Too much tongue weight - trailer frame/coupler issues? - Fiberglass RV


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Old 10-23-2017, 07:25 PM   #1
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Too much tongue weight - trailer frame/coupler issues?

Hi All,

Quick question to throw out there - would love opinions and especially real life experiences.

Tongue weight! I have read all the stuff. 10-15%, more weight effects front tire traction of TV, etc. Less = sway. I agree with all this completely! Question is not on that topic.

But what I want to know is how much tongue weight is too much tongue weight "for the trailer coupler/frame/welds, etc" itself? Lets assume the truck is a 5 ton lol and can handle a tank, no squat, etc.

How much tongue weight can be safely added to the tongue before trailer/coupler issues?

I ask because I know I am front heavy. I put (2) 6v batteries, and (2) propane tanks up there. I also load front closet with food, and load bathroom floor with Gatorade etc. I have not weighed tongue weight - I know I should. My half ton handles it great. But am I pushing the limit of the frame/coupler design? I do have a rather thick 4" channel frame.

Thank you very much!!!
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Old 10-23-2017, 07:34 PM   #2
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Each part of your towing system has limits: the tow vehicle has load capacity as well as towing capacity. The receiver has a load capacity and the hitch (part that slides into the receiver) has a load capacity as well as the ball is load rated.

All of the parts of the tow system have to be rated to carry the load to which each part is subjected. You have to read to know the capacity of each part. I've not been able to find a hitch that is rated beyond 7,500 pounds but I suspect that you're expected to move up to an Equalizer Hitch with Sway Control when you get into very high load weights.

The point here is that each part of your "tow system" must be evaluated for the load. AND I think this question/thread belongs in the towing section of the forum and not in the general discussions.
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Old 10-23-2017, 07:43 PM   #3
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Originally Posted by JWScarab View Post
Hi All,

Quick question to throw out there - would love opinions and especially real life experiences.

Tongue weight! I have read all the stuff. 10-15%, more weight effects front tire traction of TV, etc. Less = sway. I agree with all this completely! Question is not on that topic.

But what I want to know is how much tongue weight is too much tongue weight "for the trailer coupler/frame/welds, etc" itself? Lets assume the truck is a 5 ton lol and can handle a tank, no squat, etc.

How much tongue weight can be safely added to the tongue before trailer/coupler issues?

I ask because I know I am front heavy. I put (2) 6v batteries, and (2) propane tanks up there. I also load front closet with food, and load bathroom floor with Gatorade etc. I have not weighed tongue weight - I know I should. My half ton handles it great. But am I pushing the limit of the frame/coupler design? I do have a rather thick 4" channel frame.

Thank you very much!!!
Start by reading the Manual for the Silverado. The maximum tongue weight should be listed.

More questions for you to answer. Is the hitch factory or aftermarket?
The reason I asked is that's second most likely limiting item.

Weigh the tongue of the trailer.

My guess is that don't have a thing to worry about.
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Old 10-23-2017, 07:51 PM   #4
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Truck is ok.

Hi all. My truck is ok. Tow rated 6500. Heavy duty half suspension. Full size truck V8. Factory tow package. Factory receiver. 5000lb hitch and ball. No worries there!

I'm curious sbout the trailer itself only. Is the coupler (correct term?) part that is welded to the frame overloaded? The part that slips over the ball. Will heavy tongue weight cause it to crack or welds to crack where it's welded to frame? Is frame strong enough? That's pretty much my concern, trailer tongue only.

Agree towing section would be better, oops, not sure how to move thread.

Thanks again!

Moderator note: This thread has been moved from General Chat to the Towing forum.
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Old 10-23-2017, 08:37 PM   #5
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Seems you have two unknowns in this equation. Solutions are much easier with fewer unknowns. Drag your bathroom scale out to the trailer and find out the tongue weight. If too much for the scale just set up a beam supported by a brick on one end and the scale on the other. Put the tongue in the middle of the beam and multiply the scale reading by two.

BTW. A 5000 pound hitch doesn't mean you can safely carry a 5000 pound tongue weight.

Personally I would worry if my Scamp's tongue weighed over 300 pounds, though I have no data from Scamp's engineers. OTOH- folks on this forum report broken frames on occasion. I keep mine at 200 pounds with load shifting.

