Are you using too much camber (>1.5)? real RUF has bigger rear camber too

sucahyo

In GT2 car with 11/11 spring rate have half body roll of 2/2 spring rate. And car with 20/20 spring rate usually have very small (<0.5) or no body roll.
I am curious why everyone seem to use camber more than 2.0 when they use stiff spring rate. In GT2 if your camber is too big (6.0) the tire will have less traction on corner, and in straight line it will reduce tire traction significantly (1 second slower at 1000m test). I don't know if PD change it in GT4, making the tire have more traction in corner and straight when using bigger camber.

It seem to me everyone believe that front camber have to be double of rear camber even though some car have the rear body roll greater than the front (wagon or RR or car with long rear overhang). Maybe everyone use it because they prefer understeer car.

in GT4 it seems 12.0 equal to 12º
I am using this picture (taken by scaff), measured about 12º

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Team666

The reason I´m using a larger camber in the front is just traction! the car in my scenario is rear wheel drive, so the propelling wheels get a smaller camber to increase acceleration grip, and the larger camber in the front makes it possible to brake deeper into a turn.

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sucahyo

I see.
I think camber should be smaller when we use stiffer spring rate or lower ride height. Do you reduce the camber when you use stiffer spring rate or you use general camber setting?
How do you know you have too much camber?
From what you told I think you usually use spring rate bellow 10, correct?

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sucahyo

On some university paper I read that car with heavier front tend to have smaller overall body roll compare to car with heavier rear. So FF car or FR with front bias weight distribution should have low body roll. But I only confirmed it in GT2, I don't know if it work in GT4 too.

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Team666

Explain why camber should be smaller in those cases, please.

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    spring   height   damper    tire  front anrear ang  RCD
    2.0/2.0  160/160   10/10    N/N     4.4     5.3      45
   2.0/20.0  160/160   10/10    N/N     2.2     1.2      65
   20.0/2.0  160/160   10/10    N/N     1.2     0.8      60
   20.0/20.0 160/160   10/10    N/N     0.6     0.0     100
    2.0/2.0  160/108   10/10    N/N     3.5     3.3      51
    2.0/2.0  108/160   10/10    N/N     2.8     3.0      48
    2.0/2.0  108/108   10/10    N/N     1.2     1.8      40

Team666

I use a springrate somwhere between 6 and 12, depending on car and track.

I´m pretty sure this applies for GT4 as well. And I usually end up with a slightly higher camber in MR cars (0.2-0.4).

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Vision GT

haha you just haven't seen my MAXED OUT camber FD in GT3

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sucahyo

How much ?

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www.tiretech.com

Camber

The camber angle identifies how far the tire slants away from vertical when viewed directly from the front or back of the vehicle. Camber is expressed in degrees, and is said to be negative when the top of the tire tilts inward toward the center of the vehicle and positive when the top leans away from the center of the vehicle.

Since street suspensions cannot completely compensate for the outer tire tipping towards the outside when the vehicle leansin a corner, there isn't a magical camber setting that will allow the tires to remain vertical when traveling straight down the road (for more even wear), and remain perpendicular to the road during hard cornering (for more generous grip).

Different driving styles can also influence the desired camber angle as well. An enthusiastic driver who corners faster than a reserved driver will receive more cornering grip and longer tire life from a tire aligned with more negative camber. However with the aggressive negative camber, a reserved driver's lower cornering speeds would cause the inside edges of the tires to wear faster than the outside edges.

What's the downside to negative camber? Negative camber leans both tires on the axle towards the center of the vehicle. Each tire develops an equal and offsetting "camber thrust" force (the same principle that causes a motorcycle to turn when it leans) even when the vehicle is driven straight ahead. If the vehicle encounters a bump that only causes one tire to lose some of its grip, the other tire's negative camber will push the vehicle in the direction of the tire that lost grip. The vehicle may feel more "nervous" and become more susceptible to tramlining. Excessive camber will also reduce the available straight-line grip required for rapid acceleration and hard stops.

Appropriate camber settings that take into account the vehicle and driver's aggressiveness will help balance treadwear with cornering performance. For street-driven vehicles, this means that tire wear and handling requirements must be balanced according to the driver's needs. The goal is to use enough negative camber to provide good cornering performance while not requiring the tire to put too much of its load on the inner edge while traveling in a straight line. Less negative camber (until the tire is perpendicular to the road at zero camber) typically will reduce the cornering ability, but results in more even wear.

Even though they have some of the most refined suspensions in the world, the next time you see a head-on photo of a Formula 1 car or CART Champ Car set up for a road course, notice how much negative camber is dialed into the front wheels. While this is certainly an example of wear not being as important as grip, negative camber even helps these sophisticated racing cars corner better.

