Questions on adding to the rear of Scamp 16 - Page 2 - Fiberglass RV

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Old 07-03-2016, 06:03 PM   #15
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Name: Wayne & Barbara
Trailer: Parkliner
Posts: 670
Originally Posted by widgetwizard View Post
A forward center of gravity is inherently stable.
It naturally inhibits sway.
I was actually looking for some science that more than 15% tongue weight is bad.
I cant believe that it is bad - how much tongue weight do semi-trailers have - 50%? They seem to get along just fine.
A Semi trailer and tractor have a totally different geometry. The fifth wheel pin is located above and slightly forward of the tractors tandem axle center. Those tandems are built to carry a heavy load. And it does not take weight off the front steering wheels. Same for fifth wheel trailers.

A tow behind trailer connects to the TV some distance behind the rear axle. the hitch weight causes weight transfer off the font wheels to the rear wheels. Too much and you lose traction in front. Especialy bad for a front wheel drive TV.

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Old 07-03-2016, 06:11 PM   #16
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Name: Wayne & Barbara
Trailer: Parkliner
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Originally Posted by Teal View Post
Greetings again,

I am considering adding a small cargo carrier to the rear of my Gem with a bike rack attached. I've read some posts that allude to negative reasons for adding to the rear.

What is the weight or tongue ratio issue associated... I am not an engineer, but know that this is the case, just trying to understand, and learn about what others have done to see if what I am planning would be OK.

Wouldn't some weight in the rear offset the tongue weight? how much would be OK?

Thanks so much for your experience and recommendations.
A cargo box and/or bicycle may hide your tail/stop/turn lamps from view to those behind you. Add high mounted LED lamps to supplement, or mount them on the cargo box.
A hitch receiver should have a rectangular tube or channel iron extending forward under the trailer to one of the cross members ahead of the rear bumper.
Compensate for the added rear weight by shifting inside stuff forward., keep you water tank empty - if it is behind the trailer axle - for instance.

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Old 07-03-2016, 07:55 PM   #17
Name: RogerDat
Trailer: 77 Scamp 13
Posts: 3,104
Those extended bike racks provide a lot of leverage. The bikes weight is essentially pulling down on a pry bar. That prying strains the attachment to the trailer and the joints of the rack/storage fixture. The further back it extends the more leverage it has.

Going straight up from bumper with rack will probably work best. Some folks have put a storage container on the tongue with good results. Norm added some plastic bins under the trailer for storage, sort of like those ones that go under a bed.
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Old 07-03-2016, 09:04 PM   #18
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Name: bob
Trailer: 1984 u-haul ct13; 1996 Casita 17 Spirit Deluxe; 1946 Modernistic teardrop
New York
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[QUOTE=RogerDat;596262]Those extended bike racks provide a lot of leverage. The bikes weight is essentially pulling down on a pry bar. That prying strains the attachment to the trailer and the joints of the rack/storage fixture. The further back it extends the more leverage it has.

Many people don't think of the leverage principle. Trailer bounce adds to the effect. I prefer the type rack where the bike wheels set on the rack and a hook clamps over the bike upper frame tube. I think this type rack may reduce some of the leverage. Swagman makes a rack of that type that is rated for trailer rear use.
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Old 07-03-2016, 09:52 PM   #19
Name: Jim
Trailer: Scamp
Posts: 51
I agree with the info and advise given. I had my own experience with balance and pendulum effect with my 2014 Scamp side dinette plan. Grey hair ... absolutely! With or without rear bike rack. Things like rear bike rack or filling my Dual fresh water tanks multiplied my problems. I've had a bike rack break and damage my bikes.
There are a variety of things I have done that brought the pendulum effect under control.
1. refrain from carrying water in fresh water tanks unnecessarily (instead carry portable water jugs in front of trailer when necessary)
2. Mount bikes on back of tow vehicle
3. Add friction type anti sway hitch attachment (I swear by this)
4. I added shock absorber kit from Orbital Machine Works in Texas. (this has more to do with reducing bounce on multiple bumps than the actual pendulum effect)
The result is safe trouble free towing where I am not having to anticipate trailer behaviour on downhill breaking, unexpected humps in the road at highway speed, turbulence from passing Semis. The friction type anti sway attachment should be a part of any formula you use. The result is total stability and ease of control.
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Old 09-01-2016, 02:31 PM   #20
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Name: Mike
Trailer: Escape 21 & Jeep GC 5.7 (Previous 2012 Casita FD17 & 2010 Audi Q5)
Puget Sound, WA
Posts: 704
That's a great post! I wish everyone who tows would see that video. It wonderfully illustrates the practical effects and results of a complex dynamic system (comprised of a tow vehicle and trailer operating in changing environmental conditions) that is very difficult to actually understand.

I say this with confidence because I don’t fully understand it myself.


I seem to recall that Bob Miller mentioned having difficulties when he swapped out the stabilizers on his little Hunter Compact II for slightly heavier ones. What seemed like it would be a trivial change turned out to have a definite impact and made the rig more sway-prone.

All of the parts, tow vehicle, trailer, and the loading, play a part in stability or instability of a towing combination. Rules of thumb are generally useful, but not always. As an example, I don't foresee a problem if I were to pull a 1,000 trailer with a 25% or even 35% tongue weight (250 to 350 lbs) on my tow vehicle, provided the trailer and load geometry were suitable and the frame sufficiently strong.

I was recently towing for a ten day trip with up to 420 lbs on the hitch. I travelled over the Cascade Mountains, several other mountain passes, and also drove through some "spirited" winds along the Columbia River on two different days. I never once felt any instability, even when I tested the stability at higher speeds and with a few judiciously applied waggles of the steering wheel.

(I'm not saying that I will continue with 420 lbs on the hitch; it was more a result of not taking the time to closely monitor my hitch weight due to the difficulty of setting up the board-and-bathroom-scale approach. I will now invest in a tongue scale so that I can monitor this more closely.)

And yes, the dynamics of a bike rack and cargo carriers bouncing around on a rear-bumper mount are generally terrible; the movement multiplies the forces greatly. And, locating a load so far from the axle and also behind the trailer axle are both negative factors.

For those like me who still haven’t had enough of learning about this stuff, here's some more interesting information:

"Caravan makers typically recommend tow ball weight as a percentage of the caravan's weight. But caravan dynamics are such that it cannot be."


- "Character is what you do when nobodyís looking." -
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