. If this point is above the roll centre (which it invariably is) then the car is seen to roll.

If we imagine a very unlikely situation, which i've never seen - only imagined, for a minute. What if the Centre of Gravity point is below the Roll Centre point? Then the car will lean into the corner!!!
I don't know whether i've explained it enough for people to visualize but i think that sounds right.

Back to normal situations with cars, another factor to take into account is that the suspension can be setup so that as it compresses, the camber changes. Usually, the camber becomes 'more positive' as the suspension compresses.

* I know that the centrepetal force acts toward the pivot of the circle (ie. the apex of the corner) and is provided by the friction from tyres, but it is much easier to talk about there being a force acting 'outwards'. lol

sorry for the long post, just keep thinking about relevant (i hope ) information.

rob

[Stas]

Camber is a tilting af a wheel from its centerline.
Caster is a relationship of shocck absorber to its control arm.
TOE is a inward or uotwart movement of a wheel.
Those 3 are the most important things in suspension setup..
Camber cause very bad tire wear and toe cause feathering on a tyry. Also its hard to steer cars with positiv caster.

[RacingManiac]

too much right now in this thread is emphasizing on the actual relation to the tire to the road to the reason why we run negative camber, a huge fact is how actually a tire work with camber thrust. With the tire leans inward towards the car, from the tire construction and so forth it generates a inward force pushing towards the center of car. This force varies with vertical load on that tire. That force is called camber thrust. You want to run negative camber so that on the outside tire, where their normal load increases, that they still can generate a certain amount of camber thrust in cornering, which adds to the overall cornering grip of the car. Obviously though camber thrust and the actual contact size are has to be balanced. Generally you dont go higher than 4 degrees of camber, but again this depends on what your tire data looks like and how much camber thrust it generate.

This is also the reason why, in F1 or most racing nowadays, when a car don't really roll that much anymore, you still would run negative camber. And couple with a very stiff roll bar. With more anti-roll, you promote more lateral weight transfer, away from inside tire, where their camber is in the wrong direction, and their camber thrust will fight against what you want it....

[ferrarist]

Do you mean camber of the wheel, or camber of a wing section???

Will be interesting to know something about wing camber?
I didnt read more about that....

[Guest]

camber means angle basicly......................so wing angle

[Monstrobolaxa]

camber means angle basicly......................so wing angle

Well actually you're wrong Guest......

Well when you have a airfoil you have the leading edge and trailing edge....the straight line that connects these 2 is called the CHORD.

Going from the leading edge to the trailing edge you have another line that connects both....but in this case instead of being straight it's curved...and is the average distance from the upper surface of the wing and the lower surface of the wing....this is called the CAMBER LINE (or mean line).

The distance between the chord line and the camber line is the camber of the wing (at the determined point)

The maximum distance between the chord line and the camber line is the maximum camber.

[ferrarist]

Perfect....thanks

[ReubenG]

Can some one elaborate on camber thrust and how the tyre construction leads to lateral forces?

[Guest]

Just to add another variable to the camber discussion. We have thoroughly discussed how camber changes with suspension bump + rebound in cornering, and how camber changes with roll in cornering as well.

Something for those of you who are learning that you can further research is the effect CASTER has on camber during STEERING, which i don't think has been discussed yet.

The amount of caster present in the setup of the suspension can cause camber changes that can help/hurt your cornering performance when the car is steered. When the tires are steered, camber changes occur and often times you can design the suspension so that more negative camber is gained in the outside (heavily loaded tire) as the tires are steered, this can offset some of the body roll effects which tend to cause a positive camber gain on the outside tire. Again this depends on if you want more negative camber or not. The key is to realize that body roll, suspension travel, and STEERING all affect camber, and each of these parameters has to be taken into account when designing a suspension.

The thing to remember about all this camber discussion is that each suspension setup is CAR specific, and perhaps more importantly TIRE specific. You can't really make a generalization for what is a good camber angle and what is not, it all has to be designed in conjunction with tire data and the specific application (racing, general automotive use, whatever).

Great thread

[DaveKillens]

x

[Reca]

AFAIK the effect of camber on rolling resistance is an increment, anyway it’s quantitatively a little effect, smaller than what you have with toe.

I wonder is that inside edge manufactured from a harder compound just to give a very low rolling resistance in a straight line?

Rules require homogeneous compound.

[RacingManiac]

As Carroll Smith stated in Tune to Win, negative camber would actually increase the tire's coefficient of friction, which would in effect also increase its rolling resisitance....