tongue weight : real wt. vs. projected weight

[KCStudly]

Build it for yourself and your needs. We don't have a problem with it if you don't!

As always, just trying to be of some help.

[working on it]

Build it for yourself and your needs. We don't have a problem with it if you don't!

As always, just trying to be of some help.

KC- I appreciate the interest, and of course, the ideal way to fix the problem, is to move the axle back. But, at this stage, I would have to find a shop willing to do so, since my pal is unable to do it at this time. I never learned to weld! Like I've said before, I bolt together stuff. And while it is being done, I might as well upgrade the axle to a stronger one. Hundreds of dollars, whereas I might be able to do it my alternative way for much less, with materials I already have on hand. Maybe not. Still, in the long run, I will most likely do so later.

[48Rob]

Guys-I really do appreciate your concern, honestly, but I have to do this in my own perverse out-of-the-box way. I never wanted a "show" trailer, nor cookie cutter design, and wanted the bones and repurposed hardware and improvisations to stick out, by intention, from the first.

I can sure understand trying to be different, innovative, not following the crowd.
Nothing wrong with that.

I'll be interested to see what outside the box solution you come up with.
Of course you can use band aids like sway bars, etc. but then you'd be following the crowd again...

Quite a few trailers in Europe have that same ungainly stance, where the wheels are pretty much in the middle of the body, leading to an unstable trailer if every last ounce of weight isn't in the exact correct spot.
It works...though many can't drive at a reasonable highway speed because they are so close to the edge (of being unstable).

Building a safe, balanced, stable foundation for your trailer doesn't really qualify as a "show trailer".
I suppose you could call a proven (axle placement) design to be cookie cutter, but then if it is, we all are...

Please keep us updated!

Rob

[working on it]

Quite a few trailers in Europe have that same ungainly stance, where the wheels are pretty much in the middle of the body, leading to an unstable trailer if every last ounce of weight isn't in the exact correct spot.
It works...though many can't drive at a reasonable highway speed because they are so close to the edge (of being unstable).
Rob

Rob (and all)-I hope I've not alienated anyone with the "cookie cutter" remark...it wasn't detrimental in any way, I just wanted to build a bolt together trailer with a sloped front end (in the wind shadow of the TV), and none of the plans I saw were exactly like that. Besides, I wanted a thick walled trailer, that could resist hail, branches, and road debris (the standard thin bent ply front made me wary). Just my preferences. But, as to "ungainly stance", maybe it is outside the norm, but was actually within the guidepoints Angib posted in his Trailer Balance treatise: Trailer Axle Position 'Rules of Thumb'
Here are some really simple 'rules of thumb' that you can apply:

Axle Position, % of body length
(C/A in diagram above) Reasons to pick this value:

40% (eg, 38" from back for 8ft body)
A reasonable compromise value for an average teardrop.

45% (eg, 43" from back for 8ft body)
Tongue box.
Light or no galley.
Minimum safe hitch weight wanted.

35% (eg, 34" from back for 8ft body)
Well-equipped/heavy galley.
Long tongue.
Heavier hitch weight wanted.

Please remember that picking the right axle position does not mean that the trailer can be loaded without any thought - how it is loaded will determine the hitch weight, as much as where the axle is. I chose to replicate the middle road, as best I could 45% Always intended for a tongue box, a light galley (the original plan was for a counter space over the battery and generator, with no heavy cabinets > a weight trade-off). The galley ended up heavier than planned. A minimum safe hitch weight was intended (aimed for 100lbs/1000total, not attained!). The actual measurements were quite close to Andrew's 45%: 44.75" from hatch rear to wheel centerline, 53.75" from centerline to end of front wall (46% rear/54% front, but without tongue box or spare tire yet added forward) almost on the money. Using the calculations on the balance sheet, I thought I could use a toolbox instead of a tongue box, to save weight, but I'll have to move the battery forward as originally planned, and place it there. The pictures in my gallery do not give the true overall impression, and it does look a bit "ungainly". But on measurement, and with a few corrections, the 45% or better can be achieved. And, lest we forget, the tongue itself; it was intended to be longer than needed, heavier than needed, and stronger than needed. It was to lend itself to creating the balance desired. It is 42" from front of the trailer wall to the hitch ball, of 3"x.187" square tube, with an extra 2.5 feet under the front to tie in 3 crossmembers. This was planned as a counter-balance for the extended rear ( I just over-loaded the rear). Once I rebalance the systems, I'll pull it out of the garage to get a full side-view and you'll see the balance of form. I also want to address the sway-bar issue: I've pulled trailers perfectly balanced, and some completely wrong, and traveled over smooth roads and those with dips and chugholes; I've found that using swaybars and/or weight-distributing hitches may be considered band-aids for some, but I've learned to never leave home without them. They turn marginal into manageable, and I never worry about the ball/coupler parting ways (happened to me once, bulldog coupler even!). The weight-distributing system was always part of my plan, the sway bar not so much. So the work goes on....If all corrections fail, then I'll eat crow, buy a 5x8 welded trailer, and unbolt the HHRv superstructure from the frame, and transfer the flag.

