zero Posted March 7, 2013 Share Posted March 7, 2013 I'm wondering if anyone has found a way to stop roof sag on a pop-up roof Chinook. My 1978 was terribly sagging and I know I am not the only one. I've seen many with temporary wooden props inside when parked. I've stripped mine down bare and repaired several broken mounts with epoxy and fiberglass, I also added some 1" square aluminum supports. Still, it sags. The aluminum I added sideways does not flex. The problem is the little boxed section that runs along both sides where the metal supports attach to. It droops. Most of the sagging and flexing is happening on the sides 4" from the edges and not in the middle. There is no way to put any full span supports inside . I can't figure how this roof ever worked when new - but I assume it did - at least for a short period of time. Much of the OD of the roof along the side edges is cracked from flexing back and forth. I'm reglass it all over the place which I'm sure is making the top heavier. I'm kind of stumped over this. Maybe it's just bad design? Oddly, I have two Chevy Blazer Chinooks with similar pop-up roof camper bodies made by Chinook. They look near identical to the Chinook on my Toyota and are not sagging. If anybody has had one and found a good fix, I'd like to hear about it. I'm considering running some supports on top of the roof and glassing them in. I'm also thinking of adding some sort of permanent supports inside that help hold the roof stable when it's down and traveling. I'm well aware there is a dedicated forum for Chinooks at Yahoo. Oddly - I don't encounter a lot of people that know a lot about Chinooks over there. Quote Link to comment Share on other sites More sharing options...
MontanaChinook Posted March 7, 2013 Share Posted March 7, 2013 If you're going to find them anywhere, it's there. I think there just aren't a lot of people who know a lot about Chinooks, period. Personally I don't see any more extra-specialized knowledge of any Toyota motorhome style here than I do there. There are a few people who know quite a bit, and a lot of people who know a lot about bits and pieces but not necessarily the whole. Just like here. From the knowledge you seem to have, I'm surprised you're looking to either group for advice here. I would think if anyone can figure out a solution to something like this, it would be you. Quote Link to comment Share on other sites More sharing options...
zero Posted March 7, 2013 Author Share Posted March 7, 2013 If you're going to find them anywhere, it's there. I think there just aren't a lot of people who know a lot about Chinooks, period. Personally I don't see any more extra-specialized knowledge of any Toyota motorhome style here than I do there. There are a few people who know quite a bit, and a lot of people who know a lot about bits and pieces but not necessarily the whole. Just like here. From the knowledge you seem to have, I'm surprised you're looking to either group for advice here. I would think if anyone can figure out a solution to something like this, it would be you. I have to admit I get tired sometimes with some of these inane projects I get involved in. Repairing something that wore out is one thing. It's the "re-engineering" that tires me out. I often feel like I'm the long odd-ball with some of these esoteric problems. In the case of this Chinook - I was hoping someone else spent an inordinate amount of time fixing one and found a good work-around. I wanted a pop-up roof Chinook for many years. Very rare in the northeast. Now - I sometimes think I goofed. The Chinook is a poorly built RV when compared to many others I've worked on. My 86 Winnebago Phasar is built and designed MUCH better. So are the few Sunraders I've seen up close to. Even the late 70s Chinook RV bodies on my Chevy Blazers are built better. But they have the steel truck bed to support them, unlike a Toyota Chinook that has to be pretty-much self-supportive. I have a Jayco slide-on truck camper that is one of their cheapest versions with a pop-up roof. That being said I could walk on top and it barely flexes. On this Chinook - if a mosquito flew over and dropped his wallet on top of this Chinook - I'm not sure it could take the weight. I guess I'm just a little Chinook weary at the moment. Every aspect of it so far has been a challenge. Quote Link to comment Share on other sites More sharing options...
zero Posted March 7, 2013 Author Share Posted March 7, 2013 Here are some photos of jacking the roof. Also of customizing it in order to install a bigger 14" power vent and a crank-up Winegard TV antenna. I had to add some raised wood frames for level and rigid spot to mount either. All glassed in with epoxy. When I got the Chinook, the floor was so warped and cockeyed - I had to fix it first so I'd have a place to put jacks down - to jack up the roof. With the jacks, the roof straightens right out nicely. Take the jacks out, and it slumps right back down. Quote Link to comment Share on other sites More sharing options...
MontanaChinook Posted March 7, 2013 Share Posted March 7, 2013 Nice vent! It looks like on my Newport, the vent is 14". I don't know what to do about the fact that it's sealed shut right now...get it unstuck and re sealed, or just pull it out and put in a new one. I do think its important to have a way for hot air to escape UP. I guess I'm lucky since this is my first motorhome. I have nothing to compare it to, so I'm just going with it. My roof doesn't have sag. I agree. It's one thing to build/ engineer something. It's another to try to fix and make better what someone else already under- engineered. Quote Link to comment Share on other sites More sharing options...
