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Caster and Camber in FC for Auto Cross/Circut

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Caster and Camber in FC for Auto Cross/Circut

Old 08-11-02, 04:50 AM
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Caster and Camber in FC for Auto Cross/Circut

Howdy, i am just about to install my camber/caster plates, they are only adjustable on one axis not two, should i install them on an angle so the more camber i run the more caster i also get or should i not worry about adjusting the caster and just set them up to adjust camber only?

What effects have people had changing the caster?

car is a T2 FC

Cheers
Shane
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Old 08-11-02, 08:02 AM
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Where technically for every degree of camber, you need 2degs of caster
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Old 08-11-02, 09:55 AM
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I dunno about that, but I run 2.5 neg cam, 6 pos caster.. The caster is a bit much, the car definitely tells me about it.. Steering wheel is constantly fighting me through corners, and one spin just about broke my finger as the steering wheel spun around But the car feels great!

For an auto-x only car, the 2.5 neg camber is fine, but a street car, the most I'd go is about a degree to 1.5 neg. Caster, 4 is good, 6 is better, but be prepared for the weird feelings driving the car.

PaulC
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Old 08-11-02, 06:54 PM
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I know what camber is. What is caster and what does it do?
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Old 08-12-02, 01:40 AM
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caster is the incline angle (fowards backwards) of the strut, camber being the inwards/outwards.


Paul- is +ve caster forwards?
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Old 08-12-02, 05:55 AM
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positive castor is when the strut tops are leaning back toward the firewall.

on my 1st gen i run 2.5 neg camber and 6 deg pos castor.

i personlly like as much castor as possible as it aids high speed stabilty, though the steering gets heavier with the increase in positive castor too (not easy to park ect..)
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Old 08-12-02, 06:21 AM
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You stated what positive caster does. But what about more neutral caster.
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Old 08-12-02, 10:44 AM
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well with netural caster, you have the easier steering, but you lose the high speed stability of the car. Toe/Caster both depend on what you want to to do. If you have an autox car, you want around -2.5Camber, +6 caster, adn 1/16" toe out in front. if it's a road race car, camber and caster are the same, but then you don't want that toe out since the high speed stability is better with no toe or toe-in
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Old 08-13-02, 01:35 AM
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more caster gives you more turn in, well that has always been the golden rule i have heard
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Old 08-13-02, 01:40 AM
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so should i position my plates to always be at 6 degrees caster, so i can just adjust my camber or should i set them up on an angle so i have 6 degrees caster at the same time i have 2.5 degrees camber and so if i have more camber i also have more caster??/
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Old 08-13-02, 08:40 AM
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Originally posted by HWO
more caster gives you more turn in, well that has always been the golden rule i have heard
Excessive castor can cause a change in the car's balance during cornering. By taking weight off of one front wheel/diagonal you end up with weight transferred to the opposite diagonal.

Rob
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Old 08-13-02, 12:45 PM
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Sorry Rob, but caster has zilch to do with cross weights. You're thinking ride height and coil overs.

More caster gives you a stable car at higher speeds. Less caster gives you a car more willing to turn in at low speeds, but unstable at higher speeds. For turn in, look at 1/16 to 1/8 toe out on the front.

HWO, get camber to 2.5, if you can get caster to 6, good, but if not, don't sweat it. Camber's much more important for tire wear and grip.

PaulC
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Old 08-13-02, 01:44 PM
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Originally posted by Silkworm
Sorry Rob, but caster has zilch to do with cross weights. You're thinking ride height and coil overs.

More caster gives you a stable car at higher speeds. Less caster gives you a car more willing to turn in at low speeds, but unstable at higher speeds. For turn in, look at 1/16 to 1/8 toe out on the front.

HWO, get camber to 2.5, if you can get caster to 6, good, but if not, don't sweat it. Camber's much more important for tire wear and grip.

PaulC
I think it has been shown that increasing castor does change the balance of the car under cornering. I agree that under static conditions with the car sitting on the scales changing the castor does not affect weight distribution. In addition if the car were set up with zero castor the tires would turn around a vetical axis, and under this condition turning the sterring wheel would also not affect weight distribution.

But when you add castor and then turn the steering wheel the front tires do not rotate around a verticle axis. This changes the weight each of the front tire carries. And therefore I believe you do have a change in balance.

I understand that you add castor to get stability. I'm saying that you can take it too far. There are trade offs in adding castor.

I think that if you were to set your car up on scales and note the weights then turn the front wheels left you would see the right front tire get lighter and the right rear tire get heavier.


Rob

Last edited by Rob500; 08-13-02 at 02:00 PM.
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Old 08-13-02, 09:23 PM
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Rob's right on the money about caster and weight jacking. When I started kart racing a few years ago, I was amazed by how much muscle the steering takes. Karts use a ton of caster with a large scrub radius to pick the inside rear tire off the ground when you turn in, and that lifting comes from your arms...
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Old 08-14-02, 01:12 PM
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oh, ok, I see what you mean.. I'm not sure I buy that it has a dramatic effect on the balance of the car, but I can see where you get the idea that caster has impact on crossweights under cornering.
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Old 08-14-02, 09:52 PM
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Originally posted by abeomid
well with netural caster, you have the easier steering, but you lose the high speed stability of the car. Toe/Caster both depend on what you want to to do. If you have an autox car, you want around -2.5Camber, +6 caster, adn 1/16" toe out in front. if it's a road race car, camber and caster are the same, but then you don't want that toe out since the high speed stability is better with no toe or toe-in

Im really glad I read that. I knew caster affected the "weight" on the steering wheel, but didnt know if affected stability. That would explain why my FC with p/s rack converted to manual feels really nice, and not too heavy, but my car is quite twitchy, especially at 80+ mph.
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Old 08-15-02, 01:25 AM
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Originally posted by mazdaspeed7



Im really glad I read that. I knew caster affected the "weight" on the steering wheel, but didnt know if affected stability. That would explain why my FC with p/s rack converted to manual feels really nice, and not too heavy, but my car is quite twitchy, especially at 80+ mph.
same here, even at dawdle speed the steering is sweet, when i'm stationary its fairly heavy, my steering wheel is only 11 inch diamter though hehehe
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Old 08-15-02, 11:54 AM
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Originally posted by Silkworm
I'm not sure I buy that it has a dramatic effect on the balance of the car, but I can see where you get the idea that caster has impact on crossweights under cornering.
It's not just an idea, it's been proven.

http://www.ground-control.com/gctalk5.htm
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