Signs of a rear section 'come-a-part' from bad axles ?

[Danny Bell]

Can those in the know please tell me the "tell tail" signs of rear separation of an AS due to running on bad axels ? Our AS is a 1966 Ambassador, if that era means anything out of the ordinary with the above scenario ?

Thankyou,
Dan

[Cochese]

Don't have any pics ,but rear end separation is often caused by rotted rear subfloor. There are many threads concerning this! If the axles are original, more than likely they need to be replaced...hope this helps

[dbj216]

Hi there! You have a 66 Ambassador and I have a 66 Trade Wind. They both have the infamous Corning curved glass windows with the phillips operators. These windows are unique and leak prone.

My 66 had rear subfloor rot under the silly console "window seat" hidden toilet. There could be floor rot under the tub drain line. And there could be floor rot due to a leaky rear window. The plywood subfloors in our trailers do not have a 50 year life span when exposed to moisture.

Rear end separation is when the rear of the aluminum body becomes "separated" from the subfloor and frame due to subfloor rot and frame rust. Our and all Airstreams are "semi monocoque" construction. Think airplane fuselage. The Airstream frame is built light and rather flimsy, the plywood subfloor is 5/8" and flimsy as you know from buying 4x8 sheets of it at the store, and the aluminum body is rather flimsy all by itself.

But bolt them all together and they become quite strong and light. So when the rear cross member rusts away, and the subfloor rots away, the body is no longer connected to the frame. Sooo, the frame flexes and can even bend or buckle from the axles back.

You can test for this by bouncing on the rear bumper of your trailer. Bounce, bounce and watch if a gap opens between the body and the frame rails that the bumper is welded to. If so, you have the problem and can start planning the repair.

My bet is your 66 will be okay. I might suggest if it were a 76 it would more likely have rear end separation. The 70s trailers have the new body style and a poor rear seal between body and subfloor. Water just pours into this area.

But you are likely to have subfloor rot which ought to be repaired. I replaced my bathroom subfloor, but the rest of my subfloor was okay, and my frame was in good condition.

Like cochese, I hope this helps...

David

[Danny Bell]

Cochese and David,

Thanks so much ! Very informative !

From my understanding of your replies, would it be somewhat accurate to say that separation is the cause of, 1) water leaks causing floor rot in the rear of the trailer ? 2) At which time rear separation is accentuated by worn out axles causing severe shock, at which time the stress on the rotted areas "give way" ?

We are the 4th owner of our AS. In the late 90's, the P.O. of the day totally went through the interior. Wood floors, new toilet, new shower/tub, wtr.htr., plumbing,electrical and so on. I realize there could still be unaware issues. In the P.O.'s design, inconspicuous inspection openings that enable one to inspect tub/shower, lavatory and water htr. are in place. After (2) years I've seen no evidence of moisture in these areas by vision. I have not yet used a moisture detection device. I have done nothing or know anything about inspecting windows for leaks. My concern has been the axles...oops ! I did notice the sub flooring that is flush with the rear of the trailer where the 12v electrical panel is, showed a little rot on the edge of the plywood. The plywood was "soft" for about a 1/4" when stuck with a knife, but then is solid. I applied a layer of silicone over the edge of the plywood all the way across. Was this a bad move ? Should I have scraped out the "soft" wood and then applied a sealer? With only a 1/4" of "soft" wood in this area do I need to perform a major repair ?

Axles...I don't know if a P.O. replaced them. The axle tubes have surface rust but the rubber donuts (for lack of proper terminology) look almost new. The tests derived from this form seem to be in spec. I will jump on the bumper tomorrow and come back with results.

Sorry for the lengthy state of the union address, I'm a worrier/perfectionist by nature ! It's our first AS !

Again, thanks guys !
Dan

[dbj216]

Worn out axles have hardened rubber rods, hard like a hockey puck. The Dura Torq axle design uses 4 rubber rods in the axle tube. A square steel member is inserted in the middle of the rubber rods. Your "swing arms" are welded to the square steel member. When your trailer hits a bump, the swing arm moves up, and the square member compresses the rubber rods. When they loose their elasticity due to age, then there is less "suspension spring" effect giving a rougher ride.

A rough ride can tend to shake things apart in and on the trailer. The cabinets may start coming apart, and riveted joints may start coming loose. If the trailer has rotted subfloor or rust weakened frame members, a rough ride will put additional stress on those members. Bad axles don't cause rear end separation, but bad axles can make it worse.

The small area of subfloor rot you found doesn't sound significant enough to worry about. Sealing it is a good idea as you may prevent further moisture intrusion into the wood grains. There are many products that soak into the wood and help protect it. Silicone may be more topical and not soak in well. I put polyurethane on my subfloor thinking it would soak in a bit.

I've got to get a moisture detector and check my trailer after a rain. It would help find where a leak is ending up, and thus trigger an investigation to find the leak source. Our mid 60s Corning windows are suspect.

David

[Danny Bell]

Is there a health issue related to using pressure treated plywood for sub flooring ? I have not yet read on this forum where it was used.

Danny

[dbj216]

There are lots of different grades of plywood for different applications. I do not know my woods very well at all; same with steels, and same with aluminum. These materials are sciences in themselves.

I used exterior grade 5/8" plywood for my bathroom subfloor job. I've used pressure treated lumber for other projects. This plywood was not pressure treated. I do not know what properties it has that makes is "exterior grade". I do know "marine grade" plywood is not necessarily waterproof.

I am not the least bit concerned about the health effects of 4x6 sheet of exterior plywood in my trailer. I'm much more concerned about the health effects of pulling my trailer down the highway.

David

[Lumatic]

Originally Posted by Danny Bell

Is there a health issue related to using pressure treated plywood for sub flooring ? I have not yet read on this forum where it was used.

Danny

I have heard pressure treated ply is subject to warping. There is a synthetic 4x8 sheet which others have used and liked but I don't remember it's name.

[Jim Foster]

If you have an outside storage area between the rear bumper and the rear wall, reach in and see if the bolts which hold the body to the frame are tight and in good shape.
When I had rear floor rot on our '65 Caravel those bolts were rusted and could be easily wiggled by hand from inside that rear storage area.


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[GeocamperAS]

For health reasons, Pressure treated in not recommend for inside living space. Especially inside small spaces like a camper. Also it is commonly 3ply which will warp. The more ply's the less warping. Look at it this way, mine took over 30 years before rotting in the bath or by windows. Buy at least a 5 ply and paint it with a primer/sealer before installing and you will get at least 30 more years out of it.

[Danny Bell]

Originally Posted by Jim Foster

If you have an outside storage area between the rear bumper and the rear wall, reach in and see if the bolts which hold the body to the frame are tight and in good shape.
When I had rear floor rot on our '65 Caravel those bolts were rusted and could be easily wiggled by hand from inside that rear storage area.


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Jim,

I have no rot that I have detected in the rear but, the bolt are a little loose. Thanks for the heads up !

Dan