Who makes my axles?

[AquaMan]

Originally Posted by Herk7769

But where does it stop?

Upgrade the tires; GVWR does not change; payload stays about the same.
Upgrade the axles; GVWR does not change, BUT payload goes DOWN due to heavier axles.
Upgrade the frame; GVWR STILL does not change because the walls are not built to handle the stress of a heavier load, PAYLOAD goes down even more.

Not entirely true. Several of us Sierra 365 owners have had their axles swapped out for heavier ones and received new weight stickers from the factory, with a higher GVWR.

[itat]

AquaMan, if that's the case it suggests that at least your Sierra's chassis is designed like a flatbed with the walls contributing nothing to the GVWR. That is, they don't act as a truss contributing to the load carrying ability. They simply support themselves and anything hung on them.

[AquaMan]

Originally Posted by itat

AquaMan, if that's the case it suggests that at least your Sierra's chassis is designed like a flatbed with the walls contributing nothing to the GVWR. That is, they don't act as a truss contributing to the load carrying ability. They simply support themselves and anything hung on them.

That's most likely true, especially at 42' long. It should also be noted that the 365's were coming from the factory with 2 different axle weights, 6k & 7k, although I think they switched to all 7k's now, so the walls and framing were capable of supporting the extra weight.

[Witch Doctor]

Originally Posted by HSVBamaBob

We have a goodyear dealer right down the road from our house. Was in there a couple of days ago with my son to get an alignment on his MR2...asked the manager about RV tires. Was delighted to find out that:
1. Yes Goodyear makes RV tires
2. The tires are one of the last brands to be made in the USA!
3. They offer a replacement hazard warranty!

Goodyear RV Tires – Tire Selector

Will be getting rid of my China Bombs RSN!

Oh, forgot to mention that Goodyear offers a G rated tire - that is a lot of tire for a Ultra Lightweight (Tire Size: LT235/85R16 Max Load at 110PSI is 3750 )

BamaBob, Your rims are rated at 60 PSI on your unit same as mind, I went to D rated. Plenty of tire for your rig. Also all Good Year ST are now made over seas. I think Herk might have the last one's made in the US. That's only ST through if your looking at Lt or something they are still made in the USA I think. I bought GY a couple of years ago and run them at 60CP but they climb to 70 psi fast no problem yet......

[BigBaron]

Originally Posted by Herk7769

But where does it stop?

Upgrade the tires; GVWR does not change; payload stays about the same.
Upgrade the axles; GVWR does not change, BUT payload goes DOWN due to heavier axles.
Upgrade the frame; GVWR STILL does not change because the walls are not built to handle the stress of a heavier load, PAYLOAD goes down even more.

Not necessarily true. The axles are unsprung weight. Any additional weight from the axles will only increase the trailer weight by the same amount, not reduce the payload capacity.

[rr retired]

my salem 27rkss came with 3500lb axles. tires lasted less than 3000 miles. so after a lot of hassle lippert and forest river decided to change the springs and put 5200lb axles. so I am thinking they know there is not enough axle under most of there trailers, and just for information I weigh this camper regularly and it has never been close to overloaded. just my 2cents worth.

[AquaMan]

Originally Posted by BigBaron

Not necessarily true. The axles are unsprung weight. Any additional weight from the axles will only increase the trailer weight by the same amount, not reduce the payload capacity.

You're mistaken. Any weight added to the scale, sprung, unsprung, a concrete block sitting on the scale, will take away from your payload capacity. The GVWR is a set number.

[Herk7769]

Originally Posted by AquaMan

Not entirely true. Several of us Sierra 365 owners have had their axles swapped out for heavier ones and received new weight stickers from the factory, with a higher GVWR.

It is quite possible that they needed to do a new engineering study due to a faulty floor decision. Sometimes when a model is built, the floor supervision needs to "make a call" about shutting down the assembly line to pressing on with a substitute that "may be close." (RE: Chevy starter switches). Maybe the original spec called for the bigger axles but they were not available in time; so the limit (GVWR) for the "in stock" axles were used.

I had a 1985 Ford Ranger with manual transmission that blew the clutch 6 months out of warranty and found out the OEM clutch plate was only using the outside 1/2 inch of plate material. The correct clutch plate was out of stock, and rather than shut down the line, they substituted a smaller diameter one "that fit."

What Lippert said (when I talked to their engineers at last year's rally) was that if I had my axles upgraded they needed to do a complete engineering study to determine what was the next limiting factor to determine the new GVWR. They wanted to know if I was willing to pay for it.

Still have OEM axles...

[Herk7769]

Originally Posted by AquaMan

You're mistaken. Any weight added to the scale, sprung, unsprung, a concrete block sitting on the scale, will take away from your payload capacity. The GVWR is a set number.

Since the GVWR does not change, heavier (weight) axles will reduce your payload by definition.

[Airdale]

Just saying. And speaking from a regulatory viewpoint:

For RV trailers the GAWR is set by the trailer's manufacturer. Increasing axle load capacities has zero effect on GAWR or for that matter GVWR.

The only official hitch weight is found in the trailer's original specifications. It's value combined with certified total GAWR must equal or exceed the trailer's GVWR.

GVWR can only be changed by the vehicle manufacturer or a certified modifier.

Airdale

[cadman99]

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.

[Herk7769]

Originally Posted by cadman99

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.

[cadman99]

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.

[Herk7769]

Originally Posted by cadman99

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.

[cadman99]

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.

[cadman99]

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.

[BigBaron]

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!

[Herk7769]

Originally Posted by cadman99

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.
Herk

[OldCoot]

Originally Posted by cadman99

... 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.

[Herk7769]

Originally Posted by OldCoot

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.