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Old 01-26-2015, 08:41 AM   #43
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How to gain more clearance

Lol.

Ok then prove to me that my trailer is less able to keep itself upright.

If we are to play the game of unfounded contentions, I will contend my raised trailer has a lower center of gravity than your stock Silver Streak.


I will also contend that my trailer is safer than yours because your trailer is too long to be safe for use as a bumper mount tow.


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Old 01-26-2015, 09:27 AM   #44
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Sad to see that this thread has taken a predicted direction. Once again real world experience is debunked by the kitchen table engineers. I have spoken to a local heavy truck and trailer garage about the job. They have done many SOB lifts and recently a couple of new Airstreams. Quoted 3 hours of time max for my duel axle.
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Old 01-26-2015, 09:49 AM   #45
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Is a lifted truck a more stable tow vehicle? Are race cars better when lifted? If so, why?

The dynamics are of the same ilk.

There is a limit on tire adhesion. This is central.

Higher COG or lowered tire pressure mean next to the same problem for a trailer. The TT tires lose their grip sooner.

One may make a change, but it has other effects. Is that difficult?

The trade off has to be worthwhile. On that I haven't said otherwise. Quite the contrary.

As to my trailer I'd agree. And have, numerous times in the past. Just as I have also made the point that the least stable tow vehicle is a pickup.

Whenever there are weak links it is important to note them, and why. Start stacking them up together and there will be problems sooner than later. More so when the weak link is weakened further.

If you boys can't pick up a book on vehicle dynamics or read some SAE papers, it's no fault of mine.
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Old 01-26-2015, 09:53 AM   #46
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How to gain more clearance

Offer proof to counter my testimony that raising my trailer 3" has not made my trailer even slightly more unstable.

Are you simply going to offer opinion and a note to read a book on vehicle dynamics to negate my testimony?

Kind of weak Slow.

Can you even prove that the center of gravity of my raised trailer is higher than your stock height trailer?

Can you say with certainty that raising my trailer 3" raises the center of gravity more than adding a second rooftop air conditioner?

Are you also ardently opposed to rooftop air conditioners because of their detrimental effect on center of gravity?


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Old 01-26-2015, 10:12 AM   #47
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You can run around it all you want. The models exist. Is your rig granted exemption?

I really don't think you've understood what I've written. You appear to think I'm picking an argument with you, that it's a matter of right versus wrong. I'm not the one stuck in black versus white for you've not seen me specifically write that.

Would you say that GVWR is hard and fast? I've seen your posts that would counter that, that there is room on the edges. I've said the same even if worded differently. But I've also said that heavily loading a TV means far more caution as to hitch set, travel speed and braking distance.

This is no different.

Choose a pickup and one has a less safe vehicle solo or towing. Etcetera, and right on down the line for these types of choices. None are free of consequence. Models and statistics bear them out.
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Old 01-26-2015, 10:18 AM   #48
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So then you are certain that the center of gravity of your trailer is lower than my trailer?

What does the TV have to do with the apparently very narrow acceptable limits of center of gravity of a trailer?


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Old 01-26-2015, 12:02 PM   #49
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What does 'movers trailer have to do with the question of whether raising an Airstream or any trailer makes it less stable?

I'm sure J's raised trailer has caused him no problems as yet. Will it someday, somewhere make it a bit easier to sway, roll or otherwise cause a disaster? I think so, but what that point is, no one can say. I doubt J. will take it to a testing lab and find out; I wouldn't. I'm not going to wreck a trailer to prove a point. Hopefully J. has no disaster.

I also appreciate bottoming on driveways is not something anyone wants. But Airstream installs skids under the bumpers for that purpose. Hearing the sound is unpleasant, but is any harm done?

There are many factors that cause accidents—often it is combination of several at just the wrong time and place. A slight change here or there changes the total risk. Slight changes to any of the factors, or several factors, can combine in a bad way. It is very difficult to predict this in marginal situations. Everyone takes risks and is confident that they can do ok. Even objective analysis of factors such as trailer height, tire pressure, tire wear, road conditions, etc., cannot easily answer questions about specific driver skill, driver alertness, driver emotional state at any time (a bad day at home or work can mess up driver skill). In a situation where a very small thing can make the difference between an accident and no accident, the slightest thing may put you over the line. It may be towing at 85 instead of 84.5, or slightly worn tires, or the second it takes to turn down the radio, or an increase in height.

