Getting 5er and truck level with each other.

Reddog1 wrote:
I have searched for causes of sway and fishtail with 5th wheels. Over and over again I read "... the fifth-wheel hitch pin is centered over the axle, unable to move laterally, which makes the fifth wheel trailer virtually immune to this motion." It beats me how someone could make that statement.

Ditto and think lost to them is the fact that the fiver pivot/mounting point is either dead centered on the TV's rear axle center line, or inches either forward or rearward of the TV rear axle center line

Meaning, zero lever arm or inches long lever arm vs a tongued trailer ball is tens of inches to several feet away from the TV's rear axle center line...meaning a much longer lever arm for any trailer sway to leverage the TV's rear end

Why PullRite was such a GREAT anti-sway WD Hitch system, but it was too heavy, added too much to under-hang (ground clearance), could NOT remove a spare tire underneath there, etc....or the current claimed best/better HA or Pro, as it projects that pivot point closer to the TV's rear axle center line. Thereby reduced lever arm length

So all trailers can and do sway...those with longer lever arms affect the TV much more.

As long as the TV is pulling and the trailer has drag...the lever arm forces are not able to do much to a TV towing a Fiver...why when a tongued trailer starts to sway...the best thing to do is to touch the trailer brake controllers manual lever...to increase trailer drag while the TV continues to pull

I also read tongue/pin weight should be more than 10% of the trailer weight. We are very limited on just how much we can do to change the pin weight on a 19 foot 5th wheel. I can't find my weight notes, but as I recall the pin weight is only 320 lbs. The trailer is 5060 lbs which should have a minimum of 500 lbs (10% percent). I think I did remove about 150 lbs from the box in the rear of the trailer, which should be the same as adding 150 to the pin. If true, I should now have about 650 lbs. I think this is borderline.

Agree, but...again that shorter lever arm of a Fiver will have less to little affect on the TV's rear axle

Tires can have an impact on sway and fishtail. As I previously stated, the OEM tires were P215/75R15. I installed GOODYEAR MARATHON ST225/75R15D. I really don't think tires are my problem.

Agree and add that, that is more important (or of higher impact) on the TV than when on the trailer

BenK suggested adding a Panhard Bar. I have experience with Panhard Bars for automotive applications, but not trailers. I have found no information for this application but I am open for discussion.

Because trailer OEMs, generally, are into "cheapest" for stuff not visible to the general buyer. How many look down there and if they did...would know what the heck about the stuff down there...

But...there is little difference in lateral (side to side loading) on a leaf spring setup between a TV with leaf spring rear suspension and a trailer with leaf spring suspension. Loading and dynamics same/similar and if lifted...exacerbated by longer lever arms and mainly focused at the shackles & leaf eye bolt(s)

A panhard rod (AKA bar) locates the axle in reference to the trailer in this case.

By doing so, it takes away most of lateral forces that would have gone to the leaf spring suspension components. Mainly the shackle and leaf eye bolt. Reference my broom handle & bar weight example

BenK also suggested shocks. For years I have observed trailers of different types, including RVs, may or may not have shocks. I do find them more often on high end trailers. I have read high psi in tires stiffen the sidewalls, but also tend to make the tires bounce. The shocks dampen the bounce. There is very little if any effect on sway of truck Campers in my experience, could be different with 5th wheels, I am open for discussion.

Again...IMHO, trailer OEMs go cheap and your comment that the high end trailers do have shocks...almost self explanatory. Or consider removing the shocks on your TV and then see how it handles...

Consider this...a tire bouncing means that while it is 'off pavement'...there is no control. No contact means no braking, cornering, etc...it is flying...

At this point, I think my 5th wheel was designed for a 1/2 ton truck in 1988, with a minimum amount of pin weight. I see my only option is to do some fabrication work, such as a spare tire mount above the pin, and maybe move the propane bottles to the front. I think that would add about 150 lbs to the pin and remove about 100 lbs from the rear. That would give me about 800 lbs total pin weight plus the removal of about 250 from the rear.

I am open for suggestions or comments. Links to shock and/or Panhard install or discussion would be appreciated.

Wayne