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If you trust self-taping screws to work out in the middle of the floor why wouldn't you trust them to work in the areas where you can not use a bolt with a nut on the bottom?
My thinking is that the screws outside the wall-channel are primarily holding the floor down while the bolts inside the wall-channel are primarily holding down the shell. The shell is a lot heavier and hence more likely to exert greater forces than the floor. Yes?
__________________
Todd
“Twenty years from now, you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines, sail away from the safe harbor, catch the trade winds in your sails, explore, dream, discover, and change habits.”
- Mark Twain
Last edited by monocoque : 05-01-2008 at 09:05 PM.
Here's a photo of the large bolts and larger square steel washers securing the wall-channel above the front and rear cross-members. In the second photo are a number of the rusted elevator bolts I removed from various places in the wall channel but mostly through the outriggers. The screws in the floor outside the channel through out the trailer were in good shape.
__________________
Todd
“Twenty years from now, you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines, sail away from the safe harbor, catch the trade winds in your sails, explore, dream, discover, and change habits.”
My thinking is that the screws outside the wall-channel are primarily holding the floor down while the bolts inside the wall-channel are primarily holding down the shell. The shell is a lot heavier and hence more likely to exert greater forces than the floor. Yes?
The issue is not as much the magnitude of the load as it is the varied and repetitive loads cause my moving the trailer down the road. If you imagine traveling around a curve at 60+ mph... the wheels and frame want to hold the road, but the shell wants to be flung off into the pasture. This will be happening repeatedly and in varied direction based on which way you are turning. Just like breaking off a bent nail... you bend it back and forth until it snaps off.
I think your plan is a sound one and would not jump through any hoops to make changes at this point. Just use high quality fasteners to insure that they will be up to the task.
My thinking is that the screws outside the wall-channel are primarily holding the floor down while the bolts inside the wall-channel are primarily holding down the shell. The shell is a lot heavier and hence more likely to exert greater forces than the floor. Yes?
I am not sure it will be the same with your heavier frame but it seems to me that on the original frames the shell actually holds up the frame not the other way around thus the problem with the frame seperation.
Gees, I don’t know how I missed this thread before. You’re doing some first class work, Todd. You’re going to a have a much better frame than the factory model.
A couple of observations. I used the same bolts Malcolm shows back in post 169 for the cross-members. That’s what the factory used originally and all were in good shape when I removed the old floor, so I figured they must be a good choice. Around the c-channel perimeter in the outriggers, I used elevator bolts similar to the factory originals, as well (1/4” x 3”, IIRC). We secured these with hardened washers and double lock nuts on top of the bolt. Those large bolts with the rectangular flange pictured in post 196 were replaced with stainless and new flanges. Added a couple of extra to help fight the rear separation issues. Also used lots of sheet metal screws all around the c-channel. When all was in place, I went back and sealed the c-channel fasteners with Sikaflex 221, hopefully to keep some of the water out of the belly pan, in case of the inevitable leak. One thing I wished we’d done differently: use only stainless fasteners everywhere we could.
A couple of questions. I have to admit, I skimmed thru parts of the thread, so forgive me if you already answered these. Are you going to POR-15 the new frame? It’ll be a lot easier on a new frame with no shell to work around. Are you planning on closing up the ends of the box steel to keep moisture out? Seems like that would be easier that trying paint/POR the inside of the box.
Keep up the good work. I’ll be reading along as you go from here on out. Really interesting thread. BTW, I nominate this one for a sticky thread, anybody else agree?
Jim
__________________ Any significantly advanced technology is indistinguishable from magic. Arthur C. Clarke, C.B.E. (1918-2008)
I am not sure it will be the same with your heavier frame but it seems to me that on the original frames the shell actually holds up the frame not the other way around thus the problem with the frame seperation.
After the frame was pull out it was interesting to observe the side-to-side flex in the main rails behind the axles. I didn't notice much up-and-down flex although the original material is definitely quite thin. However, this trailer must have been sitting up quite a bit in the later years rather than traveling and thus I found no rear-end separation.
__________________
Todd
“Twenty years from now, you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines, sail away from the safe harbor, catch the trade winds in your sails, explore, dream, discover, and change habits.”
After the frame was pull out it was interesting to observe the side-to-side flex in the main rails behind the axles. I didn't notice much up-and-down flex although the original material is definitely quite thin. However, this trailer must have been sitting up quite a bit in the later years rather than traveling and thus I found no rear-end separation.
Rear end separation also doesn't happen when the running gear is properly balanced.
Since you have the trailer taken apart, you should do the rear end modification, so that you don't have trouble later.
Andy,
he's building a brand new frame with slightly stronger stock, so I don't think he needs to worry. : )
Marc
Then even more so, since the frame does not hold up the shell, but because the shell holds up the frame, additional holdowns at the rear now become mandantory, since the stroger frame is also heavier.
It's a simple thing to do when everything is open.
Please do! I'm sure the welder would be thrilled to have another task tacked onto the job. Post 'em here if you like. I'm sure there are others who are interested as well.
Here are a couple of pictures of the spare tire carrier. the vertical angles mount on the cross member where the "A" frame terminates. The tire sits in the well created by the "A" frame. The forward part extends past the closure cross member at the forward end of the coach and attaches to a bracket there that I know I have but can't find right now
Am I remembering correctly that there are pivot points at the bottom of the vertical angle brackets in your photo? I still have my tire bracket but have not looked at it in a while.
Then even more so, since the frame does not hold up the shell, but because the shell holds up the frame, additional holdowns at the rear now become mandantory, since the stroger frame is also heavier.
It's a simple thing to do when everything is open.
Andy
Hi Andy,
It sounds like a very logical thing to do, and as always your input is incredibly valuable and much appreciated.
I'm wondering how you would advise to effect this change-- do you use more bolts through the c-channel at the rear, or more bolts/screws into the frame away from the c-channel, or some combination of the above, or something else that I have completely missed?
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