You can always carry a few bikes on the back to compensate. ;-)
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Old 10-23-2017, 09:35 PM   #6
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Originally Posted by JWScarab View Post
Hi all. My truck is ok. Tow rated 6500. Heavy duty half suspension. Full size truck V8. Factory tow package. Factory receiver. 5000lb hitch and ball. No worries there!

I'm curious sbout the trailer itself only. Is the coupler (correct term?) part that is welded to the frame overloaded? The part that slips over the ball. Will heavy tongue weight cause it to crack or welds to crack where it's welded to frame? Is frame strong enough? That's pretty much my concern, trailer tongue only.

Agree toeing section would be better, oops, not sure how to move thread.

Thanks again!
Hi Joe,

It seems that the coupler has a rating stamped on it. Then there is the question of whether the weld was performed properly, whether there are undercuts or other defects, or signs of the coupler or frame having been overheated. However, if the coupler is of adequate rating, I would not expect the welding to be of concern as so many couplers get welded everyday and I've never heard of them failing in this manner.

As to the A-frame, I think it would be a pretty simple beam equation to evaluate its capacity, but maybe that's only because I don't know how to do it properly!

Steel is equally strong in tension and compression. The lower edge of your frame between the coupler and the axle is stretched in tension by all the load you are adding in the front, while the top is compressed.

You might find a sympathetic mechanical or structural engineer who could evaluate it. Or perhaps your welder could give you some assurance based on their practical experience.
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Old 10-23-2017, 10:34 PM   #7
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Originally Posted by JWScarab View Post
But what I want to know is how much tongue weight is too much tongue weight "for the trailer coupler/frame/welds, etc" itself? Lets assume the truck is a 5 ton lol and can handle a tank, no squat, etc.
Simply refer to the GVWR of the trailer itself. What does the manufacturer say the maximum is? I've found that the manufacturer's maximum GVW seems to always consider that 10% of the weight is resting on the hitch. Follow the manufacturer's specs. None of us here know better than the manufacturer what the maximum can be, and none of us are in a position to guarantee the results if we tell you to do something the manufacturer says not to.

Maybe you could get a starting point weight of what is sitting on the axle, and a weight at the hitch. Then you could keep track of the modifications and weigh it again to see how it turned out.

It's also reasonable to identify any known weak spots in the frame and beef them up as needed.

Lengthening the tongue will lower the apparent weight at the ball and make the trailer more stable while towing, while transferring some weight to the axle. Adding more stuff on the tongue will add stress where the frame meets the body. The back of the tongue/front of the body, is where I've strengthened frames before because of this stress.

The coupler should be fine as long as you are within the listed overall weight limits stamped on the coupler itself.
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Old 10-24-2017, 04:52 AM   #8
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weight

I too have looked at all this stuff especially welds but welds are all over our cars too. Its amazing to me and I am not a welder don't propose to be how all this steel is joined together with welds and everything stays together!

I guess we need to use common sense in how we put our loads together and be aware there are limits. For me I only run on battery and one propane tank on my tounge, I also don't load the front end of our little 13f with a lot.

I don't try to out engineer the engineers all this stuff has been going on for centuries not to say you don't see some odd stuff out there, dangerous stuff for me.

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Old 10-24-2017, 06:23 AM   #9
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Ok, very good replies!! Thank you everybody. I didn't realize the weight stamped on the coupler - but that's probably because, well, I didn't look....lol !! I will do that tonight. Also, the bathroom scale I always assumed would break (it almost breaks when I stand on it). But the beam idea cutting weight in half is awesome idea!! I will do that too!! I'll report back with those numbers. I think I am probably ok, but I will verify and reply.

But my knowns. I added (2) propane tanks at 37lbs each. I also added (2) batteries at 62lbs each. I removed (1) battery at 40?lbs. I also welded thick rear bumper and hitch to back at 45?lbs. And I took the spare tire out of the front closet and put it on the back 45?lbs.

So I added 90lbs to rear. I added maybe 120lbs to front. Im guessing its a 1/3 to 2/3 offset, so 90lbs at rear takes off 60lbs at front. So I am approx 60lbs heavier than it was designed. ROUGH math....lol.

