Ford 2011 Flex Owner's Manual page 246

Tires, Wheels and Loading
Weight-distributing hitch
When hooking-up a trailer using a weight-distributing hitch, always use
the following procedure:
1. Park the vehicle (without the trailer) on a level surface.
2. Measure the height of the top of the front wheel opening on the
fender, this is H1.
3. Attach the trailer to the vehicle without the weight distributing bars
connected.
4. Measure the height of the top of the front wheel opening on the
fender a second time, this is H2.
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.
246
2011 Flex (471)
Owners Guide, 1st Printing
USA (fus)