Pirate 4x4 banner

1 - 20 of 20 Posts

·
Registered
Joined
·
4,580 Posts
Discussion Starter #1
All other things being equal, will a longer tongue reduce or eliminate fishtailing?

Have a 16' utility trailer that has been HEAVILY modified for a specific purpose. A bit too much weight in the rear when loaded causes some sway. A new trailer is not an option. Changing the weight distribution is a PITA at best, not possible at worst. The only easy option I see is lengthening the tongue which is about as short as any trailer tongue I've ever seen.
 

·
Registered
Joined
·
614 Posts
Have you measured your current tongue weight? When the trailer is loaded and unhooked, does the tongue naturally rise?
 

·
Registered
Joined
·
220 Posts
Tongue length won't do anything if it's tail heavy. Can you move the axle(s)? Is it single or tandem? Anti sway set-up out of the question? A pic or description of the type of trailer and weight we are talking may help.
 

·
Premium Member
Joined
·
3,033 Posts
Definately need pics. How easy is it to pick up the tongue fully loaded? I've seen 20' car haulers that when loaded I could pick the tongue up with one hand.... and they were wondering why it swayed.
 

·
Registered
Joined
·
4,580 Posts
Discussion Starter #6
Have you measured your current tongue weight? When the trailer is loaded and unhooked, does the tongue naturally rise?
No and no

Tongue length won't do anything if it's tail heavy. Can you move the axle(s)? Is it single or tandem? Anti sway set-up out of the question? A pic or description of the type of trailer and weight we are talking may help.
Moving the axles is not an option. Tandem axle 16'x82". Anti-sway is mostly out of the question, the people who use this are not mechanically inclined and would not use it or understand it, plus they'd manage to destroy it or lose pieces.

However all is not lost, I believe I can lengthen the tongue and move some 5 gallon jugs of water from the rear to store at the front on the tongue, or I might get away with not modifying the tongue if I can squeeze enough water on it as-is without additional chance of jack-knifing.
 

·
Registered
Joined
·
2,147 Posts
If you are tail heavy lengthening the tongue will make it worse not better. You need to move the weight forward. You can do this by moving the axles back, moving the load forward or shortening the tongue. However you may not be able to shorten the tongue enough depending on where your load center is.

Go weigh the bitch and see where the weight is.
 

·
Premium Member
Joined
·
1,742 Posts
You need to look at this situation as a class 2 lever.



In this case the fulcrum is the axles and the effort is the tongue weight.

If the load stays the same distance from the fulcrum, and the effort moves further away from the load (lengthening the tongue) the amount of effort (tongue weight) will decrease.

A quick google search showed that anywhere from 5 to 15 percent of the total trailer weight is considered good tongue weight. How much does the trailer in question weigh? Since the only info you gave is that it is a dual axle utility trailer, I will assume 3500lb axles. If you have it loaded to the max, you would need about 700lbs of tongue weight (10%). You mentioned moving some 5 gallon buckets of water to the front. 5 gallons of water is about 40lbs. I think you will need lots of buckets to make a difference because we don't know the current tongue weight or the total weight of the trailer.

Bottom line is that you need to move the axles back or the load forward to fix your problem. However, it seems like this is one of those "here is the answer I have decided on, so I want everyone to tell me its the correct answer" type of situations.
 

·
Registered
Joined
·
12,231 Posts
Lets see the trailer. Lets see whats being loaded on it. Lets see it hooked to the vehicle that tows it.
 

·
Registered
Joined
·
8,312 Posts
Bottom line is you need to move the load forward or the axles back. I had a REALLY (and by really, I MEAN REALLLLLY) close call the other day hauling a truck on my trailer. I ran out of room to move the truck I was hauling forward and it was borderline too long for my trailer. If I had another 6" to 1' to move it ahead I woulda been golden. As it was, I had a nasty 2 lane wide fishtail I had to drive out of. Seriously scary shit right there. You DO NOT want that problem to happen if you have know nothings hauling it, they will crash in a very spectacular way.
Travis..
 

·
Registered
Joined
·
4,580 Posts
Discussion Starter #11
Bottom line is that you need to move the axles back or the load forward to fix your problem. However, it seems like this is one of those "here is the answer I have decided on, so I want everyone to tell me its the correct answer" type of situations.
Not at all. Specific numbers are irrelevant, I was asking about the principle of it, which you answered. THANK YOU.

I mistakenly ass-ume that things such as 10% tongue weight and water at ~8.3 lbs/gal are understood by all. Thank you for stating the obvious however.

I don't see why it would be hard for water to make a difference, if I could move four 5-gal jugs to the tongue that's over 160lbs on the tongue and the same amount off the rear of the trailer. In the face of an ideal 700# tongue weight 160 is nothing to scoff at.

