Cracked Frame

[Bill]

JimWilly -

Mike is right - I think the detachable wheel is supposed to be standard equipment. Did you look in the storage compartment in the back bumper? The wheel is clumsy and grubby, so that is where it often gets stowed.

Bill

I have a wheel for the jack - without it I wouldn't be able to store the TM on the back patio for the winter. I assumed it was supposed to have a wheel the way the tongue has the groove and slot for a wheel mount. Ours didn't have one when we bought it used, but I had an old one which I use when straightening the trailer on the patio. Leon is right - if it's not on the level it is very difficult to move and we only have a 2619!

[BobWilson]

As a mechanical engineer with some weld design and stress analysis experence I will throw in my thoughts on the subject.

The thickness of the rectangular tube is only 1/8 thick, based on measurement of the thickness of the similar rectangular tube used to support the slideout. The bracket for the pin looks to be at least 3/8 thick. As a rule you only need to make the weld bead as big as the thinnest member (1/8 inch) for full strength. The welder in this case made a very large weld which looks stronger, but likely weakened the structure by overheating the rectangular tube section when trying to apply enough heat for the thick bracket, and maybe even thinned out the wall of the rectangular tube in the process, a common occurance called burning.

The frame normally experiences compressive forces on the top of the tube and tensile stresses on the bottom of the tube with the center of the tube being neutral (neutral axis) when the trailer is not under acceleration or deceleration. Steel is weaker in tension than compression as most materials are. The farther from the neutral axis the greater the stress. So the bottom is going to have the highest stress which is apparent from the failure picture.

Since the modification puts the forces on the hinge pin area, at the corner, where the crack started is the most vulnerable. Instead of being distributed evenly, as in the standard trailer tongue, the forces are transfered over to the side of the hinge pin. The hinge pin necessarily is not perfectly ridgid in order to provide the swinge action. So the vibration of traveling down the road caused a fatigue of the metal on that corner and caused failure.

This is not the kind of failure you would expect from folding the trailer hitch backward to the parking position. These stresses would be very small compared to the stresses experienced when driving down a road with dips and bumps especially at typical driving speed. These irregular surfaces in the road will cause the load to shift significantly and rapidly up and down causing bending stresses as well as longitudinal jerks tensile stresses on the tow vehicle hitch. Those combined forces, vertical bouncing and horizontal pulling, fatigued the metal and lowered the tensile strength to failure.

It is an easy repair for a certified welder. First remove the electrical cable attached to the bottom of the rectangular tube. The paint and rust needs to be removed and a v-notch cut in the crack with a hand grinder. He would be advised to support the frame by placing a jack near the crack under the rectangular tube on the trailer side of the crack. This will tend to pull the crack together. Weld the crack all around to the other side. Also weld the crack that appears to be forming on the top bracket that shows corrosion.

A patch could be welded over the crack for added measure of security but not totally necessary. If using a 1/8 thich steel plate as a patch grind away the weld flush to make a flat surface.

Then grind flat on the bottom surface of the rectangular tube. It recommended to weld a 1/4 inch thick strip as wide as the rectangular tube on the bottom side of the rectangular tube at least a foot long. But a strip the full length of the rectangular tube to the trailer frame would be better. Welds would be made completely under the hinge bracket (with the pin) and cracked area. Then welded on a spacing of 2 inch long every 6 inches to the end of the strip. The strip should be welded on both sides of the strip along the rectangular tube. Another 1/4 strip on the top side of the rectangular tube would add even more strength, but not necessary. Be sure to clean, prime and repaint the bare metal surfaces.

Hopefully the Trailmanor Factory has some experience with this failure and would give a good repair recommendation also.

Good Luck,
Bob W.

[B_and_D]

One of my former clients (God rest his soul) was a mobile welder. He used to repair a lot of farm machinery in the Salinas Valley. Perhaps the factory would give you approval to hire someone to come to your home and do the welding? It's just a thought. I don't blame you for being reluctant to tow it with that big crack.

I got a little lazy. I should have posted the final resolution a couple of weeks ago.

