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Old 02-05-2024, 04:26 PM   #1
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Question How do we inspect the frame?

Hi all,
Recommendations for this post came up when as I was surveying the condition of the 2004 T-267 I recently purchased. I've heard the term 'surface rust" a lot, but when does surface rust become a real problem? Also what else do we look for when inspecting the frame?
Thanks,
Leslie
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Old 02-07-2024, 09:30 AM   #2
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Hi Leslie,

This may help; you have two questions, both of which concern the steel frame of the camper. I’ll address each in a separate reply as both can go hand in hand with each other and not make each reply so long with the pics added.

You used the wording surface rust, which is often used when looking at older campers’ frames and even some new ones. Surface rust is a general term used many times to describe rust on the outer surface of the steel you see when looking at it.

Next comes the question of whether there are degrees of surface rust. The answer is yes; some common words to describe the severity are light, medium, and heavy surface rust. Other rust terms can be fine rust, heavily pitted rust, or heavily rusted peeling off in sheets of rust. The wording has a level of subjectiveness, and the severity is many times in the eyes of the beholder. If you speak to an RV technical person or a person who has dealt with steel corrosion, the severity may have a very different meaning than a person who is new to campers. Someone new at this may not see any paint left on the frame, and it's all brown, and they call that heavy rust. And it may or may not be as bad as sometimes this is surface rust. So, how do you sort this out, and what do you do about it?

When inspecting your camper frame for rust, how advanced it is, and whether it will create structural problems, it takes someone who has dealt with it and has some knowledge of the topic. I can give some big-picture guidelines that you can use that may help and when you need to ask for more help. When you get into questionable areas, this is the time to have someone knowledgeable about trailer frames look at them with you. I will also point out some areas of the camper frame where heavily pitted rust can be a concern.

Here are some pictures that may help quantify some of the levels of rust.

This first camper is one of my project campers, a 2004 T1950. This camper had what I declare as medium, fine rust all over most of the frame. Much of the paint was gone, and a fine rusting of the metal took over. I use the word fine, as this surface rust is in a fine grain pattern and does not have large deep pit pockets in the metal. Metal will rust/corrode differently depending on the type of metal and what it was exposed to. The camper was made in late 2003, many years before it went into storage. I am not sure what rusting it had before the storage time frame. In this case, the prior owner rented storage space outside at a dealer’s storage lot and was never moved for about eight years until I acquired it. The camper was on pavement, which was good; the rust, once it started, kept spreading with the effect of rainwater and high humidity. This rusting differs greatly from a camper exposed to road salt being towed in the northern rust belt states in early spring or winter, which is the opposite extreme.






Here is a close-up of the fine-grained, medium rust on the axles and brake plates so you can see it better during the rebuild process.

The color in the first pic is darker brown due to penetrating oil on the spring U bolts. The rust normally looks like a lighter brown color.


Here is the normal color with no oil on the steel.


Since this rust is a tight, fine grain, not deeply pitted in the high flexing areas of the frame or flaking off in sheets of rust, I made the judgment call that this camper frame is not a large structural concern from the rust. I can restore this frame by first doing an in-depth cleaning and treatment process followed by coating/painting it to prevent future rusting. The fine rust is not deep into the metal surface; consider it the looks of 150 to 100-grit sandpaper as a comparison. If I can wire brush it back to a mostly smooth metal surface, I do not have as many concerns as a heavily pitted steel in high flexing areas of the camper.

You can see here that sandpaper-looking rust was able to fall off with a scraper and wire brush treatment, leaving a smoother surface as the first step in the cleaning process. From here, you can see if there are large, deep pits better. In this case, there was none.


Here is another 2004 camper, a 2004 T317SR, another of my project campers. This camper was stored outside all its life; when we picked it up, it was on a concrete pad behind the owner’s home. They bought it new. The rusting was different on this camper; it had larger blister spots of rust than fine rust. These blisters, once removed, turned into pits and did have some minor depth to them. As you can see by the axles, the original paint is still intact, but then there are patches of blistering rusting.


