Is there any way of rotating a part while it is unanchored?

Ok so I have a problem at the minute where I am trying to make a police lightbar with rotating lights. The car has to be unanchored to move about however the lightbar can't function unanchored.

Is there anyway of allowing the part to rotate while being unanchored? I have the script here.

sphere = script.Parent --This means that you have to have the script in the sphere part

  

a = 0

off = 0

  

repeat

sphere.Rotation = Vector3.new( 0, a, 0) --The second value of vector3 is a,

wait(.01) -- we wait .01 seconds,

a = a+13 --a's value increases

until off == 1

create a weld for them to stick together without being anchored, u do this by doing the following

local weld = Instance.new("Weld")--creates a weld
weld.Parent = lightbar here--parents it to the lightbar
weld.Part1 = lightpart here--this sticks to part1
weld.Part0 = car part to stick to here--stick it to part0