Designing toy hauler for balance and tongue weight

[brianjonesphoto]

I’m getting closer to pulling the trigger on a 8.5x16x7.5 trailer. I know that we will use it for a camper when not hauling toys too. Since I’m in the design and layout phase what should I consider so tongue weight doesn’t get out of control. I’m not planning on grey/black tanks and don’t know if I’ll go with built in water storage to start with. Tent camping we usually use 3-7gallons of water in 2 nights.

I will likely do a pair of 6v batteries for a basic electrical system.

The toy hauler capability somewhat relegates me to keep most of the infrastructure at the nose. That is what worries me as I don’t want to design myself into a nose heavy trailer.

Thanks.



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[fishboat]

You might do a simulation.

A) Measure the tongue weight with the trailer empty.

B) Measure the tongue weight with only your expected load motorcycles, atv..etc.. in it

C) Use steel weights, concrete blocks, 5 gallon pails of water ..whatever you have and load the trailer where you expect the finished trailer loads to be and check the tongue weight. If you add the various weights in their locations separately and determine the tongue weight for each one you can determine the incremental tongue weight added by each weight in each location.

Example 1: From above B - A = tongue weight added from motorcycles, atv..etc..

Example 2: Say your cabinets and equipment you plan to build/load into the nose of the trailer will weight 150 pounds. Load 150 pounds(water in pails, concrete blocks, people..) in the trailer nose and measure the tongue weight. This tongue weight minus A above (empty trailer tongue weight) = the tongue weight contributed by the 150 pounds(it'll probably be about 75 pounds).

Tongue weight for (cabinets & equipment in nose) + (atvs or motorcycles) + (base empty trailer) is then (tongue weight A above) + (tongue weight Example 1) + (tongue weight Example 2).

This shows the results of my simulation(after having the same question your asking now): viewtopic.php?f=50&t=70942

Note the "incremental coefficient" in the spreadsheet image, bottom line. This number is essentially the fractional portion of weight added to the tongue due to each incremental weight. With respect to the battery column, 49% of the battery weight added to the trailer nose ends up on the tongue. If you add weight behind the axle(a generator, spare tire..etc..), it'll reduce weight on the tongue.

There are online calculators that may offer some guidance..the problem there is you really have no idea if what your calculating is reasonably correct. If you do a simulation, you'll be pretty much on and know where you stand..before you spend time and money and potentially make errors.

[Daz7]

On my build I'm keeping a very good eye on both weight and drawbar weight.

Purchased one of these Caravan weight scales and am weighing the build as I go, if I need to I can move things around to compensate. You really need 10-15% of the overall weight as drawbar weight

[RJ Howell]

I like this site to take some of the guess work out of it. https://mechanicalelements.com/trailer-axle-position/

I like spreadsheets, once the math has been worked out. All as inches and pounds.

Forward of the axle


Aft of the axle.

[jwhite]

I am no expert but my trailer has to be very front heavy because my kitchen and bathroom are in the front along with 20 gallon water tank and 2 golf cart batteries, but I haul a golf cart and the weight over the trailer axles somewhat balances it out.
I notice one time that the trailer wasn't pulling right and kind of was fishtailing so when I stopped and looked I saw the ropes I used to tie it in place had broke and the golf cart had crashed into the kitchen and all the extra weight made it out of balance. the kitchen area and shower were so wacked out of place I had to tie a long rope and hook it to the golf cart and snatch it back in place but was never exactly right.
I now use straps and pull the cart inside just enough so most of the weight is in the rear.

[Tomterrific]

I haul motorcycles with a variety of trailers. I look at the crankshaft position and the center of the wheelbase and make sure it is in front of the trailer axle.

In the case of designing your long trailer, if you plan to haul two motorcycles what about one in front of the other? I suggest this as the trailer will be long enough and the balance would not change no matter hauling or not.

Tt

[McDave]

Try this.....
https://www.engineersedge.com/calculato ... alance.htm
This can be helpful. Just enter your numbers where the red numbers are, then update. The program will do all the math for you.
I used it when building my toy hauler. Helped a lot. Try to keep the heaviest load, probably the toy, centered or neutral over the axle.
I use my 25 gal fresh water tank as ballast. It is mounted under the floor behind the axle. The black tank is just forward of the axle. Rooftop A/C over the axle. Harley with motor over the axle. Generator on tongue, batteries and propane in the nose. You want to shoot for 15% of total weight on the hitch. For me it is about 400lbs. and it tows nice when loaded.
Good luck!

McDave

[skooter69]

I didn’t use a calculator, so maybe I got kinda lucky. But when I designed my 7x16 I tried to distribute as much of the static load as I could evenly front to back (cabinets, etc). The electrical control system, air conditioner and batteries are at the front - providing extra tongue weight for a perfect ~12% of my gross weight. The water tanks are over the axles, and so is the motorcycle when I haul it. So regardless of water amount or whether I have the motorcycle, it’s nicely balanced with the right amount of weight on the tongue. It pulls great - no sway bars needed.