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Old 10-03-2019, 03:38 AM   #101
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Then in Europe:


Max speed on highway in the Netherlands for trucks and heavyer TV-Trailer combinations si 50mph, and sincel 10 years or so the lighter TV-Trailer combinations 55 mph.
In other country's here 55mph for all, and in France ( dont know the exact rules) no speedlimit for personscars with trailer.


So I have driven with my 1300kg/2850lbs? traveltrailer behind, about max 75 mph on the french toll- highways..


Now European Trailers have low weight on towbar, max allowed is 10% for a middle axle trailer, and minimum only 1% . I learned that in America its max 15% for a middle axle trailer( so no.t 5th wheeler) and minimum 10%


I write this , because this towbarweight has influence on the stability , so max speed to be able to drive savely.
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Old 10-03-2019, 05:16 AM   #102
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”Originally Posted by out of sight View Post
Correct. The oscillation type of sway that you mention is something that every trailer will experience once it reaches a certain speed (the critical speed). The critical speed is mostly dependent on the distance from the the trailer wheels to the trailer center of gravity. If the center of gravity is very close to the wheels then the trailer will become unstable at a very low speed. If it is far from the wheels and closer to the hitch then the trailer will not become unstable until a very high speed. Most trailers are designed so that, if loaded properly, they won't sway until a very high speed. Manufacturers give the instruction to always keep a high load on the hitch, usually at least 8% or 10% of the trailer weight, since this is convenient measure of the center of gravity distance. If you maintain that hitch load your trailer will not become unstable at highway speeds. The critical speed will be well over 100 MPH. However if you have zero or a very low hitch load your trailer will become stable at a very low speed. ”

What OOS posted is fact except for maybe the 100mph critical speed. As is true on nearly all RV forums those that are giving out advice don’t understand towing dynamics and the physics behind it.
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Old 10-03-2019, 08:47 AM   #103
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Originally Posted by out of sight View Post
I tow my 28 on the ball up to 85 MPH and I don't have the slightest bit of sway. So why does mine not sway and yours sways?
Hi

Buy one and see

It most certainly does sway and the anti sway braking on the Ford is quite a experience when it cuts in. It is *not* anything you want to have popping up on a regular basis. The simple answer is that there is way more to this than just tongue weight or truck weight. The more complex answer is that the Classic has a lot of "weight up high".

One other detail, when I'm pulling it on the ball, the tanks are empty. Filling them helps stabilize things. It has zero impact on the tongue weight (tanks are over the trailer axles) and actually makes the trailer heavier. Tongue weight as a percentage goes down when you fill the tanks.

======

In addition to Texas, Montanna has some pretty high speed limits. If the 85 MPH limit does not apply to trailers, that point is poorly documented on their signs.

Bob
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Old 10-03-2019, 09:30 AM   #104
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Originally Posted by uncle_bob View Post
Hi

Buy one and see

It most certainly does sway and the anti sway braking on the Ford is quite a experience when it cuts in. It is *not* anything you want to have popping up on a regular basis. The simple answer is that there is way more to this than just tongue weight or truck weight. The more complex answer is that the Classic has a lot of "weight up high".

One other detail, when I'm pulling it on the ball, the tanks are empty. Filling them helps stabilize things. It has zero impact on the tongue weight (tanks are over the trailer axles) and actually makes the trailer heavier. Tongue weight as a percentage goes down when you fill the tanks.

======

In addition to Texas, Montanna has some pretty high speed limits. If the 85 MPH limit does not apply to trailers, that point is poorly documented on their signs.

Bob
I would suggest that truck weight is one of the reasons yours sways and mine doesn't. My RAM weighs 110% of the trailer weight. Your truck is likely around 80% of trailer weight.
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Old 10-04-2019, 07:15 AM   #105
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I would suggest that truck weight is one of the reasons yours sways and mine doesn't. My RAM weighs 110% of the trailer weight. Your truck is likely around 80% of trailer weight.
Hi

Ok, so why is the system *more* stable when the trailer weight goes up?

Bob
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Old 10-04-2019, 09:35 AM   #106
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It's not. The system is more stable when the tongue weight % goes up. Unless the tongue weight is so great as to lift too much weight off the front wheels of the tow vehicle.
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Old 10-04-2019, 07:58 PM   #107
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Hi

Ok, so why is the system *more* stable when the trailer weight goes up?

Bob
The purpose of setting a TW % is to set the longitudinal position of the trailer COG. Having it forward of the the axles centerline is important for stability. What you have demonstrated is the importance of centralized loading around the trailer axles/COG. The COG shifts rearward and TW% goes down some but more importantly because of where the mass was added it effectively lowers the yaw inertia of the trailer. This is the secret to lowering TW and maintaining stability. I have a 8k lb SOB trailer that normally runs 11.6-12% TW and is remarkably stable because the water tank is right over the axles, I centralize my loading as much as possible, the heavy slide out and kitchen are right at the axles. This type of loading is easy with a cargo trailer but can be done to some degree with a RV TT enough to make a difference. Less tongue weight and more stability means less WD can be used, that’s a win-win situation.
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Old 10-05-2019, 07:36 AM   #108
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Originally Posted by out of sight View Post
It's not. The system is more stable when the tongue weight % goes up. Unless the tongue weight is so great as to lift too much weight off the front wheels of the tow vehicle.
Hi

Except it most certainly *is* more stable in the case of a Classic. I've demonstrated this a number of times. Others have also noted this, and mentioned it.

Try one and see ....