A closer view


Another area at the rear left corner


After the wire brush treatment




Those blisters, once removed, showed a low level of golf ball dimple size pits. The pitting was not very deep, and their location on the frame did not concern me, so this camper frame was restorable with the cleaning and painting process.

I tried to find pictures of a friend’s 3-year-old camper frame but have had no luck finding them. I will describe what I saw, which was concerning. They had a Terry brand large slide camper that they used to take on the beach next to the ocean in lower NY. They camped there often. I looked at his frame by the wheel well and found heavy corrosion; the paint was flaking off in large chunks, exposing heavy, deep pits of rust, and the rust started flaking off in a sheet of rust. This is not good. The factory frame painting process was no match the salt air that comes off the ocean. Salts in any form are bad news to unprotected carbon steel trailer frames. Road salt can do the same thing but may be more localized since it only flies up off the tires.

The areas of structural concern with heavy rusting with deep pits or sheets of flaking rust are in these “general” areas. The camper frame flexes the most in these areas. In a layman's explanation, corrosion (rusting) with deep pits acts as a stress concentration point where a crack can start in metal, which has a high degree of constant flexing in those rusted areas. It takes a long time for the crack to start; once started and the flexing continues, the crack can spread quickly in many directions. And in extreme situations, the frame can fail.

1. In the frame area where the axles attach to the frame, the spring hangers are welded to the frame and the frame above the spring hangers.

2. Up front, where the trailer A-frame attaches to the ball coupler, the front frame header, or the main frame. The A-frame flexes often, especially when a weight distribution hitch is used.

3. On slide campers where the slide room is over part of the axle/tire area. The frame areas ahead and behind the spring hangers flex a lot due to the heavy loads and suspension, which usually do not have shock absorbers or rubber equalizers taming down the many oscillations of the frame over almost any bumps. This area is a subset of the first item near the spring hangers and the main frame itself.

The above three areas are general and apply to almost any travel trailer or fifth-wheel. Each floor plan and the way the frame is built may have other areas beyond these three, so do not consider that the list is all-inclusive.

If you ever see rusted-through holes, tiny or large, in the steel, that is a large concern, especially in the three areas above. These need to be checked out further, and extra reinforcements may need to be added to gain back enough strength so as not to have a problem later on.

While I am presenting some of the larger rusted concerns, many are not that bad and can be cleaned up and treated. That said, the longer you wait to address the rust, the harder it is to clean up. It is a very tedious task. It is always a good idea on any camper frame, new or old, to inspect it at least once a year, even if it is painted or rusted. My next reply will be on the frame inspection. Feel free to ask if you need more information on cleaning and coat/paint the frames.

If you want to, posting pictures of concerned rusted areas can help us better explain what you are seeing.

Hope this helps.

John
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Old 02-07-2024, 02:31 PM   #3
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Hi John,
Thanks so much for this detailed explanation. We haven't inspected the entire frame of our T267SR due to bringing it home the day before a snow storm. As you can see in some of the photo albums there is definitely rust there and I suspect some it falls in to category 3 but we'll have to wait until spring to thoroughly inspect it. This information is also important for us to have if and when we purchase a second smaller Sunline which we're planning on doing. Your knowledge and the sharing of it is so valuable. Many, many thanks!

Leslie
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Old 03-02-2024, 05:27 PM   #4
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Hi Leslie,

As promised, here is how to look over your trailer frame. https://www.sunlineclub.com/forums/f...avy-20776.html

The post will have sections added shortly on what caused frame damage and the repairs to correct them. I'm not sure you will need that information now, but it will be there if you find a problem.

Thanks

John
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Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC

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Old 03-02-2024, 06:12 PM   #5
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Thank you John… I’m in awe of your knowledge and willingness to take the time to share it. I just glanced at the link but see why it took a while and a great effort to write it. We are in your debt. �� Now let’s see if I can wrap my head around it to the degree it deserves! Kidding I know that the reason you write at this extended length is because you explain everything so it’s understandable! Many many thanks!!
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Old 03-03-2024, 08:27 AM   #6
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Leslie,

You are very welcome.

I have meant to get that post up for a while now; your need helped inspire me to get to it sooner rather than later.

If any questions come up, ask away.

John
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Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
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