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Old 07-29-2015, 11:27 PM   #113
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Originally Posted by Mike Magee View Post
Dry hitch weights listed by trailer mfrs can be off by quite a bit. For one thing, they may not include LP tanks and/or battery. And they often don't include optional equipment. They are somewhat of a starting point, but it's really advisable to weigh that hitch (usually you can use a bathroom scale for FG eggs' hitch weight) before you plunk down the money to buy, and again when you are loaded for camping.

It would be very dangerous to have, say, a 2300 lb 16' Scamp loaded so as to obtain a 165 lb hitch weight. A 2300 lb Scamp should have 230 lbs or more on the hitch (some folks get away with 200 lbs, but some of those same people get some rear end wiggles). But a 13' Scamp weighing, say, 1600 lbs with a 165 lb hitch weight would be good.
I was wondering about using a bathroom scale. I have the LilBea parked perfectly level. If I lift her up and put the scale under her front wheel (what's that called?) we should get an accurate tongue weight, right?

But (just because I wonder about EVERYTHING) does the angle of the trailer affect the tongue weight? It seems like it would... say I'm a noob (which I am) and I parked her with that wheel cranked way down and she was way lower in the back. Would that make the tongue weight lighter?

Again, not planning to ever do this under any circumstances, especially when towing, but would just like to get a handle on the physics of the thing.

LP
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Old 07-29-2015, 11:39 PM   #114
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Actually, you should do it on occasion as you change your loads. In the beginning this all means that you will want to find someplace local where you can get it weighed. Truck stops, gravel yards and scrap yards are good choices/


As long as it is fairly level the angle won't have any real effect on the reading. What I do with a home scale is to make a little bridge out of two small pieces of wood that press where the people feet go, and a piece of wood across that to rest the bottom of the jack on to get a weight (That wheel will come off, it's usually just a pin holding it on.


But Again, load it up first and get a total weight, then find out what the tongue weighs.
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Old 07-30-2015, 12:50 AM   #115
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How exacting are we-- usually ---with these numbers?
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Old 07-30-2015, 07:21 AM   #116
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I can't speak for "WE", but I keep my tongue weight a little on the heavy side just in case my total weight creeps up. I check tongue weight before trips, it takes 5 minutes when I hook up. My total weight is under 1500 lbs so I verify that my tongue is over 150 lbs.


For starters you don't want tongue weight under 10% of total weight. With some experience a few have allowed this to fall to 8%, but that's not considered a good starting point for the newbie.
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Old 07-30-2015, 08:11 AM   #117
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The ONLY way to be "exact" is to take your rv to a local (for me) Co-op store or similar that sells feed etc. I think someone mentioned some truck stops may have scales as well. For $5, they weighed everything I wanted: the tongue, each wheel and total. They even gave me the print-outs and I still have them. They may not have been 100% accurate (as I'm sure there's a tolerance) but it was close enough to me and it also let me know which side of my Scamp was the heaviest... handy to know when loading it.

Just a suggestion....

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How exacting are we-- usually ---with these numbers?
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Old 07-30-2015, 08:23 AM   #118
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Originally Posted by Ellpea in CA View Post
I was wondering about using a bathroom scale. I have the LilBea parked perfectly level. If I lift her up and put the scale under her front wheel (what's that called?) we should get an accurate tongue weight, right?

But (just because I wonder about EVERYTHING) does the angle of the trailer affect the tongue weight? It seems like it would... say I'm a noob (which I am) and I parked her with that wheel cranked way down and she was way lower in the back. Would that make the tongue weight lighter?

Again, not planning to ever do this under any circumstances, especially when towing, but would just like to get a handle on the physics of the thing.

LP
I believe the trailer angle can affect your weight reading somewhat, so a level trailer is best when checking hitch weight. Ideally you weigh right below the ball socket; weighing at the jack can also throw the reading off a bit; imagine your friend holds one end of a sofa and you compare how heavy it feels for you to pick up the other end, versus if you pick it up near the middle.

Did you ever measure that hitch receiver opening to see if it's 2" across or if it's smaller than that?
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Old 07-30-2015, 11:16 AM   #119
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Originally Posted by Darral T. View Post
The ONLY way to be "exact" is to take your rv to a local (for me) Co-op store or similar that sells feed etc. I think someone mentioned some truck stops may have scales as well.
Just a suggestion....
This worked for me too. I used a truck scale for a while and then a CAT scale.

It is really nice to know exactly how the rig is sitting weight wise.
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Old 07-30-2015, 04:16 PM   #120
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I ran across a very good article on a UK website about the dynamics of caravan (travel trailer) towing.

A point mentioned there that I'd sort of intuitively understood but never really thought through was the importance of minimizing the trailer's polar moment of inertia. The closer the heavy masses in the trailer (tanks, heavy appliances, tool boxes) are to the axle, the less it's going to have a mind of its own when towing. You still have to maintain proper tongue weight for stability, but you get more stability with more mass concentrated around the axle.

If you have a 31 foot Holiday Rambler you might as well give up now, but for those of us with small FGRVs it's pretty easy to make significant changes with relatively small changes in packing. One thing I've been looking at is that the fresh water tank could easily go four inches forward closer to the axle. Not only would this gain me some tongue weight with a full tank, but it would also reduce the variability of tongue weight with water tank full or empty and would reduce the polar moment of the trailer.

Likewise, shifting the battery from the back corner up near the axle seems a logical thing to do. If you can go from two propane tanks to one, so much the better. Shifting the spare off the back on a Casita seems a reasonable move as well, and would make the trailer better looking too.

Anyway, it's another point worth thinking about as you do your packing and planning.
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Old 07-30-2015, 04:41 PM   #121
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I think that the advise to pack heavy stuff over the axle and not put heavy weights at the ends if possible, is good advice that is seen here often. However introducing terms like "Polar moment of Inertia" may only add to confusion with newbies. Say What?
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Old 07-30-2015, 04:43 PM   #122
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RB, I read the article and I agree with most of it. I am surprised he talked about the WDH's but he did. He slams independent suspension on trailers but that opinion has been proven wrong.
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Old 07-30-2015, 08:02 PM   #123
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Perhaps one of these?
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Old 07-30-2015, 10:55 PM   #124
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Perhaps one of these?
I have one. Overkill (and less accurate than a bathroom scale) for most egg hitches, but useful in weighing the trailer itself (one side at a time).
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Old 07-30-2015, 11:32 PM   #125
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I picked up a new 450# bathroom scale on Ebay for $29 w/free shipping.
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Old 07-30-2015, 11:41 PM   #126
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I have one. Overkill (and less accurate than a bathroom scale) for most egg hitches, but useful in weighing the trailer itself (one side at a time).
It is much more accurate, if you have the right scale gauge on it. Mine came with a 2,000 lb. gauge which I replaced with a 1,000. The gauge is most accurate in the middle of the range ( and easier to read ). For a 2,000 lb gauge, that would be 1,000 lbs.
If you are trying to read a 200lb. tongue weight, you really need a 500 lb. gauge. You can get the proper gauge at a plumbing supplier or order the scale with the gauge you need.
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