[pchast]

It seems you have a good outlook about it.
Soldier on!

[48Rob]

Rob (and all)-I hope I've not alienated anyone with the "cookie cutter" remark...it wasn't detrimental in any way, I just wanted to build a bolt together trailer with a sloped front end (in the wind shadow of the TV), and none of the plans I saw were exactly like that. Besides, I wanted a thick walled trailer, that could resist hail, branches, and road debris (the standard thin bent ply front made me wary). Just my preferences. But, as to "ungainly stance", maybe it is outside the norm, but was actually within the guidepoints Angib posted in his Trailer Balance treatise

No worries here!
I didn't take it in a bad way at all.
I just wanted to point out that at some level, a good frame/axle/balance design, by virtue of its success, falls into the "cookie cutter" category.

My ungainly stance comment, in case it was misunderstood, was not about your trailer body design, but about the appearance of the axle location when compared to the frame length as viewed with knowledge of how unstable a trailer can be when fitted out this way.

Andrew and the other engineers here are able to work the numbers down to such small fractions that they can perhaps "walk the line" with regard to success or failure. While testing the water is sometimes an enjoyable practice, walking on a knifes edge is too risky at 75 miles an hour on the highway, so I err in favor of having a bit of leeway.

I hope it all works out for you as planned, and in the end, I'll learn something new from your experience I can use on my next build.

Rob

[working on it]

UPDATE-first tow/weigh-in/handling test combo day-Well, I finally got it weighed. 1280lbs; about what I expected, heavier than hoped for...not the actual travelling weight...subtract 12lbs (removable jack) add 100lbs (water jugs)+60lbs (loaded ice chest)+10lbs (side tables to be stored inside); total actual travelling weight will be 1280-12+100+60+10= 1438lbs (looks like a truck tow will be needed, not my HHR or Cobalt. I didn't load it up as I intend to use it, because I wanted to test its' handling under worst-case tongue weight conditions. So the 1438lbs is the corrected weight to the photo shown here: By the way (weigh?), even though there was only 45lbs tongue weight (since the trailer was 6" nose-up, 60lbs tw when level, even without the 170lbs going inside the cabin), and the tires at 50lbs psi, it towed perfectly at all speeds on twisting roads and over bumps...go figure! 4'x8' 1438 lbs.

[working on it]

After the weigh-in last weekend, and though I towed it with no problems despite trying to test too light tongue weight conditions and under-inflation, I still wondered why it didn't match my balance sheet. I re-weighed some items, re-estimated some others, re-measured some distances involved, and checked the much adjusted format. As I made small adjustments to the database, I saw it moving closer to what the true scale weights came out to. And then I placed the items I did not take to the weigh-in into their allotted spaces, and at their true weights, and the balance sheet came to match the final adjusted travel weight I observed. 1438lbs. Some weights are rounded off, and some have been simulated with substituted (actually weighed) items. But so close, I couldn't believe it. The trailer weighs what the spreadsheet predicts, with a minor variance as to tongue weight, probably just my makeshift tongue-weight scale.

balancefinal adjustedresult after weighin 8-17-13.xlsx

(71.79 KiB) Downloaded 21 times

I have made many mistakes in my build, and did it differently than advised, and when I saw the error of my ways...it was already a done deal, and I made some adjustments along the way to keep it viable. I really needed another foot of front overhang, a foot less of rear overhang, and probably less plywood thickness. But its a strong trailer, and that's what I wanted most. I wouldn't have been able to do it alone, thanks to my friend for his help for a year, and to everyone who added something on the forum, and especially to Andrew for the spreadsheet that helped me get this close to my goal. Update 6/21/14: much later (the weight of the trailer has grown to 1767.5lbs), because>>>after installing a larger tonguebox (more to my original plan than box #1) and thus shifting more weight forward (again, like I originally planned) the balance changed favorably in favor of the conventional wisdom. And, after I replaced the original axle, spring hangers, springs, and installed brakes...after reinforcing the frame with heavy steel...then added more steel with bumpstop/spring substitutes added, the weight balance has changed again. 10.3% tongueweight @ 182lbs.

new cg.jpg (83.59 KiB) Viewed 81 times

As I keep the trailer in a state of continual change, these figures are not set in stone, stay tuned....