How could I keep the CFrame rotation matrix, when I change a parts position?

I have a gate script that moves it up and down, but it seems to set the orientation back to 0,0,0 instead of 0,90,0. Any help? Here is the Server Script:

local TweenService = game:GetService("TweenService")
local door1 = script.Parent.Parent.Parent.Part1
local tweeningInformation = TweenInfo.new(
    2,   
    Enum.EasingStyle.Linear,
    Enum.EasingDirection.Out,
    0,
    false,
    0
)
local door1Open = {CFrame = CFrame.new(-161.498, 15.143, -125.72)}
local door1Close = {CFrame = CFrame.new(-161.498, 5.666, -125.72)}
local tween1open = TweenService:Create(door1,tweeningInformation,door1Open)
local tween1close = TweenService:Create(door1,tweeningInformation,door1Close)
 local open = false
script.Parent.ClickDetector.MouseClick:Connect(function()
	if not open then 
	open = true
    tween1open:Play()
	else
    tween1close:Play()
open = false
	end
end)

This should work since your rotation matrix starts out with zeros:

I tested it out with two parts applying the rotation of the oldPart to the newPart, but idea's still the same.

newPart = game.Workspace.newPart --part you want to apply the rotation to
oldPart = game.Workspace.oldRotatedPart --Part you want to keep the rotation of 

rotation = (oldPart.CFrame - oldPart.CFrame.p) -- subtract position to get the rotation
newPart.CFrame = newPart.CFrame * rotation --apply rotation to part you want to be rotated