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Old 06-20-2014, 05:15 PM   #31
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Too many assumption here ----

The problem is many of us can easily surpass the GAWR (Gross Axle Weight) because the weight of the trailer plus contents is greater than the axle(s) rating. If you upgrade the axles to carry more weight we assume the weight of the new axles will be greater but we don't know how much. Could be just larger bearings which would have a minimal effect on overall weight (GVWR). (How much difference can there be betweeen 3500lb and 4000lb axles?)

The second problem is where the weight is located. If located near the center the effect in minimal. We also assume that the trailer frame and it's structure are calculated as part of the GVRW rating.

I think if you look at any particular trailer model and the varying interior arrangements it is next to impossible to alter the structure for each different configuration. So the assumption is the trailer structure bears some of the structural integrity; but how much?

Given these assumptions (trailer is usually overloaded anyway) it would seem wiser to upgrade the axles along with the tires and possibly wheels.
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Old 06-20-2014, 05:21 PM   #32
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Originally Posted by cadman99 View Post
Too many assumption here ----

The problem is many of us can easily surpass the GAWR (Gross Axle Weight) because the weight of the trailer plus contents is greater than the axle(s) rating. If you upgrade the axles to carry more weight we assume the weight of the new axles will be greater but we don't know how much. Could be just larger bearings which would have a minimal effect on overall weight (GVWR). (How much difference can there be betweeen 3500lb and 4000lb axles?)

The second problem is where the weight is located. If located near the center the effect in minimal. We also assume that the trailer frame and it's structure are calculated as part of the GVRW rating.

I think if you look at any particular trailer model and the varying interior arrangements it is next to impossible to alter the structure for each different configuration. So the assumption is the trailer structure bears some of the structural integrity; but how much?

Given these assumptions (trailer is usually overloaded anyway) it would seem wiser to upgrade the axles along with the tires and possibly wheels.
I figure if the engineers who design and build them say it is; it is good enough for me. You, of course, can continue to believe what ever you want.
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Old 06-20-2014, 06:14 PM   #33
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Unfortunately engineers are not infallible and are restricted by cost constraints.

My comments were to indicate that all of this debate is based on assumptions and very little fact.
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Old 06-20-2014, 06:48 PM   #34
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Unfortunately engineers are not infallible and are restricted by cost constraints.

My comments were to indicate that all of this debate is based on assumptions and very little fact.
I don't know what to say. I had a very long talk with the design engineers about this very topic. I WANTED to put higher rated axles on and was willing to PAY for them.

I refused to take "not a good idea" for an answer and went up the food chain to the design team. THEY told me to save my money and buy a rig designed for a higher GVWR. They could not guarantee trying to load to a higher gross weight would not result in slide/window/door opening cracks due to a combination of frame flex and wall movement.

THAT was little enough "fact" for me.
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Old 06-20-2014, 08:05 PM   #35
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I understand all of that. But the fact remains these same engineers (and probably marketing folks) based on what we know as fact are putting trailers on the road, that by their very nature, will be at least overloaded at the axles. No one expects to buy a 27ft trailer and not be able to load it with the things they need to camp. (this is not even counting the potential water weight that is possible)

I possess one of those. If I load it as everyone suspects to 1000lbs or over I have exceeded the capacity of the axles and tires. Many folks on this forum pay attention to things like that but there are thousands of others who don't have a clue. I would happy to upgrade to 4000lb axles with "d" rated tires even if I sacrificed a few pounds in GVRW.

Frames are designed to flex - bonded fiberglass panels are not. If you think about it those with springs are better than those with the "torque" axles. With springs the total load is spread from the front to rear spring perch. The torque axles are a "point" load directly over the axle - much more chance of frame flex loaded or not. By the way more unsprung load (axles) will have nothing to do with frame flex.

But then again I don't think you should be towing a 9000lb trailer with a 1/2 ton truck.
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Old 06-20-2014, 08:22 PM   #36
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Now my facts. I own a 30ft Rockwood Ultra-light. It's posted GVRW on the trailer is just about 9300lbs. Axles are 3500lbs. At this point it weighs 8800LBS total with about 1775lbs on hitch pin. I am right at axle capacity but around 500 lbs short of GVRW. I can load another 500lbs if it is directly over the pin which is right in the middle of the bed. Explain that to the engineers.
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Old 06-21-2014, 05:13 AM   #37
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I guess that when axles lose their camber and wear out tires because they are so close to their limits, it's ok. I've seen a thread or two about that...
A lot of lawyers are involved, so they have to be careful. Get a person with common sense involved and you get a totally different answer.
Herk - where did you get those pics? That's nasty!
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Old 06-21-2014, 07:22 AM   #38
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Now my facts. I own a 30ft Rockwood Ultra-light. It's posted GVRW on the trailer is just about 9300lbs. Axles are 3500lbs. At this point it weighs 8800LBS total with about 1775lbs on hitch pin. I am right at axle capacity but around 500 lbs short of GVRW. I can load another 500lbs if it is directly over the pin which is right in the middle of the bed. Explain that to the engineers.
MAN! I really HATE it when the power quits in the middle of a long post.
So, from memory...

I think you have the wrong axles on your camper. Could you post your yellow sticker and a photo of your axle tags? Mine are here. Your GVWR looks to be 9250 pounds from the data I have been able to find on the internet.

My camper has a GVWR of 9129 pounds and has two 4,000 pound axles as OEM.

As you state, your axles (as you have them loaded) are over loaded by an average of 25 pounds. This sounds like no big deal until you realize the rear axle typically carries more load than the leading axle in most 5th wheels.

I would take that camper to the scales and try to position the camper's axles on 2 plates. It is hard to do since they are so close together.

I would also contact the manufacturer (Rockwood division) to see if there is a "silent" axle recall on your camper.

If I had your axles, I would be complaining too.
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Old 06-21-2014, 08:06 AM   #39
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... If you think about it those with springs are better than those with the "torque" axles. With springs the total load is spread from the front to rear spring perch. The torque axles are a "point" load directly over the axle - much more chance of frame flex loaded or not...
Not true, torsion axles are mounted on a 2 x 4 steel tube frame that spreads the load out on the frame. I like that better as the spring mounts are point loads and welded directly to the frame I beams.
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Old 06-21-2014, 10:46 AM   #40
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Not true, torsion axles are mounted on a 2 x 4 steel tube frame that spreads the load out on the frame. I like that better as the spring mounts are point loads and welded directly to the frame I beams.
Thanks OC, I had mentioned that in my "lost" post.
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