fordownr wrote:
RPMTZIG,
Please check with your FORD dealer as there are MANY possible issues (Technical Service Bulletins) with the combination you are describing. I have a 2011 F-150 Super crew (5.0 Ltr) towing a Keystone passport (~7500 lbs fully loaded). Have a significant shimmy/stutter when first taking off but it goes away above 25MPH. Ford has replaced the driveshaft, Trans Mounts, and put new springs under the rear end, but still have the issue.
Separate loaded weights are:
Truck front 3480, rear 3080
Trailer 7520
Connected weights are:
Truck front 3400, Rear 4280
Trailer 6360
We are using a Blue Ox weight distributing hitch (BWX1000) and the truck and trailer combined are on plane.
They may be 'on plane,' but I honestly can't imagine that hitch is adjusted properly. A properly adjusted wd hitch should put some weight on the drive axle, some on the steer axle, and some back on the axles of the trailer. You have 1,200 pounds (which is likely the entire tongue weight of the trailer) registering entirely on your rear axle.
I don't know that this would cause any of the shaking you are indicating (can't imagine why it would), but it could certainly exacerbate any underlying issues you may have. FWIW - I'd go back and check your set-up and see if you can't tweak it.