StandUpGuy's trailer ride

[StandUpGuy]

Better is good! Maybe it's time to get an overall weight on the trailer to see what the percentages are looking like. I'd be curious to see that. I'm wondering if it may be a bit heavier than predicted?

Its kind of looking that way.

[angib]

Sorry for the late reply - busy week, plus I had to draw the graphic below!

I should stress first that there are two different things here - where the centre of gravity is and what effect it has on trailer stability. The position of the centre of gravity is basic physics and isn't open to question (though maybe it is, over 99% of the speed of light....). On the other hand, what affects trailer stability is not a precise science so there's still plenty of 'black art' there.

This example shows what happens if you lengthen the tongue. The top case is the trailer beforehand - it weights 1000 lb with 10% of that weight on the hitch, and is about the length of a HF 4x8.

When adding 24" to the tongue in the middle graphic, I've assumed the heaviest 2"x2" tube I can find and 24" of that weighs 12 lb. It's basic maths to combine that into the (unchanged) rest of the trailer to give a new 1012 lb trailer in the bottom graphic.



The result? The extra tongue weight moves the centre of gravity of the whole trailer forward of the wheels by 1.1". However the longer tongue means that the hitch is now carrying less weight than it was before.

I don't doubt that this longer trailer may tow better than it did before, despite the hitch weight changing in the wrong direction - which illustrates that trailer stability is not a simple question of hitch weight percentage, as many people seem to think.

I am guessing the heavy weight of the porcelean toilet positioned at the absolute back has a lot of momentum on that side of the sea-saw. Obviously the toilet is stationary so is it fair enough just to load enough weight forward on the other side of the seesaw plus the extra 10-15%? I am at 142lbs tongue weight but am not sure yet of total trailer weight. My guess is about 1,000 lbs.

Now this is bad news. The worst thing for trailer stability is to have big weights at the ends - simply balancing a heavy weight in the rear with another heavy weight at the front may give a hitch weight that meets the usual recommendation, but it still makes for an unstable trailer.

What you describe as momentum is exactly right - it is actually the moment of inertia, best illustrated by the drum majorette's baton - once that starts twirling, it is not easily stopped and it's exactly the same with trailers.

A substantial increase in hitch weight may solve this stability problem, though that's not guaranteed and you may need to check if the tow vehicle hitch/receiver can take a big increase. Moving the axle is likely to be only way to make that big a change. The alternative is to remove some of the weight that's causing the problem - like giving up that porcelain toilet.

Let's say again the trailer balance mantra - heavy weights must be positioned near, or right over, the axle(s).

[StandUpGuy]

Sorry for the late reply - busy week, plus I had to draw the graphic below!

I should stress first that there are two different things here - where the centre of gravity is and what effect it has on trailer stability. The position of the centre of gravity is basic physics and isn't open to question (though maybe it is, over 99% of the speed of light....). On the other hand, what affects trailer stability is not a precise science so there's still plenty of 'black art' there.

This example shows what happens if you lengthen the tongue. The top case is the trailer beforehand - it weights 1000 lb with 10% of that weight on the hitch, and is about the length of a HF 4x8.

When adding 24" to the tongue in the middle graphic, I've assumed the heaviest 2"x2" tube I can find and 24" of that weighs 12 lb. It's basic maths to combine that into the (unchanged) rest of the trailer to give a new 1012 lb trailer in the bottom graphic.



The result? The extra tongue weight moves the centre of gravity of the whole trailer forward of the wheels by 1.1". However the longer tongue means that the hitch is now carrying less weight than it was before.

I don't doubt that this longer trailer may tow better than it did before, despite the hitch weight changing in the wrong direction - which illustrates that trailer stability is not a simple question of hitch weight percentage, as many people seem to think.

I am guessing the heavy weight of the porcelean toilet positioned at the absolute back has a lot of momentum on that side of the sea-saw. Obviously the toilet is stationary so is it fair enough just to load enough weight forward on the other side of the seesaw plus the extra 10-15%? I am at 142lbs tongue weight but am not sure yet of total trailer weight. My guess is about 1,000 lbs.

Now this is bad news. The worst thing for trailer stability is to have big weights at the ends - simply balancing a heavy weight in the rear with another heavy weight at the front may give a hitch weight that meets the usual recommendation, but it still makes for an unstable trailer.

What you describe as momentum is exactly right - it is actually the moment of inertia, best illustrated by the drum majorette's baton - once that starts twirling, it is not easily stopped and it's exactly the same with trailers.

A substantial increase in hitch weight may solve this stability problem, though that's not guaranteed and you may need to check if the tow vehicle hitch/receiver can take a big increase. Moving the axle is likely to be only way to make that big a change. The alternative is to remove some of the weight that's causing the problem - like giving up that porcelain toilet.

Let's say again the trailer balance mantra - heavy weights must be positioned near, or right over, the axle(s).

This is all very interesting and also pretty simple if you just look at it logically. Thanks for laying it out in such a clear and illustrative way.

Let's say again the trailer balance mantra - heavy weights must be positioned near, or right over, the axle

When I designed the trailer in the beginning I had all of the weight directly over the axel, including the toilet. It was so efficient weight wise I was very impressed with my planning and forethought and I began the build. Then I realized my being impressed with myself and my forethought was short lived. I had the shower pan drop down planned for where the frame of the trailer was. Because of this something had to change. After going around and around on it I decided to shift the shower pan forward and the toilet rearward as this was by a long shot the easiest way to accomodate for the trailer frame. Then after I made this decision and continued with the build I started looking on Craigslist for a toilet and lo and behold there was the most fabulous porcelain toilet. I could not resist. I bought it and then I picked it up after handing over the cash. " Man this thing is heavy!"

I think the best thing I can do is get a cheaper and much lighter toilet. I am sure a plastic toilet will be at least 40 lbs. lighter than my existing one. Probably besides removing weight from the rear pendulum I will then be able to compensate by removing weight from the tongue. No doubt the trailer will become some 70 lbs. lighter in the bargain.

[StandUpGuy]

Just reporting back to this thread as I took the trailer out on a camping trip 200 miles from home. I must say the ride with the trailer was just great. No problems at all. We even encountered some bit of wind and some rain on the drive and I half expected to find some water inside but it was dry as a bone and the wind did not affect the trailer in the least. No trailer sway at all with fast passing semis. I drove between 60 and 66 mph but on ocassion I lost track of my speed and found myself doing 75. The only towing issue at all was the slight bucking over severe moguls on the highway and dips in side roads. Even still it was very much manageable and only slight.

[KCStudly]

Fabulous!