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1978 Toyota Chinook floor rot


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This new floor is slow going but is almost done. I got the 1/2" poly-iso insulation in and just got the new final top-layer dropped in. The top is "A" grade rot-treated marine-grade 3/8" Douglas Fir plywood. The 1/2" thick frame work inbetween the top 3/8" and the bottom is 1/2" treaded CDX plywood is made of strips of 1/2" pressure-treated and dried plywood.

I also had to rebuild the perimeter of the doorway. It originally had a strip of 1/2" plyood all and this is what the exterior door frame got screwed to. I added new double (and glued) 1/2" dried treated CDX plywood and two 4" white cedar (rot resistant) side casings. Everything along the way has been coated with either epoxy or polyurethane. The coating/waterproofing takes a lot of extra time waiting for things to dry. When all done there will be no visable seams in the finished floor.

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  • 1 month later...

Awesome post. Am looking to do something similar to my '77. Debating tearing out the whole floor, and reinforcing as you did, or just repairing the section with rot (behind driver's seat, where fridge was). One question I had was how you supported the shell with the floor completely torn out?

Jed

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Awesome post. Am looking to do something similar to my '77. Debating tearing out the whole floor, and reinforcing as you did, or just repairing the section with rot (behind driver's seat, where fridge was). One question I had was how you supported the shell with the floor completely torn out?

Jed

Four bottle jacks. One under each corner of the Chinook body with a flat piece of wood between the jacks and the fiberglass. That held it up in air fine.

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looks like you're making progress! :)

Thnx a ton for sharing all this great info. :first:

Just an FYI to other readers:

The sunrader floor is almost identical to what you've shown w/ your Chinook in that the underlying supports don't extend to the perimeter of the shell. They fall way short. Meaning the Sunrader shell is also suspended in limbo by the floor around this perimeter. Toyoguy uploaded some pictures that show this in detail.

I'm not seeing how this new arrangement is holding up the shell?

I imagine epoxy and/or routine painting would be sufficient protection for the underside of this. My own painted/glassed plywood flatbed seems to be holding up decent enough to road wear (tho it is pretty easy to replace). Adding a thin layer of aluminum or something else in an attempt to shield the plywood might seem like a good idea, but could potentially trap water and only make matters worse in the long run. I think Toyoguy laminated a piece of FRP to the underside of his subfloor which seems like a good idea if the FRP and plywood are super bonded together. I believe he described a "super paste" concoction over the phone that prob did the trick.

Interesting that you've rebuilt this subfloor while the truck was still under the shell. Would you do this differently in hindsight? i.e. remove the shell completely?

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Just an FYI to other readers:

The sunrader floor is almost identical to what you've shown w/ your Chinook in that the underlying supports don't extend to the perimeter of the shell.

I'm not seeing how this new arrangement is holding up the shell?

If you are referring to what I did . . . I added aluminum cross-supports that go the entire width of the RV body. The steel vertical 1" square supports in that RV body bolt to the the new aluminum cross-pieces. It has full width support now - so I'm not sure what it is you are not seeing.

I imagine epoxy and/or routine painting would be sufficient protection for the underside of this. . Adding a thin layer of aluminum or something else in an attempt to shield the plywood might seem like a good idea, but could potentially trap water and only make matters worse in the long run.

It originally had an aluminum skin with staples and small holes all over the place that lets lots of road-water in. Now with the thick epoxy skin it is water-sealed.

Interesting that you've rebuilt this subfloor while the truck was still under the shell. Would you do this differently in hindsight? i.e. remove the shell completely?

No, but I wish I could of jacked it up higher. I could only go as high as my 8 foot ceiling. Another foot would of been very helpful. I don't see any advantage to take the body completely off unless it was to put it upside down. The worst part of this job is using epoxy and fiberglass to bond the new floor to the old RV body while upside down.

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sorry for the confusion.

I meant that the sunrader's subfloor support system is very similar to your original Chinook support system. What you've done to extend these supports is very much what sunrader's could benefit from as well.

@ not seeing how the shell is held up:

I see how the floor is supported, but was wondering how this translates to the shell and how the 2 were joined.

Where the floor was butted up against the shell, did you use any glues or nut/bolts/screws to your framing? Does your framing have an outside "tack" edge, flanges, or perhaps a ledger that the shell can be fastened to? Is it held in place by the fiberglass around the interior? This is what was curious about.

@ epoxy/glassing underside.

Upside down would have been nice for sure. Tho just titling heavily to one side would have been just as helpful. There are some pics of a Chinook shell upside down in a shop somewhere (guy put on a Tacoma I believe).

nice comfortable looking shop btw! :)

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  • 6 months later...

jdemaris -- Thanks so much for all this detailed info! I'll be sure to reinforce my floor like this too. But first I need to do a similar project that involves lifting the camper shell off the truck frame, and there are a couple issues I'm hoping you can shed some light on for me.

I'm thinking of swapping camper shells -- more specifically, replacing a heavily damaged hard top Chinook Omega shell (currently attached to a good running truck) with a pop top MPG/Gazelle shell (currently attached to a rusty, non-operable truck). Both trucks are the original late 70s Toyota Hiluxes. Also, I'm operating under the assumption that the rear truck frames are the same for these two different model Chinooks, and just the camper shells and rear bumpers are different.

If the rear truck frames are the same, then my plan is to lift the shells up with bottle jacks like you did, but high enough so that I can just drive/push each truck out from under each shell. Then, if this works, I'd just back the good truck under the good shell and lower that shell into place.

So I'm wondering...

1.) If you hadn't gutted your interior first, would any of the propane, electrical or water storage systems have gotten in the way? I know I'll have to disconnected wiring from the cab to the camper. I know I should disconnect and remove the propane tank. And If the appliances and furnishings stay in the camper shells when I lift them, then I know I may need to reinforce the floors a little when I lift, especially if the floors are rotted. But am I missing anything?

2.) I'm also worried about the fill pipe for the gas tank. How do I detach it from the fiberglass? Is the pipe rigid? How can I most easily work around it while swapping shells?

Any tips you or anybody else who's done a build / swap like this could give me would be hugely appreciated. Thanks!

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