I was waiting for the local welder to send a guy out to do the repair. There was a two week backlog. After a week and a half I called the welder to confirm. They reported that the one guy they send out for onsite projects had been injured and would be out for several weeks. So I cancelled. I had been very patient, but time was now running out. I have a trip planned for 4/5-4/9.

I called the TM factory, but it was late enough that they were already closed.

I call my local dealer, Stan, at Dinuba RV. He said he had a local welder that he uses for various projects that was more than qualified to do the job, but he was not portable.

Next morning I called the TM factory to tell them the story. They had no objections to my local dealer fixing it, but were very reluctant to cover transportation costs from my house to the dealer, about 130 miles.

I then called Stan at Dinuba RV. I told him the factory would authorize him to repair it but that they were very nervous about the cost of transporting it. I said that if I had a low boy trailer I could haul it myself, but I didn't even know where to rent one.

Stan said he had a transport trailer that he used for attending RV shows, and a few hours later he was at my house loading the TM.

Exactly one week later I picked it up and brought it home.

I can appreciate the factory's position. Under normal circumstances the owner is responsible for towing the TM to the dealer for warranty repairs. However, this particular failure required special handling.

Though I don't fault the factory, I do think they could have done a better job. Quite frankly, I'm a little surprised that the engineers that designed the frame appear to have no interest in attempting to determine what the cause of the failure was. I hope no one else ever has this problem.

I am very pleased with the response from my local dealer. He used his own time and equipment to come to my house to get the TM and arrange for the problem to be resolved. Kudos to Stan and Dinuba RV.

The repair actually included a modest improvement. The way that the factory constructs the swing away tongue, there is a little bit of slop because the curb side pin sits behind a steel plate and there was about 3/32 inch of slop in it. The welder that performed the repair of the crack modified the tongue to move the pin closer to the curb so that it went through a new set of holes in the swing arm and fixed frame. There is now no slop as I brake or accelerate.

[rickst29]

I guess this second failure (yours) made quite an impression with him! For my order (2619) he proposed to order it with the regular hitch from TN, and then have his local welder convert it into a more trustworthy swing hitch. I wonder how this new Dinuba version will compare with Bob's recommendations above?

PopB, can you post a few photos showing how the frame was repaired?

All --

Just wanted to share my experience last week.

I have a new '06 2720SL that we purchased late last summer. We stored it in our garage through the winter without the stabilizers down -- so the the weight was just on the tongue dolly wheel and the two tires all winter.

We decided to take the TM out for its first trip of the spring, so we were set to roll it out of the garage. I maybe moved it about 3 inches before -- BAM! -- the dolly wheel snapped right off and the entire weight fell onto the retractable jack bar (barely missing my foot).

Apparently, the dolly wheel is connected using one single bolt that is somehow pressed into making a "lip" that keeps it connected; there are no nuts or screws holding it together. I suppose storing it all winter with the weight on the wheel caused the thin "lip" portion to get very weak and break at the first movement.

Oddly, this was the first time my TM dealer had heard of the problem; they simply took another dolly wheel off another TM on the lot and replaced mine.

I had never read that you SHOULD put down all the stabilizers during long periods of storage, but now I'm convinced. Also, I will now only use the dolly wheel for times when I need to move the TM, and NEVER have the weight on that assembly for long periods of time.

Just a heads-up.

- Mark

Originally Posted by Larry_Loo

PopB, can you post a few photos showing how the frame was repaired?

I just got back from a trip tonight. TM is already in the garage. Had to close it down in rain and mud, so it will be out next weekend for cleaning. If I don't have a senior moment and forget, I'll take some pictures of the repair and improvement.

[rickst29]

My 2619 was set up for delivery this AM, but it had an unfortunate run-in with broken pieces of other people's left-behind tire chains over Donner Pass.

It's got the 'built-by-Stan's Welding Shop' Dinuba custom Swing Tongue. Seems relevant to this discussion, so I'll shoot and post a couple pictures after they fix up the breakage (elsewhere, not the hitch) and bring it back over the hill. (Probably a couple weeks; the forecasts for the next 8-10 days have enough precip that Cal-Trans won't get the freeway cleaned up enough to risk trying again.)