I used to use a single friction sway controller with our previous camper (3000 lbs popup) and minivan. Was using a 400lb rated Single Bar WDH.
The thing about friction sway controllers is that many do not know how to set them properly, and simply trust the dealer to set up. You will get people telling you:
-just snug up the lever
-push on lever until you get a white mark on your hand...that's enough
-push lever until parallel with trailer frame
All of these suggestions may or may not be enough, depending on your definition of "snug", or how thick your skin is, etc. Problem is that the lever is actually an on/off switch, not the means for adjusting.
The correct way to set up a friction sway controller is to tighten it "all the way", that is "bottom out the threads". The lever will stop turning when the nut it is attached to bottoms out on the body of the controller. Any further force will bend the lever, since it can't turn any more.
So how do you adjust it? With the adjuster nut, which is on the other side of the plate from the on/off handle. But first, make sure you have at least 10% of loaded trailer weight on the ball as tongue weight. Until you do this, the sway controllers will only be band-aids for a poorly set-up rig, and may never be able to handle the sway.
Once loaded properly, engage WDH properly (front wheel well height is the same as when trailer not attached, and trailer is level), and fully tighten the sway controllers' handle. Fully! Since you have 2 controllers, I would recommend loosening the adjuster nuts on both, and tightening to about the same amount/torque. This simply to ensure that they are working equally. If these are old, you may also want to pull the arm out of the body to see fo the pads are worn away, and or glazed. If things look bad replace them. Also, when tightened (handle "on") you should not be able to pull the 2 parts by hand. If you can, the pad are probably shot. Replace.
Get out on the expressway, making sure you take a proper size wrench for that adjuster nut(s). Flick the steering wheel 1 way, then back to center.
If the trailer swings more than once in each direction, I call that "sway". Pull over, and tighten both adjuster nuts 1/4 turn. Get back on the road and try again. Repeat in these small increments until the trailer will only swing at most 1 time in each direction.
If on the first try, the trailer does not "sway", you may have them tightened too much. in that case, back off in 1/4 turn increments until you do get sway, then tighten 1/4 turn.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller