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Post by atefooterz on Jul 21, 2015 23:27:14 GMT 10
Hiya just a general question about alloy frames, as no one needs to rip them open to repair rot i have not seen what was used.. I am curious about the corner & lower skin frame- floor interface beam specs. My van has damage on the fridge area bar and at least one rear corner. I was wondering about replacing these with alloy so no further issues will occur regardless of water etc. I can access bending sections to the radius or cut & gussett weld but am interested in what the factory)ies) did.
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Post by doublechevron on Jul 22, 2015 13:07:01 GMT 10
I can't find the thread, but one of the caravans in teh last few months in "hall of fame" is an aluminium framed 'van lifted off to expose/repair the chassis. You should be able to see there. They are just pop riveted together.
seeya
Shane L.
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Post by atefooterz on Jul 22, 2015 13:20:53 GMT 10
Cheers Shane, it is the size and thickness i am after. No need to do a dodgey with pop riveting as this will be sections of stuff that will last way beyond the caravan they are fitted to. And as a bonus any size Franklin that era can fit because they are designed to bolt onto the existing timbers above the average rot height. Also not only being a common shape plus rot resistence but much lighter than the made to budget and used of the shelf extrusions of that time tech. Thinner wall larger size = stiff and strong where as back in even the early 80s it was still as much about thick walls = strong and because it is alloy it will be light enough compared with timber thing.
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Post by doublechevron on Jul 22, 2015 13:35:55 GMT 10
One rivet is a good way of doing it. It'll allow the frame to "move" as the caravan moves along the road. If it's solidly welded or riveted in a number of places to solidly lock the rhs tubing together .... it'll fatigue crack rather than flex/move  .......... At least that's my theory on why they have lasted so long! That rotten old caravan dismantled in the thread I mention has what appears to be a brand new frame in it. If it was wooden framed there would have been nothing left! seeya, Shane L. |
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Post by atefooterz on Jul 22, 2015 13:45:44 GMT 10
One rivet is a good way of doing it. It'll allow the frame to "move" as the caravan moves along the road. If it's solidly welded or riveted in a number of places to solidly lock the rhs tubing together .... it'll fatigue crack rather than flex/move .......... At least that's my theory on why they have lasted so long! That rotten old caravan dismantled in the thread I mention has what appears to be a brand new frame in it. If it was wooden framed there would have been nothing left! seeya, Shane L. The natural flex is why i am favouring just one piece rolled than gusset welded, as that will be very stiff. These frame sections will be big enough to share the flex & point load into the alloy timber interface at each join point. (elongate the timber holes over time- if flex loads are that high), i may even put bushes in there so that naturally will happen rather than compromise the strut sections. Rivets would also allow a designed fail/ antifail point but starting from scratch that seems a bad choice for the long term. |
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Post by Deleted on Aug 4, 2016 5:29:18 GMT 10
Something to note with ally frames is the rivet gauge , ours has popped a few on its initial trip home from Broken Hill  and I had considered re drilling the holes and re fixing with a larger gauge rivet but after talking to an engineer mate he said to use what was there originally as that was the best stress fail point a popped rivet is an easy fix  a twist in a frame or fold in a ally sheet is not so easy  , so I now look at the rivets in a different light they not only serve to hold it together they are a pressure relief point  |
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Post by atefooterz on Aug 8, 2016 3:28:52 GMT 10
Something to note with ally frames is the rivet gauge , ours has popped a few on its initial trip home from Broken Hill and I had considered re drilling the holes and re fixing with a larger gauge rivet but after talking to an engineer mate he said to use what was there originally as that was the best stress fail point a popped rivet is an easy fix a twist in a frame or fold in a ally sheet is not so easy , so I now look at the rivets in a different light they not only serve to hold it together they are a pressure relief point Where abouts have they popped? all in the same area or random? This may be a warning about something on the chassis come unwelded and causing excessive flex. A mate with another sort of trailer had popped ally pop rivets, against what i said he went for not only bigger but stainless pops, tore his nice panel. Underneath two welds on the chassis crossmembers were cracked so the topsides were wobbling on bumpy roads. |
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Post by Deleted on Aug 8, 2016 7:58:31 GMT 10
Only 4 I have found so far and they are random my guess is 48 years of sitting in one place then a 9hr quickish trip from Sydney home and the flex popped them , a couple were popped prior I would suggest looking closely at the condition of the paine around the hole . Good tip re the chassis check however that is on the list when I can get it on the hoist to do the undersides :-)
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Post by dandt on Aug 9, 2016 9:33:26 GMT 10
My '76 Millard has 25 x 25 x 1.6mm channel and 25 x 28 x 1.6mm channel horizontal. i.e. the vertical studs fit inside the horizontal studs. 1 rivet in each joint.
They had usually just cut the side and bent the flat where it was a fold and just bent it for bends.
Denis
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.......... At least that's my theory on why they have lasted so long! That rotten old caravan dismantled in the thread I mention has what appears to be a brand new frame in it. If it was wooden framed there would have been nothing left!
and I had considered re drilling the holes and re fixing with a larger gauge rivet but after talking to an engineer mate he said to use what was there originally as that was the best stress fail point a popped rivet is an easy fix 
a twist in a frame or fold in a ally sheet is not so easy 
, so I now look at the rivets in a different light they not only serve to hold it together they are a pressure relief point 
