I hadn't seen that alan bolt lock before. Does it have anything to keep it from rattling back and forth in the hole when inserted and locked?
Its a new device they offer...and yes you can tighten it down so there is no rattle...
There is a document on the 1upusa web site that shows all of the dimensions in all of the tilted configurations with lots of measurements.
quikrackdouble.pdf
It looks like it hangs 39.85 inches out from the end of the hitch and 15.95 inches below the bottom of the hitch when tilted down with 2 add-ons (4 bike configuration).
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Yes you might still be able to tilt it down with 4 bike...I just don't have that configuration
That's odd. On my single rack I just pull a lever bar and it tilts right away - no ball screw to rotate at all...?
There is a spring loaded, finger rotatable ball screw that locks the lever bar into position so the lever bar will not accidentally become disengaged from the detents in which it sits. It is probably not needed as the lever bar is also spring loaded and likely would not move, but the ball screw locking mechanism is another level of security...