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Scaff

BTW - The picture of my Clio V6 (blue one) used to show camber is in fact a shot taken before I tuned the car and so actually has zero camber set.

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niclake13

Just to see if I'm following this correctly... for a car like the BMW M3, I probably don't need too much camber in it, due to the overall good handling/looseness of the car already... am I following this right?

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GEETOWN_DRIFTER

i like to use about 2.3front, 2.0 rear, that works for me. but on some i'll go all the way 7.0 with it,it doesnt help for driftin but it looks kool while ur doin it...lol

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http://www.ybapublications.co.uk/shortcircuit/Features/sc_story_testing.htm

The two main points about oval track handling are turn-in and Corner speed, turn-in can normally only be evaluated by driver feel and corner speed by a stopwatch.
Start by setting up the camber and tyre pressure with the aid of a tyre pyrometer, they can be bought for around £100 if you can't borrow one, maybe not cheap, but what did you pay for the car?
Temperatures should be taken at the inner edge, the outer edge and the centre, as soon as possible after the car has stopped. The inner and outer edges should be the same when the camber is correct, too much negative camber will make the inner edge warmer and too much positive the outer edge is warmer, for tyre pressure the centre should be the same as the average of the inner and outer edges, (but then you've already set the camber and got them the same, right?).
Although if the outer edge is warmer you could also reduce body roll. After arriving at a setting for tyre pressures and camber you can now start to play with the turn-in, drivers vary on what they like so this one is pretty much up to you! To alter this you use tracking settings (toe in and out) or change the relative roll stiffness between front and rear, but remember only change one thing at once. If possible it is better to change antiroll bars than springs or the car may not work on a bumpy track, and don't forget, changing the angle of roll alters the camber, so you'll need to check this again! As I said there's a lot of variables in suspension technology!
As a guide, to make the car understeer less stiffen the rear or soften the front or a reversal to reduce oversteer. The limit to roll stiffness is when the car starts to lift a wheel, then you have car too far and will have to look at other methods, you cannot tune the suspension of your now 3 wheeled car.
Tracking adjustments are another way of altering turn-in, increasing toe-in will give understeer and toe-out will give oversteer. While you can make a car f better by adding camber or reducing tyre pressures it is at the expense of total grip levels and should not be done except maybe as a last resort to fine tune, if all else has failed.
If you have adjustable shockers, all you can really do is play and see what feels right, but start from soft, and gradually increase until it feels right and do one end at a time.
If the car is heavy in a turn you can reduce caster, but be careful as too little can make the car very unstable in a straight, obviously on a short tight track this will have little importance though.
As a rough guide: to reduce understeer; increase weight transfer at rear by increasing rear roll stiffness, reduce weight transfer at front by reducing front roll stiffness, reduce toe-in, use wider front tyres, increase front tyre pressure (a last resort only).
To reduce oversteer; reduce weight transfer at rear reducing rear roll stiffness, increase weight transfer front by increasing front roll stiffness, increase toe in, use wider rear tyres, increase rear tyre pressure (a last resort only)
The car feels as good as you can get it, you want to go on and thrash everyone in the next race right? Wrong the next step is simply to drive it faster and start again, there's no conclusion to this one, as the handling gets better you just increase the driving speed, see which end is losing grip first and start again, it just becomes harder to improve and you gain less, but it's always possible improve it!

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http://www.442.com/oldsfaq/ofsus.htm

Put the front end of your A-body up on jackstands. Now that the wheels are at full droop, note how the tops of the tires lean in towards each other (lots of negative camber). Now put a jack under one lower control arm and slowly jack it upwards. Watch the tyre/wheel as you do this, you will see the tire go from leaning inwards at the top all the way to leaning outwards at the top as you jack the control arm up through its range of travel. That change prevents the tire from staying flat on the road and gripping with all its tread width - this is an extreme example of camber change with suspension travel and it is not good suspension geometry, it is absolutely horrible suspension geometry! On any well-engineered suspension this camber change should be undetectable by eye, it takes a camber gauge to measure it on any of the Mopar's I've owned, for instance.

An even quicker and easier way to see the poor camber curve on the GM A-bodies is to get a buddy to drive one over a speed-bump and watch the camber angle on the wheel/tire as it goes over the bump. This is how I first noticed how bad the geometry is! You can see the tops of the tires lean outwards as the speed bump pushes the suspension up into the wheelwells.

When you go into a turn with a GM A-body the outside front tire does more of the work than any of the other three tires (the weight transfers to the outer two tires, so the inner two are lightly loaded and don't do much work; also these cars carry more than half their weight on the front wheels so it is the outside front tire that provides a majority of the grip needed to make the turn) and this is the very tire that is being tipped over by the camber change, reducing its grip at the very moment it is being asked to provide all it can. To get maximum lateral grip the tire MUST be flat on the road or have very slight negative camber, and that is the reason for all the interest in re-engineering the front suspension on these cars using taller spindles, etc.

