RC car axle suspension acts weird?

So I'm trying to create animated axle suspension for an RC car that I'm trying to make.

I've attached a link to the RC car. The axle suspension code is in the FL wheel only.

When you start, it looks fine, but when you start driving it, it goes up and down and all around! I'm pretty sure cause it acts on the X and Z axis only, but I'm not sure on how to make it work only on the Y axis, cause that's the axis where the wheels go up and down.

Code by @ToldFable on devforum, modified by me:

-- define some variables
CharPart = script.Parent.Parent.Phys
Hinge = script.Parent.Chassis
RootPart = Hinge.Parent

while wait() do
    -- define position of origin
    HKpos = Vector2.new(RootPart.Position.X,RootPart.Position.Z)
    -- define position of target
    XYpos = Vector2.new(CharPart.Position.X,CharPart.Position.Z)

    -- the ratio to get the triangle's width over the height
    ratio = (XYpos.Y-HKpos.Y)/(XYpos.X-HKpos.X)
    beta = math.atan(ratio) -- converting this to radians

    -- turn it from radians into degrees
    beta = beta*(180/math.pi)

    print(beta)
    Hinge.TargetAngle = -beta -- beta has to be negative so it points at you

end

Model to explain in further detail: https://www.roblox.com/library/7418794485/table-wedges