Front shell warp

[Larryjb]

My front shell bows out on the drivers side when it is lowering. I have to physically push it inwards to latch it. Is this simply an adjustment of the lift arm height?

[nwhouston]

Mine has always done this, particularly the driver side where all the cabling comes down the one support arm. When we latch up we both know to put a knee into the wall to push in so the bolts in the vertical support do not hold the top section from fulling seating. I just treat it as part of the process. However, if you read my new post on misalignment, I may just be living with a symptom of a larger issue that does not bother me.

Larry

[Larryjb]

I do see it as a potential larger issue. If this side bows out everytime the trailer is set up or closed, that is placing a big strain on the window frame which could cause window leaks in the future. Also, there is some "flapping" of the side walls of the upper shell. While it is good to have some flexibility, I am concerned that the additional strain of the bowing may ultimately cause a weakening of the roof to wall joint. This is probably not as much of a concern as the main flexing is along the lower edge. A third concern is how much strain it puts on the clamp holding the shell to the box when closed.

I did lengthen the rear lift arm by about 1/4". The effect of this would be to cause the lift arms to "stretch" out the bow. It does seem to have reduced the bow a bit. Interestingly, the entire shell seems to be pulled back by 1/8" now. I may try to shorten the front lift arm by 1/4" and see if it realigns the shell when closed.

[Larryjb]

I took another look at my TM and the warp. I noticed that the front lift arm is not parallel with the box. In the vertical position, both front lift arms lean outwards a few degrees. When lowering, the lift arms point outwards slightly, bowing the shell outwards. I am now suspecting that the torsion bars are slightly bent. These two torsion bars are also at their maximum adjustment, and not providing enough lift either. Perhaps when I go to Disneyland next, I'll drop into the dealer in CA and see if they can replace the front torsion springs for me, or at least sell them to me so I don't have to pay shipping from the factory.

[Bill]

Perhaps when I go to Disneyland next, I'll drop into the dealer in CA ...

Larry -

I'm sure you are aware that TM uses at least a dozen different torsion bars. Before you "drop in", it would probably be wise to arrange things with them by phone, to be sure that they have what you need when you arrive.

Bill

[Larryjb]

That's a good point Bill. It may be better for me to order the torsion bars from TM directly.

Anyone else noticing the front lift arms not sitting square to the box?

[Bill]

Larry -

I didn't mean "don't go to the dealer". I simply meant "contact the dealer well in advance and order the new bars". As you pointed out, shipping will be a bear if you have to pay UPS or whoever. If you get your order in early, TM has always been willing to put your order on the next truck to the dealer, for free. But with the currently-low production rate, the next truck might be two months away. Get your order in early, in other words.

I can imagine (barely) a situation in which a torsion bar might be bent. I'm having trouble imagining a situation in which two bars would both be bent, in the same direction (outward) by the same amount (a few degrees). If you order two replacement bars, what will you do if the new ones have the same bend?

Is there some other way to deal with this? I know you have thought about it a lot, and I haven't, but I'm wondering if there might be something you can do with the white lift arms, rather than the torsion bars themselves. Either modify the way they attach to the shell walls at their upper ends, or bend them slightly (dangerous, I suppose), or change the angle at which they attach to the stubs of the torsion bars at their lower end. By the way, the opening at the lower end of the lift arm was fabricated with a built in bulge, which surrounded the stub of the torsion bar. The four bolts surrounded the bulge. Several years ago, one of our members decided that this bulge was a flaw, somehow introduced by over-stressing something. To rectify the situation, he pounded the bulge flat. I think this would be a disaster, and might cause the kind of misalignment thing you are seeing. Are your arms properly bulged?

Keep us up to date.

Bill

[Larryjb]

As far as I can tell, the lift arms are appropriately "bulged". I assume this is to ensure they are crimped around the end of the torsion bar.

I'll try to take some pictures of the issue next week. It is raining now, and I've got the TM tarped for now. However, I can try to describe my observations.

I measured the distance between the lift arm and the box when the shell was lowered, but not latched. The lift arms for the front shell, but near the centre of the TM (rear-most lift arms for the front shell) are parallel with the box. The distance between the lift arm and the box is within 1/4 or less at all points along the length of the arm. The front lift arm is not parallel with the box. I forget the actual measurement, but it increases by almost an inch from the base where the torsion bar sits inside the arm to the pocket stop. This measurement was taken with the shell closed. This way, there are no outside forces as far as I can tell pushing the lift arm outwards.

I then checked the lift arms when the shell was raised. This is more difficult because the top of the box flexes quite a bit, so measuring the distance between the lift arm and box is not reliable. However, I can measure the vertical deflection from 0°. Again, I made fairly crude measurements, but these were done quickly to support my casual observation that the front lift arms were bending outwards. The lift arms at the centre of the TM (rearmost arms for the front shell) were nearly vertical. In fact, deflection from vertical was probably due to the fact that I don't have my TM perfectly leveled. The front lift arm is noticeably tipped outwards, and only held in because of the locking pin. In fact, the lift arm appears to actually pull the box out a little. Keep in mind, this is a slide model so that the box near the front does not any significant support keeping it vertical.

I am suspecting that after 17 years of use, the weight of the front shell has stressed the lift arm so that it is now bowed outwards. In the non-slide models, the box would have kept this straight.

You suggest that the issue may be with the lift arm rather than the torsion bar. I can put a straight edge along the lift arm to check. I didn't notice any bending at this point, but I'll check anyway.

[Bill]

Good description, Larry. We will continue to ponder it.

I am suspecting that after 17 years of use, the weight of the front shell has stressed the lift arm so that it is now bowed outwards. In the non-slide models, the box would have kept this straight.

If the lift arm is bowed outward, can you un-bow it in any way? If not, new lift arms are a lot cheaper to buy and ship than new torsion bars. And I think that unlike torsion bars, they are the same for all models, so you would be guaranteed to get the right parts.

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Terminology check. When I say "lift arm", I am referring to the white rectangular arm that is attached to the torsion bar at the lower end, and the shell at the upper end near the pocket stop. Each shell has four lift arms, two on each side. I believe this is your usage as well.

When I say "box", I am referring to the five-sided box that forms the body of the trailer - floor and four walls sitting directly on the frame. I am not referring to the pull-out box that is up front on a slide model.

Bill

[commodor47]

Larry,

Have you checked the lift arm pocket stop? If the white rectangular arm is straight perhaps the pivot point of the pocket stop is worn? If so that could cause the shell warp you describe.

It could also happen if white rectangular arm is too long relative to the arm on the other side of the TM. Open the TM and measure from the center of the outside pocket stop pin straight down to either the top or bottom of the curve in the torsion bar. It might be easier to measure from the top or bottom of the curve in the torsion bar to the center of the outside pivot pin. All the white rectangular bars should be the same distance on the outer shell.

Dick