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Old 09-12-2003, 12:28 PM   #16
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Negative camber is necessary because when a car turn into a corner, it experiences chassis roll, which increases the tires' camber angle. Also, because most rubber tires are quite flexible, they get a little deformed in the direction of the center of the corner. If the car doesn't have any negative camber, only the tires' outer edge and sidewall would touch the ground, which isn't beneficial for traction. A tire's coefficient of traction (grip) increases as it's contact surface increases, so the ideal situation would be that the tire would stay perpendicular to the ground at all times, and that it wouldn't deform under heavy side load. Unfortunately, this isn't the case; most of the time you have to find the best compromise. The problem is that if you want maximum forward traction, you have to set the camber to 0, and if you want maximum cornering action you have to set it to a few degrees negative, depending on the softness of the suspension and tire carcass.
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Old 09-12-2003, 01:42 PM   #17
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You should go back and read my original post...
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Old 09-12-2003, 02:07 PM   #18
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Default Confused about Camber! (kinda long)

As the Car leans in a corner, the suspension will cause the outside Tires/Wheels to go Positive in Camber and lose traction.

What you are trying to do with a static negative Camber setting, is compensate for this tendency and keep the Tires as flat as possible during corning for maximum grip.

Last edited by popsracer; 09-12-2003 at 02:12 PM.
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Old 09-12-2003, 02:31 PM   #19
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Yes thanks.. I understand teh concept as I explained in my original post, but that doesn't happen. Compressed suspension on my car causes the camber to go more positive, with the tires turned, totally leaned and pushed to the outside. And its not just a little, it will go from -1 to -2 or -3. The whole car is basically set to the books recomendations, which looks pretty neutral. I HAVE been running my car at -1, but in looking at my tire wear, 99% of the tire wear is right on the inside track of the tire, right by the inner sidewall....

So SOMETHING isn't right....
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Old 09-12-2003, 02:39 PM   #20
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Dude, i think your major problem is the suspension of the Schumacher. I ran a Mission for a while, and it seemed to me to have a lot of camber change. This was a while ago though. Maybe i can get Kevin K over here. He ran Schumachers for a long time, and he had a handle on the camber change thing. I do remember tires coning a lot...
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Old 09-12-2003, 02:49 PM   #21
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Quote:
Originally posted by robk
Dude, i think your major problem is the suspension of the Schumacher.
how do you figure? the mission is a top notch car engineered by some of the best in the business... its not the car, it HAS to be setup.
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Old 09-12-2003, 03:24 PM   #22
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You have two problems there.
The tyre wear you're talking about is a common problem with Take Off's newer insirts, they have too much air gap and cause a rim to form on the inside of the tyre.

As for the camber not doing what you think it should, you're trying to simulate what happens in a corner in the wrong way. The force put on the car doesn't come from anything on top or to the side of the chassis pushing on it. It comes from the friction between the tyres and the road surface. Hold a wheel in the middle and push it to the outside, the wheel will try to lean over, much like it does when racing, and this will turn your camber into zero camber if you have the perfect setup, the rest of the chassis and suspension moves around this, not the wheel moving around what the chassis/suspension does like in your simulation.

hope that makes sense
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Old 09-12-2003, 03:58 PM   #23
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hhmm..
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Old 09-12-2003, 04:10 PM   #24
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Quote:
Originally posted by Herminator
You have two problems there.
The tyre wear you're talking about is a common problem with Take Off's newer insirts, they have too much air gap and cause a rim to form on the inside of the tyre.

As for the camber not doing what you think it should, you're trying to simulate what happens in a corner in the wrong way. The force put on the car doesn't come from anything on top or to the side of the chassis pushing on it. It comes from the friction between the tyres and the road surface. Hold a wheel in the middle and push it to the outside, the wheel will try to lean over, much like it does when racing, and this will turn your camber into zero camber if you have the perfect setup, the rest of the chassis and suspension moves around this, not the wheel moving around what the chassis/suspension does like in your simulation.

hope that makes sense
I agree totally,
You can make adjustments on your set up board but you can in no way accurately simulate the forces etc that are applied to the tyre under running conditions. The best way is to make the adjustment via the set up board and take it to the track and see the effect.

steevo
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Old 09-12-2003, 07:07 PM   #25
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Im no expert with touring cars but I dont think at any time you want to gain positive castor as the suspension is compressed.
That just isnt the way a front end is supposed to work.
I would guess there are geometry problems with your front end.
Either link location or something weird.
Ive never seen a mission up close but I bet something is assembled wrong or parts are reversed somewhere.
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Old 09-12-2003, 08:42 PM   #26
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The Herminator is right. What you are describing is two 'problems'. Firstly, the grove in the tyre is a thing with the Take Offs running the standard insert, but I believe it's because the insert is too narrow. Although, that insert does give superior grip... and they still last a long time. You can sacrifice a bit of grip, but get rid of the groove by running different inserts, like Sorex medium c's.