It just SEEMS so heavy to me when I hook up! - idk, maybe a worry wart. Also, I noticed Casita adds an angled gusset from the rear of the coupler down to the top of frame at an angle. I'm sure this helps! Mine is just the coupler welded to top of frame period - but no gussets added. IDK why I worry about all this stuff.....ask my wife, I drive her nuts!
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Old 10-24-2017, 06:50 AM   #10
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Scamp's 2" coupler is rated for 5000 pounds. That means it should be good for 500+ pounds of hitch weight. No worries there.

It's the front of the Scamp frame starting where it transitions to the A-frame I would worry about. The transition is the common failure point on older units, and at some point they beefed up the design.

The real issue is the break in the curb side frame rail to accommodate the entry floor at the door. It creates a weakness in the front.

I would take Mike's advice and let a welder with a lot of experience building and repairing trailers look at it.
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Old 10-24-2017, 09:07 AM   #11
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While you are at it, you may want to double check the load rating on the trailer tires. I think it may be a letter, but you can probably convert it on the web if weights aren't stamped on the tire.
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Old 10-24-2017, 09:13 AM   #12
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my a-liner had load d tires on it my 13f scamper load c I don't understand scamps thinking on this?

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Old 10-24-2017, 09:15 AM   #13
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My tongue is bolted on sort of different


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Old 10-24-2017, 09:48 AM   #14
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Of course the OP's trailer is an Eggcamper, It is an an interesting question though and one which applies toa all makes and one which has not been explored here, to my recollection.

The 10% rating on TVs is both recent and clearly arbitrary. It is also contrary to every major aftermarket hitch manufacturer's ratings.
In fact 10% has been (and still is some cases) considered minimum tongue weight with 15% at the high end, up until J2807. Even then, the manufacturer's recommendations are set at 10% based only on the the fact that the J2807 test used 10% not claiming it should be a maximum.
I don't know who designed the frame structures of the various trailers on the market (engineers?) or how well design specs have been met in execution, but the coupler's rating is for the coupler not the frame.
We have seen frame failures from fatigue of over 30 years on early thin guage frames, up to design flaw failures on modern trailers resulting in recalls on some newer makes.
I submit that there is not likely any modern RV trailer on the market with a real tongue capacity of less than 15% of the trailers overall weight and in most cases it would be higher. This is conjecture based on limited experience like other opinions on this thread, and assumes a trailer properly built to design specifications.
At any rate, 15% would be a generally accepted maximum for stability.
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Old 10-24-2017, 10:06 AM   #15
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Of course the OP's trailer is an Eggcamper..
A fact I completely missed... oops!
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Old 10-24-2017, 10:09 AM   #16
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Originally Posted by JWScarab View Post
But my knowns. I added (2) propane tanks at 37lbs each. I also added (2) batteries at 62lbs each. I removed (1) battery at 40?lbs. I also welded thick rear bumper and hitch to back at 45?lbs. And I took the spare tire out of the front closet and put it on the back 45?lbs.

So I added 90lbs to rear. I added maybe 120lbs to front. Im guessing its a 1/3 to 2/3 offset, so 90lbs at rear takes off 60lbs at front. So I am approx 60lbs heavier than it was designed. ROUGH math....lol.

It just SEEMS so heavy to me when I hook up! - idk, maybe a worry wart. Also, I noticed Casita adds an angled gusset from the rear of the coupler down to the top of frame at an angle. I'm sure this helps! Mine is just the coupler welded to top of frame period - but no gussets added. IDK why I worry about all this stuff.....ask my wife, I drive her nuts!
Joe,

I don't know that the Casita's arrangement is to strengthen things so much as to change the vertical location of the coupler.

The change in load on the ball for different scenarios can be figured out pretty easily if you take some measurements.

This process will give you the change in the tongue weight. If it's too heavy, travel with empty propane cylinders; problem solved!

1) Consider loads located in front of the axle as positive and loads behind the axle negative.

2) Pick your favorite convenient units for weight and distance such as pounds and inches.

3) Multiply the load weight times the distance from the axle.

4) Add them all up and divide by the distance from the axle to the ball.

Here's an example where I considered replacing the two 20# cylinders on the Casita with 11# cylinders, moving the new cylinders forward four inches so that I could carry a canopy between the shell and the cylinders, and adding two folding bikes in a storage box at the rear bumper. The blue numbers are inputs and the reddish numbers are calculated.

