An unusual frame

[57BB]

After a successful liftoff of the shell of my 1953 Liner, see thread under 54 Liner...can't seem to get a 53 category opened , we discovered an unusual frame.

The frame rails are 4" C channel with a welded plate forming a box beam at the double axle. The cross ties are 2"x1.5" angle. The outriggers are a custom shape C with a 2" top and 1" bottom flange...the web is 3" tall.

Surprisingly the cross members are covered with a U shaped channel of alclad that is 4" deep.

Primarily the belly pan is attached to these alclad channels and then perhaps one or two rivets into the bottom flange of the outrigger.

For a 29' long trailer there is almost nothing supporting it and frankly I can now see why these monsters just didn't survive.



So I'm curious what others think of this. Has anyone else come across such a light frame on such a large trailer? Any successful re-engineered frames out there? I'm hesitating in adding much, the trailer, though beaten was not in completely terrible condition, certainly the frame has survived in pretty decent shape.

I'm considering beefing up the outriggers, replacing them with a heavier version and perhaps welding a angle under the outrigger to provide additional stiffening. I'm also thinking to add an addition cross member at the rear and then perhaps an additional lower angle at every second member.

I'm very curious what others think...


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[r carl]

Now you can build a proper frame.

[perryg114]

How did it look before you took it apart? Airstreams don't suffer weak frames so much as they suffer from weak attachments to the very rigid shell. You can spend a lot of money on a supper rigid frame that will support itself without the shell or you can do a better job than Airstream did of attaching the shell to the frame.

Perry

[57BB]

Perry, it looked great actually. The trailer had sat on a horse farm since the mid 60s...used as a house trailer and apparently as a horse trailer. A really poor floor replacement was done in the forward section...no plywood under the c channel and glued to the frame. The rest of trailer was basically original.

You are completely right, the original factory connections, very few elevator bolts and minimal protection to the edge of the plywood are the two things I could see that aided in the deterioration of the frame to shell connect.

I agree and I think my gut instinct is likely correct. Don't fix what ain't broke...but do fix what is. I know a rigid frame is not necessary, nor is a deeper cross section of steel. I'm strongly leaning towards strengthening and minimal additions.


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[perryg114]

Well remember also that most of the Airstream structural problems occurred with stuff got heavy and they started adding holding tanks that stressed the frame. The more modern trailers usually have some sort of mid bathroom with the tanks close to the axles. If you are going to bring it up to modern specs you will have to do something to make things stronger. If you are going to try to make is all original, then you probably don't need to change much. Adding more out riggers and connecting the ends of them so you can attach the shell to the frame every few inches would help. Areas to support large holding tanks will need to be beefed up. These old trailers were pretty light.

Perry

[Wabbiteer]

Ponder a frame as a large axle mounting bracket with flex sprung & snubbed using plywood as stiffening braces & the plywood floor-loaded weight as reaction mass to reduce the frequency of heave oscillations . If we add one new area of rigidity the motion the factory allowed will be amplified or focused somewhere else. So, increasing the quantity of stock outriggers would have the advantage versus doubling outrigger thickness if done uniformly around the perimeter, maybe see it as a trampoline effect that is a sound design as long as neglect and/or too many cosmetic-only damage repairs have not elapsed in its previous history.

While you are rehabbing the existing iron maybe don't get too aggressive - you don't want to be removing too much good metal surrounding the rust pits trying to get all of it, or say using too fast an aggregate if sand blasting that chews away good metal along with the bad like I did on my hitch A-frame with coal slag glass. There was not that much metal to begin with, a sound reason something like POR-15 (paint-over-rust-15) exists...

Whoever you choose to do welding will have quite the challenge on some of the thin mild iron for sure

[57BB]

Originally Posted by Wabbiteer

Ponder a frame as a large axle mounting bracket with flex sprung & snubbed using plywood as stiffening braces & the plywood floor-loaded weight as reaction mass to reduce the frequency of heave oscillations . If we add one new area of rigidity the motion the factory allowed will be amplified or focused somewhere else. So, increasing the quantity of stock outriggers would have the advantage versus doubling outrigger thickness if done uniformly around the perimeter, maybe see it as a trampoline effect that is a sound design as long as neglect and/or too many cosmetic-only damage repairs have not elapsed in its previous history.

While you are rehabbing the existing iron maybe don't get too aggressive - you don't want to be removing too much good metal surrounding the rust pits trying to get all of it, or say using too fast an aggregate if sand blasting that chews away good metal along with the bad like I did on my hitch A-frame with coal slag glass. There was not that much metal to begin with, a sound reason something like POR-15 (paint-over-rust-15) exists...

Whoever you choose to do welding will have quite the challenge on some of the thin mild iron for sure

Thank you so much for more or less confirming what my instincts were/are telling me.

This frame is very finely balanced and though flexible quite well thought out and aside from 5-6 failing outriggers in great condition. When I towed the trailer it was remarkably unremarkable...a testimony to that original design.

Frank Yensan quite rightly reminded me that this is the third year of the ladder frame and was the largest trailer they made. Certainly they were thinking about weight and keeping this beast safely on the road at the same time.

At the end of the day I'm having new outriggers fabricated and will replace only that bad ones...I'm not adding any they are not needed.

I'm going to add additional cross members at the bottom of the frame rail to help keep it from flexing outward or inward...a design defect I think needs to be addressed. I'll add material equally on each side of the axles.

Though I'm planning on grey and black tanks with this trailer I won't be traveling with the tanks full. I plan to add moderate reinforcement for the tanks.



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[57BB]

Frame has been restored and reinforced. We replaced about half of the outriggers. At most we added 25 pounds to the weight of the frame.



Next painting, two sprayed coats of POR 15. Then onto attaching the new aluminum channels used to support the belly pan.



Then onto the new plywood floor. All bolted down and ready to go. Oh yes exposed bumper and hitch have a top coat of shiny black.



New solid axle, leaf springs and aluminum wheel wells are next.


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