Thank you all, you've answered my question!! My brain-CAD couldn't decide if lengthening the tongue effectively made for a longer trailer (after all, you ARE moving the axles back) but I see now I also have to move the load in relation to the axles!
 

·
Registered
Joined
·
220 Posts
It's axles back in relation to the deck, not overall trailer length. Every foot of deck, your axle(s) centerpoint should be an inch aft of deck center, as a general rule of thumb.
 

·
Premium Member
Joined
·
5,013 Posts
Since it seems you can't move the primary load forward (whatever it is), then moving anything else you can is the obvious choice. In this case your water jugs. Heck you could even just plain add some weight to the front (bar-bell weights, misc steel, spare tire etc), anything you can move from the rear or even middle to the front to help counter the rear weight would be a step in the right direction. If you have to make the tongue a little longer to get more weight up front that may not be a bad thing, especially if its stupid short as it is.

Whats the load? Send up a picture. Maybe making the tongue longer will somehow allow you to move the load forward a couple inches without too much effort???
 

·
Registered
Joined
·
889 Posts
Yes, with no other changes, a longer tongue will make it more-difficult for the trailer's weight to push the tug sideways (sway).

Tongue weight actually INCREASES the tendency of a trailer to sway, but it also INCREASES the tug's ability to control & survive the sway because its rear axle stays planted. Trailer sway comes from 3 things:
1) trailer mass being AWAY from its tires (like water jugs at EITHER end), which gives the trailer high angular momentum;
2) trailer flex, particularly in the sidewalls & tongue, allowing that angular momentum to find a resonant frequency when swaying;
3) tug flex, particularly in the sidewalls AND by having relatively low mass compared to the trailer OR by the tug having a long rear axle overhang to the hitch, allowing the trailer's resonant sway to be transferred easily to the tug chassis making IT sway.

Moving the tug away from the trailer's center (either by moving trailer mass over the axles, OR by moving the trailer away from the hitch, but NOT by moving the hitch away from the tug's rear axle) will reduce the amount of force the trailer's swaying torque can apply to the tug in the same way that a winch's constant torque applies less force to its cable as the drum layers stack up. It's also why a gooseneck or 5th wheel is so much more stable - both pivot on the tug where it's far less-susceptible to trailer-induced sway: between the axles.

So lengthening the tongue is probably the most-expensive way to reduce sway. It would be much safer to put new trailer-specific tires on the trailer, air them up, and put TPMS in them with a portable head that can be quickly transferred between the trucks that tow this trailer. Putting good tires on the truck, and keeping them aired up, would help, too.
 

·
Registered
Joined
·
1,191 Posts
Sorta OT but why do some of those dump truck pup trailers have a 30-foot tongue? I know it doesn't bear "tongue weight" but the ones I see out west are EXTREMELY long
 

·
Registered
Joined
·
220 Posts
Less likely to flip over in a turn. Or won't allow a sharp turn as easy for the non-thinking driver.
 

·
Premium Member
Joined
·
2,212 Posts
So they can get the trailer out of the way to dump the truck bed.
 

·
Registered
Joined
·
60,133 Posts
A good tongue weight is a minimum of 12-15%. BARE MINIMUM of 10%.

Anything less than that and you are at risk of having sway issues.

If you can't shift weight around or move the axles, another option is always adding ballast to the front.

While tongue weight taken to an extreme will cause sway, the most common cause of sway is lack of tongue weight. Another cause of sway is the driver.
 

·
Premium Member
Joined
·
3,722 Posts
leverage is leverage. i did a whole write up for you with calculated weights vs length determining force and pendulum to explain this and the stupid computer refreshed.... so F-it. basically to counter act 1000 lbs excess on the ass you can add a 30’ tongue but you still have to have the weight on the front of the long ass new tongue to Leverage that excess on the other end. its all math. the longer front end will give you more force and require less of a counter balance but it still requires a counter weight x number of feet forward to create the force to offset the weight existing on the other end of the arm.

10-15% pin weight to trailer weight and if you make it ass heave it’ll spend all day lifting your trucks ass on every overpass.



dump truck trailers are a whole different animal the weight of the trailer is supported over 2 or 3 axles with a pivoting jeep axle. or a dolly. so my understanding right or wrong is that its geometry is focused around pulling force not pin weight and leverage because it is self supported.
 

·
Registered
Joined
·
5,455 Posts
Bridge laws and also so they can dump the truck without unhooking the trailer.

Sorta OT but why do some of those dump truck pup trailers have a 30-foot tongue? I know it doesn't bear "tongue weight" but the ones I see out west are EXTREMELY long
 
1 - 20 of 20 Posts
Top