Now, about your suspension. You are gaining camber as you turn the wheels because of the castor. That is the whole purpose of castor. You can run the camber close to zero for better braking and traction in acceletation (when there is no lateral loading on the tyre), and then as you crank in the steering angle, the camber increases so that once the chassis rolls and the rim and tyre deform a little, you will have a nice, big contact patch. The reason Camber increases as you push down on the car (hitting a bump) is becase of the lengths and geometry of the linkages. Again, it is designed into the suspension, because as your car rolls into a corner, the outside of it squats down. This is especially helpful at the back where ther is no steering movement and castor to induce the negative camber required for the corner.
By using the in-line option on your hubs you will decrease this camber gain.

Now, to simulate what is happening in the corner for real, this time really think about what is happening. As you approch the corner you lift off the throttle, so the front will squat a little and the rear will rise. This should give you a fraction more camer at the front, and a little less at the rear. Now, as you have a little camber dialed in at the front, it will be willing to turn sharply (depending on your toe settins, which is a whole other thing). So as you feed in the steering the chassis will roll onto the outside tyres, a little more to the ouside front. But not just that, you will see the inside front tyre go to POSITIVE camber, this is a good thing, as it will try to dig into the track, and is being dragged across the track in a digging in motion, not a sliding accross motion. Look at your car as you read this, and it will become clear. Now you're at the apex, and begin to feed in throttle, and decrease the steering angle. Wieght and squat shifts to the rear, cambers move accordingly, and you're back on the staight, heading for the next turn.

Please keep in mind during all of this that your chassis ROLLS over and tries to lift the inside tyres off the ground, so simulate that with your setup station. How quickly your chissis rolls is a function of your shock absorbers and roll centre. The maximum angle of roll you achieve is a function of your springs, roll bars and roll centre (and of course the wieght distribution in the car).

And finally, you have two smart options when setting your camber angles. You can set them to get maximum wear and life from your tyres, which is fine. You will frequently find that a little extra negative camber will provide you with more grip, even if only slight, but decrease the longevity of the tyres. The choice is yours!

Last edited by BagofSkill; 09-12-2003 at 08:49 PM.
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Old 09-12-2003, 08:57 PM   #27
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Quote:
Originally posted by Steevo
I agree totally,
You can make adjustments on your set up board but you can in no way simulate the forces etc that are applied to the tyre under running conditions. The best way is to make the adjustment via the set up board and take it to the track and see the effect.

steevo
I third that notion. You can use the set up board to measure the angles etc but you can't simulate what the car does while running on the track no matter how much one may think he understands about weight transfer under braking, cornering etc. In full scale racing the mechanics make the changes based on their knowledge of how suspension geometry works and then the driver puts the laps in to test the result. If any changes are needed they are made and the car is track tested again.

I think this is the only way of seeing if you have the best set up for the conditions..
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Old 09-13-2003, 03:42 AM   #28
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I agree with BagofSkill and pretty much everyone else. Just pushing down on the suspension will naturally increase the negative camber on both tires. But in a turn, the inside raises up as the outer compresses (hense chassis roll). So, when you are "simulating" a turn, make sure you "twist" the chassis. There you should see the tire stand up closer to 0* camber.

Again, not an acurate depiction of the forces in a turn, but more so than just pushing down on the suspension.
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Old 09-13-2003, 04:17 PM   #29
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Default Take-Off Tires/Inserts

Guys;

Too soft of an insert will cause the "Grooving" that many People are seeing with the Take-Off Pre-mounts. Solution is to Mount your own with firmer inserts and/or less air gap.

I have always believed in using the Firmest insert that the Car set-up will except and still have decent traction.

BTW, I personally use the TO Pre-mounts myself. I get enough runs out of them to not worry about the grooving.
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Old 09-13-2003, 10:18 PM   #30
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camber is not so much about angles and rolling,but more about creating a larger contact patch on the tyres(as explained by many a poster on this thread) but i feel the need to reinforce this point.
simple maths:say contact area when wheels are perpendicular(upright) is A
then at -2 deg's camber,new contact area would be A/(cosine 2deg's)
cosine2 is less than 1,meaning new contact area is MORE THAN A.

Of course,u would ask why negative camber?the same equation above applies for +camber...
Now this is when rolling,sliding comes into play.at negative camber,the friction from the tyres can be separated into 2 perpendicular components,namely 1-downward(from deadweight of car) and 2-sideways,towards the car.Now this component keeps the car from sliding and also rolling(when this force is multiplied with the perpendicular distance from the roll center).the sideways component of friction force doesn't exist at 0 camber or positve camber,hence negative.

U would be wondering,wow then i want plenty of negative camber.this is not feasible when u factor in the uneven tyre wear and the fact that sometimes u want the car to slide a little for more cornering action.Cars in F1 have plenty of front camber,almost 0 rear camber bcos of this.

hope this helps,and do correct me if i'm wrong.
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