Mind you this will basically calculate a static condition, like a teeter-totter at rest. It does not take into consideration the potential issues associated moving loads further from the axle which can affect the dynamic behavior by changing the polar moment of inertia. In other words, a trailer with two 1,000 lbs loads located ten feet from the axle will have less stability when towing than a trailer with a single 2,000 lb load centered over the axle.

However, it does give you a way to predict the impact of potential future changes, or to evaluate what you have already changed.
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Old 10-24-2017, 06:18 PM   #17
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5000/700

Thanks all for the tips! Great into on coupler/frame Floyd, and a great method of calculating the front/rear weight Mike!!

So today looked closer lol. 5000lbs trailer weight / 700 lbs tongue load. So my frame is 4" C channel. It is bent in a curve as it exits the body and angles to the ball, so there are no welds - just a gentle bend. Frame is not cut entire length. I can only assume its more then robust enough.

So lastly, it looks like they welded smaller C channels to the top of the frame at the very front to match the coupler length, angle, and inner wall. Then slipped the coupler over the C channels and welded it to the c channels and to the 4" frame both. I hope that makes sense. It seems to look like a robust setup. I can only guess its more than sufficient.

So I feel better digging into this to understand. I appreciate everybodys replies!

Tires are 2540 lbs D load each, up to 65psi. Wheels 80psi, and valves stems 100psi. Axle 3500.

I still intend to weigh entire trailer, and tongue just for info!! Will report back in a few days!

Thanks again!
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Old 10-25-2017, 09:23 AM   #18
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First let's start at the TV. My 2007 Silverado Z71 recommended a WDH for 600 pounds or more tongue weight.

Tongue weight scales are handy for weighting not only the tongue weight but also measuring a trailer at three points then adding them together giving you the total weight. I have a Sherline scale and have measured tongue weights at few rallies.
The average 17' Deluxe Casita with full propane tanks is going have a tongue weight of just a tad over 400# and that's about 15% of the trailer's weight.
My 1999 17' SD ready to travel has been just under 3000# four years in a row.
I've weighted 17' Casita trailers at rallies and only two were 500#s. One had a generator on the tongue and I don't know what was in the second one making it so heavy.

Casita lists the DRY weight of their 17' Deluxe (with bath) trailers at 2480#'s
With a tongue weight of 365#s.
Spirit 16' & 17' | Casita Travel Trailers - America's Favorite Lightweight Travel Trailers!

Some will argue but I have personally verified weighting my 1999 17' SD that they are real life DRY weights.
The axle is rated at 3500 pounds total or 1750 per wheel and looking at Good Year's chart shows my 205/75r15 "D" rated tires at 55psi have 1940 pounds capacity or 3880 for two that is 330 pounds over the capacity of the 3500# axle.
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

Back to frames.
Casita uses a 3" conman grade channel that flexes with a normal 400# tongue weight.
More than a few including a retired structural engineer who has a new 17' Casita SD thinks this is not enough.
As Casita 17' trailers age the area of the frame just under the front of the trailer flex more and or bend and a good indication of that is the door no longer being centered in the door frame causing the door to rub and stick.
Based on that I believe JWScarab's trailer with a 4" channel frame he should be fine.

Joe

I forgot to add that I have straightened the bottom of my frame from the hitch to the axle and no longer have flexing.
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Old 10-25-2017, 07:04 PM   #19
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I do have a rather thick 4" channel frame.
Joe,

Just to confirm, you do have C 4 channel, not the cold-formed stuff with a uniform thickness that looks like folded sheet metal, right?

For some reason I was under the impression that the Casita frame is C 3 x 4.1 (lbs / ft), but now I see there is also a lighter C 3 x 3.5 available. Does anyone know which one is used on a Casita frame?

If you have C 4 x 5.4, it's safe to say that's much more substantial then either of the 3" channels. How much more substantial it is I won't attempt to quantify but I think Joe Romas' post and discussion of the Casita 3" frame provides some guidance.

If you have C 4, I'd say I'm just about confident enough to follow you on the freeway.

At a safe distance anyway!
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Old 10-25-2017, 08:29 PM   #20
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Mike, I just checked my '06 SD, it's 3" C channel.
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