An increase of 3" is a lot. My trailer at the bottom of the banana wrap is 15" (approximately, I didn't want to be lying in the snow to get a perfect measurement; it may be lower, thus increasing the percentage difference). 3" raises it at least 20%. How much that increases risk I can't say.

We tow with a pickup though we know pickups are not the best vehicle. But I use the pickup to pick up things that don't fit in other vehicles. We don't have an SUV that can tow a 25' trailer. I don't want to spend the money to have a giant SUV to tow and still would have a smaller SUV as a daily driver; don't have a 3 car garage either. Thus we accept the risk, but try to limit it with very good tires, good maintenance, careful driving, etc.

There's no answer to the amount of risk change by increasing height unless someone with lots of money and a lab at their disposal wants to find out. There is enough data to show increasing vehicle height does increase risk, but not specifically for J.'s' trailer. Will this mean he will have an accident because of it? If he does, will the cause by increased trailer height? The future is tough to predict.

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Old 01-26-2015, 01:35 PM   #50
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How to gain more clearance

I am not going to quote your whole post, too long for me.

My belly pan sits at about 17 1/2".

The center of gravity of the trailer is somewhat higher than the bottom of the belly pan perhaps about 44" from the ground, which would mean that the center of gravity would raise somewhere less than ten percent, not even taking into account the weight of the axles and wheels which did not change.

And while you "suppose" that this will at some point cause me problems, you never mentioned having pulled an Airstream lifted three inches.

I have. If I say that there is not a lick of difference between the trailer at stock height, and the trailer at current height, do you suppose I would just fabricate this so I can impress the folks on A/F?

What if I simply found that this modification increased the utility AND safety of my trailer?

What if I find that drag plates on the rear of a trailer are a poor answer for constant dragging?


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Old 01-26-2015, 01:51 PM   #51
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So far we've had very positive reports regarding 3 inch lift from steamy1 (single axle) and J Morgan (tandem axle). I'm going to make some inquiries at a local spring/axle outfit that's been in business near me for many years (Standen's Limited :: Leaf Springs, Trailer Axles, Stabilizer Bars, Suspension Hardware, and Tillage Tools). I'll report back on their opinion and their quote.

I can't see 3" of lift being a big hazard. As others have reported, many of the SOB travel trailers don't even build with wheel wells, and they tend to travel down the highway a lot faster than I do...
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Old 01-26-2015, 02:14 PM   #52
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I have an innate ability for visualizing mechanical things in my head.

Center of gravity....

If a trailer is to be turned over by center of gravity, the center of gravity must be pushed over the outside edge of the tire. (In an arc)

This can happen in two ways, trailer tilt, or via induced g force.

If infact the center of gravity is about 44" from the ground, the trailer will need to be tipped at about 45 degrees for gravity to pull it over. And likewise, it would take a g force of at least one g to flip the trailer.

The fact that the center of gravity must be moved over the edge of the wheel in an arc, means that the three inch raise is going to influence the risk of a roll less than 1%.

If a person is going to roll one of these trailers it is because they are already in an accident, and that (at most) 1% is not likely going to make the slightest difference.

My trailer raised 3" is going to have a lower center of gravity than virtually any SOB, class A motorhome, or big truck on the road.




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Old 01-26-2015, 02:18 PM   #53
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Just got off the phone with Standens. The quote for having them do the lift work was 1600.00 all in (for modern tandem Airstream torsion axles). Ouch!

However, they've lifted many trailers over the years (a variety of brands, some Airstreams). The service foreman's opinion is that there should be no safety concern whatsoever with a 3 inch lift, given that tire rated speeds and truck towing weight limitations are not exceeded.
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Old 01-26-2015, 02:40 PM   #54
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Axles and installation, that ain't bad in my view.


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Old 01-26-2015, 03:01 PM   #55
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Quote:
Originally Posted by J. Morgan View Post
Axles and installation, that ain't bad in my view.


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The quote was for the lift kit, installation, and tax only. Far less expensive for trailers with leaf spring axles (600.00).
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Old 01-26-2015, 03:31 PM   #56
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Well that isn't as good as I thought.

It seems to me that the kits were about $200 per axle...

Sounds like he built in quite a bit of labor..


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