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Old 08-10-2012, 12:44 AM   #3346
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Then you must not be running any droop because until you remove all the droop by adjusting the spring collar then you are not adding any load to the spring...so it isn't being pre-loaded.
egad! what are you my mother? leave me alone!! You are really getting to be annoying!
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Old 08-10-2012, 04:05 AM   #3347
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egad! what are you my mother? leave me alone!! You are really getting to be annoying!
Please move on.
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Old 08-10-2012, 07:55 AM   #3348
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Typical 1/12 suspension diagram....

You'll notice that changing the upper link's angle/length will change the instant center, which will also change the RC, though in a more subtle fashion than moving lower arm. The lower link is non moving, but still is used the same as a dynamic lower arm for these purposes (it is just a horizontal line located on the lower pivot balls). Changing the height of the lower arm will also change the roll center, so changing the ride height, while crude, changes the RC. If there is a way to move the stationary lower link in relation to the chassis that will work also.
Only thing is that this is a "static" diagram! Droop is the only way you can control the actual chassis roll , that is not a bad thing but nowhere near the same effect as the rear suspension. Droop becomes the lower arms and its virtually impossible to figure out how much the chassis is actually rolling because the springs are a huge part in this.
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Old 08-10-2012, 08:18 AM   #3349
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Only thing is that this is a "static" diagram! Droop is the only way you can control the actual chassis roll , that is not a bad thing but nowhere near the same effect as the rear suspension. Droop becomes the lower arms and its virtually impossible to figure out how much the chassis is actually rolling because the springs are a huge part in this.
I will prepare to be bombarded after I make this statement, but to be able to find a true instant center, you really need to have a lower arm that pivots, because you project the point in space of that lower pivot out to where it intersects the angle of the upper arm. In most instances you want the instant center outside the tire. The longer the instant center, the more stable, but less responsive the car will be. A kingpin front end moves vertically as opposed to swinging in an arc, so the million dollar question would be, does it have a true " roll center"
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Old 08-10-2012, 08:45 AM   #3350
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I will prepare to be bombarded after I make this statement, but to be able to find a true instant center, you really need to have a lower arm that pivots, because you project the point in space of that lower pivot out to where it intersects the angle of the upper arm. In most instances you want the instant center outside the tire. The longer the instant center, the more stable, but less responsive the car will be. A kingpin front end moves vertically as opposed to swinging in an arc, so the million dollar question would be, does it have a true " roll center"

I agree.
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Old 08-10-2012, 09:17 AM   #3351
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I agree.
WOW, I expected at least a little pushback. Im not a gambler, but lets try another one. So with a pancar style design, that doesnt necessarily "roll" around a center, it is more critical to optimize the front to rear balance. On the FGX the primary method for this is rear droop. In saying that you need to look at the function of each component.
The shock or damper is for just that, damping, or controlling the motion. the springs primary function is to hold the chassis up off the ground, while its secondary function is to provide resistance against the dampening. IMO the first order of business on any chassis should be to get the weight transfer right. Shock length/droop adjustment should be the primary adjustment here.Damping should be adjusted based on the surface consistency of the track, and spring rates to adjust for the grip level of the track
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Old 08-10-2012, 11:08 AM   #3352
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WOW, I expected at least a little pushback. Im not a gambler, but lets try another one. So with a pancar style design, that doesnt necessarily "roll" around a center, it is more critical to optimize the front to rear balance. On the FGX the primary method for this is rear droop. In saying that you need to look at the function of each component.
The shock or damper is for just that, damping, or controlling the motion. the springs primary function is to hold the chassis up off the ground, while its secondary function is to provide resistance against the dampening. IMO the first order of business on any chassis should be to get the weight transfer right. Shock length/droop adjustment should be the primary adjustment here.Damping should be adjusted based on the surface consistency of the track, and spring rates to adjust for the grip level of the track
This is leading to some good information! Im not exactly following what you are saying but i think we are on the same page Lately I have "clicked " with the pancar thing over the past two months i have managed to separate myself form the pack. At this point with my car i usually end up only changing the front springs to suit the track conditions. what i realized is that the rear damping/spring must coordinate with the front springs and droop. On the FGX with kingpin front using alot of droop (1.5/2mm) will pair the front with the rear alot better. With so much rear travel available and so little front the chassis has no choice but to lift the inside tire.

This is one of the main reasons my Upper deck kit works so well because it has more lateral flex than the stock unit and that keeps the front tires on the ground.
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Old 08-10-2012, 11:45 AM   #3353
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I agree.


Noooooooooo Bombard him bombard him.

I have no clue, this stuff is so far above my level of comprehension. I have hard enough time picking out colors.
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Old 08-10-2012, 12:33 PM   #3354
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What little grey matter I have left is hurting. Isn't this a hobby.
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Old 08-10-2012, 01:41 PM   #3355
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Old 08-10-2012, 01:59 PM   #3356
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What little grey matter I have left is hurting. Isn't this a hobby.
Yes it is a hobby, but the days of building a kit and racing it are long gone. If you are going to race and be competitive, its the approach that you need to take. Trust me it took me a long time to understand all of this, but once I got a grasp on it, it made things a lot more fun, because i wasn't sitting around scratching my head when the car wasn't working
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Old 08-10-2012, 01:59 PM   #3357
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Only thing is that this is a "static" diagram! Droop is the only way you can control the actual chassis roll , that is not a bad thing but nowhere near the same effect as the rear suspension. Droop becomes the lower arms and its virtually impossible to figure out how much the chassis is actually rolling because the springs are a huge part in this.
The upper arm on that diagram can be adjusted in height which will change the angle of the upper arm. Also most pan car suspensions have a way to move the upper arm mounts more inward which will change both the angle and the length of the upper arm.
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Old 08-10-2012, 03:56 PM   #3358
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I will prepare to be bombarded after I make this statement, but to be able to find a true instant center, you really need to have a lower arm that pivots, because you project the point in space of that lower pivot out to where it intersects the angle of the upper arm. In most instances you want the instant center outside the tire. The longer the instant center, the more stable, but less responsive the car will be. A kingpin front end moves vertically as opposed to swinging in an arc, so the million dollar question would be, does it have a true " roll center"
If you look closely at the diagram, the IC is actually where the upper arm's line intersects the horizontal line of the lower "arm". The IC is slightly outside the end of the lower arm. If you raised the upper arm, the IC would now move away from chassis centerline.
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Old 08-10-2012, 03:57 PM   #3359
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Last edited by robk; 08-10-2012 at 04:09 PM. Reason: Better illustration...
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Old 08-10-2012, 06:07 PM   #3360
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the knuckle is in the same position on those diagrams, what happens when the knuckles moves up while the opposite side knuckle is limited because it cannot go down like a normal suspension would? Twisting the chassis is not what happens on the track. Not saying you are wrong but those sketches dont really tell us anything unless you have a way to simulate the upper arms moving. You only really get about 2mm or so of travel at most.
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