Bob
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Old 10-05-2019, 10:40 AM   #109
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I would agree with profxd's explanation. I would also look into other variables such as tire cornering stiffness, which increases with load.
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Old 10-05-2019, 05:24 PM   #110
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Since I am the original poster in this thread I am re-threadjacking it :-) After thinking about it and considering that at Christmas we will be towing for two weeks with grandkids (more weight) we opted to buy a 3/4 ton truck. I had the hitch re-set to account for the taller truck and hooked it up today to try it out. It is a tad nose down but not bad. The weight distribution is nominally okay (the front lifted 1/2" without the bars on the Equalizer hitch, and came back halfway when they were added). I will head to the scales and tweak as necessary. My wife loves the Marsala interior and the dog is fired up for another road trip next weekend.

Note that my payload has increased 600 lbs so I should be fine even if I put a cap on it.

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Old 10-05-2019, 06:35 PM   #111
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That’s a nice looking rig! Enjoy.
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Old 10-06-2019, 01:09 AM   #112
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With the picture, you answered my question about one or 2 axles.

What I see is a pretty low towbar, so front of TT lower then back.

This gives more weight on front axle then rear.
So higher pressure on front axle needed. Now genenerally same pressure prescribed on the both axles.

But dont try to change this, then even more weight on towbar, so you then have to tighten the WDH even more.
And with that more weigt on front axle of TV .

Only dont go driving offroad with the combination ����
Then towbar will hit the underground to often.
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Old 10-06-2019, 08:22 AM   #113
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I would agree with profxd's explanation. I would also look into other variables such as tire cornering stiffness, which increases with load.
Hi

But it in no way agrees with your contention that tow vehicle weight is the key or that tongue weight is a big part of it .....

Bob
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Old 10-06-2019, 09:17 AM   #114
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Its not just my contention. Any trailer manufacturer will tell you that.
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Old 10-06-2019, 11:33 AM   #115
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Originally Posted by DewTheDew View Post
Since I am the original poster in this thread I am re-threadjacking it :-) After thinking about it and considering that at Christmas we will be towing for two weeks with grandkids (more weight) we opted to buy a 3/4 ton truck. I had the hitch re-set to account for the taller truck and hooked it up today to try it out. It is a tad nose down but not bad. The weight distribution is nominally okay (the front lifted 1/2" without the bars on the Equalizer hitch, and came back halfway when they were added). I will head to the scales and tweak as necessary. My wife loves the Marsala interior and the dog is fired up for another road trip next weekend.

Note that my payload has increased 600 lbs so I should be fine even if I put a cap on it.
It looks to me like the rear of your truck is too high up, i.e., there is not enough load on the rear axle. Bear in mind that you have a 1000 lb diesel engine sitting over the front axle and when the truck is empty the front end is too heavily loaded and the rear end is too lightly loaded. Dropping 1000 lbs of weight on the tongue will compensate for the 1000 lb diesel engine. I would suggest that you strive for equal load on both axles to improve stability.
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Old 10-06-2019, 11:49 AM   #116
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It looks to me like the rear of your truck is too high up, i.e., there is not enough load on the rear axle. Bear in mind that you have a 1000 lb diesel engine sitting over the front axle and when the truck is empty the front end is too heavily loaded and the rear end is too lightly loaded. Dropping 1000 lbs of weight on the tongue will compensate for the 1000 lb diesel engine. I would suggest that you strive for equal load on both axles to improve stability.
I think that is an illusion of this particular photo and the shadows. I measured front and rear heights before hitching, hitched without WD, and hitched with WD and the final numbers indicate a slight nose up attitude of the truck when fully hitched compared to unhitched. Of course I will weigh it but did not have time yesterday (the nearest scale is almost an hour away).

But I appreciate the comment and will be sure to get this properly set soon. Note that also I will have several hundred more pounds in the cab and bed of the truck when I travel.
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Old 10-06-2019, 12:01 PM   #117
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I think that is an illusion of this particular photo and the shadows. I measured front and rear heights before hitching, hitched without WD, and hitched with WD and the final numbers indicate a slight nose up attitude of the truck when fully hitched compared to unhitched. Of course I will weigh it but did not have time yesterday (the nearest scale is almost an hour away).

But I appreciate the comment and will be sure to get this properly set soon. Note that also I will have several hundred more pounds in the cab and bed of the truck when I travel.
I think what he is getting at is the attitude of the trailer, which appears to be much lower at the front. It is important to have the trailer as level as possible once it is loaded and hitched up. This ensures that you have as close to equal weight on the front and rear trailer axles. The way your current setup looks, you will have considerably more weight on the front axle of the trailer than the rear, which is not a good thing.
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Old 10-06-2019, 12:06 PM   #118
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I think what he is getting at is the attitude of the trailer, which appears to be much lower at the front. It is important to have the trailer as level as possible once it is loaded and hitched up. This ensures that you have as close to equal weight on the front and rear trailer axles. The way your current setup looks, you will have considerably more weight on the front axle of the trailer than the rear, which is not a good thing.
Yes, as I noted the front of the trailer is down some (though he mentioned the truck specifically). I will get it sorted as it is important to me to have everything set properly. This was just the first cut and test to make sure it wasn't too unreasonable to tow the rig to a place that can help to sort it out. Thanks!
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Old 10-06-2019, 12:10 PM   #119
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I was actually talking about the attitude of the truck. But whatever you decide to do about how your truck axles are loaded, in the end you must always have a level trailer. That will ensure your trailer axles are evenly loaded. This will require adjusting your hitch ball height.
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Old 10-07-2019, 03:48 PM   #120
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Now I judge the picture again, I see that the underground is going down, at back of trailer.

So your TT is probably totally level, and so more equall weight on the axles.
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