31-34' aft of the axles frame inspections

[HeavyAssault]

Anyone have any comments about the long term stress on the rear frame section? Looking at several different AS with the long rear frame section aft of the axles. This area looks like an area I need to part particular attention to while inspecting as well as down the road.

Just hoping to hear what people have seen, repaired, or whatever.

[perryg114]

Usually, frame damage is caused by rear end separation from poor maintenance which leads to water intrusion and degradation of the connections between the frame and the shell. The shell supports the frame. The biggest culprit is the plate at the back that funnels water under the rear of the trailer which rots the floor and frame back there. Rear bath trailers are the ones you want to stay away from in long trailers. In the late 70's they started putting center baths in trailers and had less issues with rear end separation. These center bath trailers are also easier to repair at the rear. In the late 70's they started using a box beam for the rear frame rails where before that it was a single channel. In the early 80's they went to OSB floors that tend to rot fast.

Perry

[HeavyAssault]

Is this commonly found on 2000-newer trailers? Poor maintenance meaning monitoring rivets?

[tjoneillMO]

The shell supporting the frame seems counter-intuitive since all loads are ultimately transferred through the trailer frame and the shell even when removed requires the support of some type of frame. When removing the shell from the trailer on my 23' 1976 Safari I noted that there was little or no frame under the rear corners of the shell. There is a .090 thick steel angle plate bolted to the frame rear channel to which the aluminum shell is is riveted, this area was separated but there was also corrosion due to the dissimilar metals in contact without galvanic isolation.

I'm planning to weld a steel support frame extension around the back corners so I can bolt the shell to some frame feature in this area as it's not that difficult to do. The frame z-channel at the rear in this vintage seems to be pretty cheesy though, still thinking about how to rework this area given the plumbing and wasetwater tanks.

[perryg114]

The more connections between the frame and shell the better. I have suggested a perimeter frame with bolts every few inches. The shell and frame need to be one. The shell is very strong since it has a lot of moment of inertia.

Perry

[tjoneillMO]

I agree--just bolting the shell channels to the outriggers looks pretty weak too. It's not that big a deal to weld a 1/4 x 2.5 bar into the top of the outriggers and have complete perimeter support.

Tim

[cwf]

my 1999 34' had an issue with the 'frame' on the street side, aft of the axles. It was determined that the AS had been left 'nose down' on a mountain in New Mexico where snow drifts spent a lot of time in contact with the AS. The rust removed, the frame strengthened and rear separation avoided.

Timely checkups... key.

[perryg114]

I was thinking more of a piece of angle iron or channel.

Perry

Originally Posted by tjoneillMO

I agree--just bolting the shell channels to the outriggers looks pretty weak too. It's not that big a deal to weld a 1/4 x 2.5 bar into the top of the outriggers and have complete perimeter support.

Tim

[JimGolden]

They deepened the frames in 1985 and a lot of the issues went away.

Not totally sure, but would imagine a 31' has a greater rear overhang than a 34'.

I'm not a big believer in the shell holding up the frame theory. I think there are too many cutouts for it to really be monocoque. But, most of the ill stories I heard were in the pre-1886 years.

I would think a 2000 or newer would be fine. Make sure to balance your running gear and haul your black smith tools in the front, and you should be OK

[perryg114]

There are cutouts Jim but most of them like the windows have frames around them that take up the load. If there were holes without frames then you have a weak spot there. The door opening is the biggest weak spot. Even the OEM vents on the older trailers have aluminum frames around them. Cutting those out to put in a fantastic fan is not wise.

Perry

[tjoneillMO]

Steel angle would be easy enough to install as perimeter support, where curved it would need to be formed or you could cut plate and attach a flat bar to make a formed angle. The outriggers on my '78 are formed out of .110 thick steel and look to provide a decent amount of support but more is probably better here.
Tim