Use of "just as" to subordinate a clause and commas

I'm unclear when subordinate clauses that follow independent clauses should have commas. Here's my example sentence, "Charlie reaches the border of the parking lot and leaps for a plateau of grass just as the car comes to a squealing stop."
This subordinate clause beginning with "just as" is following an independent, so I shouldn't have a comma right, and additionally a comma would create a weaker bond or a break in action so that's another reason to use no comma. Plus there's nothing ambiguous about the subordinate clause the use or absence of a comma would clarify. Am I right in choosing not to have a comma?