FORD 2012 Flex v.1 - Manual (Page 243)

5. Install and adjust the tension in the weight distributing bars so that
the height of the front fender is approximately halfway between H1 and
H2.
6. Check that the trailer is level. If not level, adjust the ball height
accordingly and repeat Steps 3–6.
WARNING: Do not adjust a weight-distributing hitch to any
position where the rear bumper of the vehicle is higher than it
was before attaching the trailer. Doing so will defeat the function of
the weight-distributing hitch, which may cause unpredictable handling,
and could result in serious personal injury.
Safety chains
Always connect the trailer’s safety chains to the frame or hook retainers
of the vehicle hitch. To connect the trailer’s safety chains, cross the
chains under the trailer tongue and allow slack for turning corners.
If you use a rental trailer, follow the instructions that the rental agency
gives to you.
Do not attach safety chains to the bumper.
Trailer brakes
Electric brakes and manual, automatic or surge-type trailer brakes are
safe if installed properly and adjusted to the manufacturer’s
specifications. The trailer brakes must meet local and Federal
regulations.
WARNING: Do not connect a trailer’s hydraulic brake system
directly to your vehicle’s brake system. Your vehicle may not
have enough braking power and your chances of having a collision
greatly increase.
The braking system of the tow vehicle is rated for operation at the
GVWR not GCWR.
Tires, Wheels and Loading
243
2012 Flex (471)
Owners Guide, 1st Printing
USA (fus)