Why wont this break welds?

-- SETTINGS --

IsAnchored = false  -- Set this to true if you want to make it unable to move before breaking welds

Speed = 25 -- The ammount of speed (in SPS) you need to reach to break welds 

Remove = false -- Set this to true if you want to auto-delete destroyed blockade after a specified time.

RemoveTime = 10  -- How long (in seconds) before auto-deleting destroyed welds (if Remove is true)

-- SCRIPT --

local P			= script.Parent
local mainPart	= P.Main
local weldedParts = {}
table.insert(weldedParts,mainPart)

function Weld(x, y)
	local weld = Instance.new("Weld") 
	weld.Part0 = x
	weld.Part1 = y
	local CJ = CFrame.new(x.Position) 
	weld.C0 = x.CFrame:inverse() * CJ  
	weld.C1 = y.CFrame:inverse() * CJ  
	weld.Parent = x	
	table.insert(weldedParts,y)
end

function WeldRec(instance)
	local childs = instance:GetChildren()
	for _,v in pairs(childs) do
		if v:IsA("BasePart") then
			Weld(mainPart, v)
			script.Parent.Main.Anchored = IsAnchored
		end
		WeldRec(v)
	end	
end

WeldRec(P)

function onTouched(part)
	local h = part
	if h.Velocity.Magnitude >= Speed then
		script.Parent.Main:Destroy()
		wait(RemoveTime)
		if Remove == true then 
				for _,v in pairs(weldedParts) do
	if v:IsA("BasePart") then
		v:Destroy()
	end
end
		end
	
	end
end

script.Parent.Main.Touched:connect(onTouched)

This should, when a car hits it at over 25SPS, break all welds in a model.