Good news is I have photos of the wishbones that seem fairly centered and flat, so I can use the coordinates to calculate the lengths of their open ends, then put those photos into AutoCAD to approximate arm lengths, so thats something.Ĭan anyone suggest suspension analysis software I should check out? The problem is when I copied that diagram over to the side view diagram, I have to move the chassis mounts WAAAAY down on the tire to get the instant center to intersect the anti dive line. I then drew lines through the mount points to get the instant center. I went on a separate sheet and used the coordinates I had for the chassis mounts for the wishbones to plot each of those points on a side view plane (front to rear and height). I drew up a side view diagram with the correct tire size, wheelbase, and anti-dive line marked. I used some of the formulas I found along with the wheelbase, cg height, and brake bias stated in the documents I have to calculate the anti-dive figures myself, and confirmed that those two numbers for anti-dive are correct. The data I have states that this car has 87% anti-dive and an 11.8 degree anti-dive angle. I tried punching some stuff into AutoCAD last night and came up with some weird figures. for a given outer lower joint location, moving upper outer joint upwards/downwards, you alter camber gain spread, keeping lower outer ball joint height location and changing height of the upper outer ball joint, you alter one side of the camber curve, moving a wheel carrier upwards (both upper and lower outer joints by the same distance) moves camber gain curve down, There are some general relations, which might be helpful when you tweak outer coordinates: What's the PITA, is at some point you might end up getting closer and closer to match the roll center curve but in the same time, you will be getting further away from the camber gain curve. My approach is, to use pictures of a car to sort of estimate locations of outer joints (like, +/-2cm) and from there, try to move around outer points to see, in which direction you need to go with them sideways and upwards, to get closer to the curves. Having a proper suspension analysis program will help a lot. I feel like there's a formula here that will help me and I'm just not seeing kind of 'been there' already. It also doesn't help that when I try to find calculations for finding side-view instant center, they all require me to already know my mount points, which is what I'm trying to find in the first place. I guess side-view instant center is what I'm sort of trying to find in the first place, so this formula doesn't help either. This doesn't really help as I already have all of these valuesĪnti-dive % = (Side view instant center height)/(height of 100% anti-dive line at instant center distance behind the front axle) I've seen two formulas:Īnti-dive % = Brake Bias Is there any way I can use all of this information along with the coordinates I have to map out the suspension geometry in relation to the car?Ĭan you explain how I can use the Anti %'s to find the inner pickup points? I have a pretty good idea of how to map out everything in AutoCAD, I'm just not sure how to factor in anti-dive and anti-squat.ĮDIT: I've been reading a lot about anti-dive and I'm still a bit lost on how to use it to locate my chassis mount points. If they are, I also have dimensions for various springs for this car. I'm not sure if these are meant to be motion ratios (they are numbers less than one, I can't say what number exactly for confidentiality reasons). I also have one value each for front and rear called "Ratio (Wheel/Spring)". Roll Center change per suspension movement So I know where the chassis side points of the suspension are in relation to each other, but not where they are exactly on the car. I also do not have coordinates for the upper and lower wishbone mounts and steering arm mount on the wheel upright, nor do I have dimensions or angles for the wishbones. how far forward of the midpoint of the wheelbase, how far left or right of chassis centerline this point is, and how high this point is. The problem is I do not have any measurements that show me where this reference point is on the chassis i.e. I have a page that shows the Cartesian coordinates of the chassis-side mounting points for the damper, upper and lower wishbones, and steering arm, all in relation to a reference point on the chassis. I have quite a few bits of real world data for this car (I won't say which just yet), but I'm missing some very key data points that would help me plot a suspension (I'm using the ISI physics sheet). I'm trying to map out the suspension geometry for a car. I've got a very strange situation that I need some help with.
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