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Car                    front   rear
===================================
Kei Office S14 roll    3.3     2.4
Kei Office S14 camber  2.8     2.5
Altezza roll           2.3     1.2
NSX roll               3.6
Porsche GT3? roll      1.9     2.8
Supra roll             3.6     3.3

sucahyo

I see. Interesting, you start from zero camber too . And 1.4&#186; is for car front body roll angle, not wheel camber (my description is misleading ).
If the car is untuned, then the body roll should be lower when tuned.

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sucahyo

If you are not sure, try to measure the angle of your car when turning (you can zoom it in photomode?). If it measure less than 1 degree, you won't miss the cornering traction much if you use zero camber. We use low camber not because the car is handling good, but because the car has low body roll.
In GT2 using zero camber is better than using 0.5 camber.
GT2 BMW 328Ci measured as:
3.0&#186; front, less than 1.0&#186; rear on 2/2 spring rate 150/150 ride height
1.1&#186; front, less than 1.0&#186; rear on 8/8 spring rate 110/110 ride height

Japanese drifter earlier use it too to make the rear slide easier on low power car, they call it demon camber (mentioned in FR Drift Guide - By Boundary Layer and Swift). But I am not sure how much they use it.

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sucahyo

This is a nice explanation on how we set up camber in real life. This is reference that make me believe that camber should be the set according to the amount of body roll. It also say to use camber only if all else fail, so, I start my tuning with zero camber.

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The two main points about oval track handling.....

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sucahyo

And this is the reference that make me believe camber shouldn't be bigger than body roll angle. That is, to make the tire make flat contact to the road, a 1.2 degree body roll should have 1.2 degree camber max.

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Scaff

The zero camber starting point does very much depend on the car in question, sometimes I do and sometimes I start with the default setting.

In regard to body roll being lower when tuned, that does of course depend on the default settings and the track being tuned for. In the case of the Clio V6, as I was tuning for Deep Forest I actually reduced both the damper and spring rates for the car. As the default settings are too firm for my driving style and this track in addition to minimal changes to the ride height, as a result tuning in this case incresed body roll.

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Scaff

An excellent starting point, but I still personally find that a degree of trial and error is required in fine-tuning camber settings.

Don't get me wrong, what you have outlined here is an excellent starting point, but it is just that, a starting point.

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sucahyo

I see.

Yes, I hope more people will start put more attention to camber.
I mean, It's a pity if you have the tool to see how much your car roll in every corner with great detail (photo mode), and not use it to tune your car. And too many of you ignore the fact that RUF have more rear roll than front (I can be wrong, but it is true in GT2 and BMI drift video). And please aware that there are other car beside RUF that have heavier rear.
People tend to use 2.0/1.0 for RUF camber, which is questionable. Too many people rate this car as understeer, and yet people make it more understeer with worng camber value. The one who don't use very oversteer suspension setting. If they decide to use camber, they should atleast using slightly bigger rear.

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sucahyo

For front wheel, there is caster. I don't know GT engine implement caster or not, wether they the same for every car or not. But this is what I think:
- at front wheel 0 degree turning, the amount the wheel angle to the road is the same as the car roll.
- at front wheel 90 degree turning, the amount the wheel angle to the road is the same as the car pitch plus caster angle.
- at front wheel 1 to 89 degree turning, the amount the wheel angle to the road is between the above.

About the camber angle, yes, even on GT2 using 2.0 for rear for RR car using 8/8 spring rate would be too much. Using 2.5 for front is excessive for RR car.

About camber angle for car with heavier rear, from what I test:
- FR car have front roll about 3x to 0.5x rear roll
- FF car have front roll about 2x rear roll
- MR car have front roll about 1.5x to 0.5x rear roll
My conclusion:
- car which have front roll 1.5x rear roll have perfect distribution
- car which have front roll more than 1.5x rear roll have heavier front
- car which have front roll less than 1.5x rear roll have heavier rear

Only some car have more rear roll and should need higher rear camber (4 out of 29 car I test).

About higher rear camber for RR car, I got some picture of real life porsche car, some of them use higher rear camber. So, why don't we copy them?

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Scaff

Good stuff (once again) and as I said at the end of my last post, if it works use it. But as you have shown, so use higher rear camber others don't., so you still have to set it up for the car and driver.

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Team666

You also has to consider what track you are running at, especially the surface. If it´s very bumby, á la Nürburgring, too much camber may send the car somewhat sideways even when driving in a straight line. Camber is always a compromize between straightline stability and corner stability. Just like toe.

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Leonidae

sunny.. I always do a base setup that has 3.0' camber front and 1.5-2.0' rear, and start adjusting the suspension from there towards better one..💡

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