WME Posted March 7, 2013 Share Posted March 7, 2013 From the pictures it looks like you are going have to connect the roof supports to some new supports on the side. Quote Link to comment Share on other sites More sharing options...
zero Posted March 7, 2013 Author Share Posted March 7, 2013 From the pictures it looks like you are going have to connect the roof supports to some new supports on the side. Yes, but I see no way to do it from the inside. The pop-up "shelf" is in the way. I'm wondering now how these things held up when new? Maybe relied on just the integrity of the fiberglass? Chinook DOES warn in the manual to never put any additional weight on the roof. It's one reason why I kind of hate adding braces. They add weight and might be defeating the intended purpose. Quote Link to comment Share on other sites More sharing options...
linda s Posted March 7, 2013 Share Posted March 7, 2013 Can you remove the braces you already put on and add some end plates the height of that lip on the edge? Linda S Quote Link to comment Share on other sites More sharing options...
zero Posted March 7, 2013 Author Share Posted March 7, 2013 Can you remove the braces you already put on and add some end plates the height of that lip on the edge? Linda S I don't think so. There's no place to attach anything under that boxed area. Just thin fiberglass. I don't fully understand how that boxed area is attached to the sides. I'll never know I guess unless I tear it all apart. I DO know the box is just fabricated from strips of plywood and glassed together. I kind of hate to tear it all out. It's about the only part of this Chinook I HAVEN"T ripped apart. The front had also been badly sagged in the middle but that was due to the small wooden supports being separate from the fiberglass. I reglassed that part and it's now fine. This thing has me a little baffled. I can't figure exactly what was responsible for weight bearing integrity. I'm thinking now that maybe nothing was. kind of like a bridge built out of toothpicks. Everything there must be perfect for it to work as a unit and one weak link ruins it. That's the way the floor was designed. I'm thinking I've got "fatigued" fiberglass with many small cracks in it. I just got done moving some snow and firewood - so I'm heading out to the shop now to burn up what's left of my brain on this thing. Considering the age, i can't complain as long at this thing did NOT sag for its first 10 -20 years. I don't know, one way or the other. I DO know, . I asked for it, and I got it. I cannot blame anyone else. This roof is the last big hurdle in this thing and the rest ought to be easy. I found over a dozen holes drilled into it that I had to glass over, so I figure someone's been climbing on it one time or another. Quote Link to comment Share on other sites More sharing options...
bajadulce Posted March 8, 2013 Share Posted March 8, 2013 I don't own a Chinook so don't have much to reference. The main pic w/ the jacks and what you've described seem to suggest that the roof's perimeter is acting like a hinge as it has lost its rigidity? Is that what you're describing? Not sure what's behind the fabric that is hanging down, but maybe you can run some ledger/support ran along the sides as Terry suggested or perhaps some intermittent triangles such as the typical shelf uses. Or maybe even a piece of aluminum angle iron ran down that side w/ a few triangle braces.. that prob overkill? Strange that those supports didn't span all the way to the perimeter of the popup top. The central portion of the popup looks like it has decent bracing and even a little positive bow to it as well. Dunno why they wouldn't continue that bracing all the way to the end. I can picture opening/closing the pop up by pushing on the central portion. No wonder that cantilevered outcropping along the perimeter turned into a hinge. Keep bending something back and forth and it loses all its integrity eventually. Quote Link to comment Share on other sites More sharing options...
zero Posted March 8, 2013 Author Share Posted March 8, 2013 I think I found an answer. Something I suspected earlier but wasn't sure until now. I think the Chinook relies on having two rear ceiling-height cabinets. They actually support the roof and keep it from sagging like mine did. My Chinook was missing those cabinets. In fact, many I've looked at for sale also had them missing. Seems to be a key part in the structural integrity of the roof. When torn out, and the Chinook gets driven, the roof flexs, cracks, slumps, etc. So now it seems I need to build some cabinets in back where I have some temporary support poles at the moment. It seems the Chinook IS like a bridge made out of toothpicks. I.e., everything needs to be intact and in good shape. If the floor sags, the roof will sag. if cabinents get ripped out, the roof sags, etc. I think I feel better now and I apologize to the Chinook creators for bad-mouthing their design. Seems what they did worked if kept intact and dry. I am wondering though - did they bribe somebody at the EPA to get that 29 MPG fuel mileage rating? I got this "insight" after reviewing some photos of another guy's rig and project. Quote Link to comment Share on other sites More sharing options...
WME Posted March 8, 2013 Share Posted March 8, 2013 Looking at the new pics, I think that the answer is in the triangular braces. Just make them larger and tie the sides to the "box" structure. Steve is headed in the right direction of thought with the old fiberglass on the roof acting as a "hinge", especially if is has mini cracks like you say Quote Link to comment Share on other sites More sharing options...
Dolphinite no longer here Posted March 8, 2013 Share Posted March 8, 2013 Jdemaris, Nice work so far. Its quite a long road you're on here, particularly the engineering one. A friend of mine in Ketchikan, Alaska has drawn the perfect T-shirt for you and other Chinook owners. It says: "Ain't no nookie like chinookie." Keep punchin', you'll get it done... John Quote Link to comment Share on other sites More sharing options...
bajadulce Posted March 13, 2013 Share Posted March 13, 2013 New pics bring new light and can see why this failed. Get the grinder out and start glassing. Quote Link to comment Share on other sites More sharing options...
Mikesta Posted March 13, 2013 Share Posted March 13, 2013 Yea, same here with the Camper shell... when I took the cabinets out, everything collapsed. Quote Link to comment Share on other sites More sharing options...
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