Tab 400 screen door string repair

Vlemussmith

Thank you for the reply Scott. I did find a pdf from @vhollow that was excellent help and he suggested 60# .70mm monofilament leader line so I ordered it. Just as he noted, I could see that a couple of the screen eyelets were worn where the cord ran thru and a bit and rough so this was a concern. We'll see how it goes. 

vhollow

I repaired my door twice. The replacement cord quickly frayed and broke. The monofilament has lasted me 3 years and 30,000 miles of trailer travel, and is still going strong.

vhollow

I also recommend, as Scott did, that you shrink wrap the crimps.

Vlemussmith

Thanks @vhollow! Your pdf was really well done and appreciated. I can clearly see breaks in 2 of the eyelets that really need to be filed down or something.  What do you suggest to smooth them somewhat? 

vhollow

I didn’t mess with those grommets. They do look fragile. Perhaps you could bend any sharp edges with small needle nose pliers, or use a very small round file. I don’t know if a small chainsaw file might fit.

Vlemussmith

@vhollow. Yep. Started filing sharp edges a bit. Thank you 

ScottG

Interesting. I didn't notice any breakage on the screen pack eyelets, though I admit I didn't look that closely.

I'm only a few trips in with the fishing line, but it just seems superior overall. Very smooth, very strong, and doesn't stretch/bunch like the polyester cord seemed to do. 

Vlemussmith

I’m glad to hear it because I also discovered the little plastic piece I removed from the top of the pull rail has quite a deep gouge in it from the cord that passes through it that I’ll need to smooth it out somehow. 

ScottG

I noted that groove in my repair as well, but I don't recall mine being quite that deep.

That sort of wear is what prompted @vhollow to replace those friction points with small rollers while he had his door apart. I didn't do that, but may consider it when/if I ever have to tackle this again.

Vlemussmith

So far so good… we’ll see how this does. 

Vlemussmith

UPDATE: I can't delete my comment but I see this is a style of crimp so NVM. 

@ScottG or @vhollow - I’m now questioning whether these are actually crimps or some other part in the kit. They have a flanged end - 2 sizes) and smaller will actually fit into larger. What do you think these are for?  NuCamp sent 8 total.    

vhollow

Beats me! I didn’t come across anything like that. Perhaps you could use the smallest one that will fit (I crimped them with a jeweler’s crimper, then folded them on themselves lengthwise to be more compact and tube shaped-trying not to forget to put the shrink tube on the long lines first). Maybe you could file off the flange first?

ScottG

The little flanges are weird--I wonder what the point is. It seems like that could just be another edge to promote chafing.

I also wonder why they provided two sizes. I would use the smallest one that works for the number of lines it needs to contain.

Vlemussmith

I agree. I am going to buy some regular crimps instead. Further inspection only one of them was smaller the rest were all the same size so I don’t think they were intended to slide together… Thank you both for replying. 😀

SteveAA

Many thanks to vhollow, ScottG, and MandoBiker for tips. Just did the victory dance after repairing my broken screen door cord, 2018 T@B 400.

My problem was the plastic piece at the bottom of the pull bar, see ScottG's January 2022 post above. Rather than having a slight groove worn into the plastic, mine was worn all the way through. This is a flaw in the design, IJMO. I repaired it by shaping a small piece of metal to wrap around it. We'll see if it lasts...

To replace the drilled out rivet on the bottom right that the cord wraps around, I used an 8/32 bolt with a  nylon lock nut and a nylon spacer filed to fit.

Vlemussmith

Yea!! I just finished my '17 320s screen door too! I removed both rivets on bottom left (inside looking out) and only the bottom right rivet leaving that side rivet intact. There are 2 rivets ea. side.  Since I used fishing line it was easy to simply manually thread line around the bottom flange/roller guide.  I needed to file deep gouge the top plastic flange where line comes out of the pull rail wider and smoother so that worked. I also added the shrink wrap around the crimps.
Taking it apart was easy but I was really intimidated to remove the original string but once I did it really wasn't hard to figure out.. of course the input and help from vhollow, ScottG and MondoBiker's notes I would never have succeeded. Thanks so much!! .  I will say, my hands (not a youngster)  were really sore by the end of the day as working with 60# line was a bit tricky. Thanks again. 

KK1L

I have yet to have to restring, but am anticipating it. Along the line of using fishing line (of course the pun is intended) I was thinking of braided. There are color options as well...bright yellow so you don't walk through the screen (!), grey, cammo, etc. Anyway I am more considering possibly the improved functionality (more slick than mono). Any experience with this out there?

Jay1415

I just completed the screen door repair in our 400 and I made some small mistakes. 

1. I skimmed through this material and ordered the 1 mm nylon cord recommended by Madobiker. Had I read all the info, I may have opted for the fishing line or maybe a 1.2 or 1.5 mm braided nylon. The original cord is certainly not up for the task and it strikes me as planned obsolescence. I'm confident the 1 mm cord is better. Hopefully good enough for a long run.

2. I didn't understand Scott G's excellent diagram of the door, so I made a small modification that didn't matter. (I pretty much followed vhollow's directions and forgot about Scott's writeup.) In the top of the door, the cord runs from an anchor (the tensioner), around a plastic fin, and to the pull bar, which is where the cords slide. I modified the "top flange/roller" in Scott's diagram with a smooth metal replacement, but the cord doesn't slide there. I think the main cord damage occurs at the top and bottom of the pull bar. 

3. When I installed the mesh pack, I did it backwards. Meaning I put all the strings in the door frame (no space to slide) and the taped side in the pull bar (which has a triangle shaped channel for the cords). I also forgot to loop some cord around the "flange/roller" so nothing worked. Since I had cut the cord after installing the tensioners, I had to restring the door. I got the door apart, restrung and into the camper in an evening. (I knew what I was doing the second time.)

Recommendations. 

1. First thing, I'd use some masking tape and label the left side, right side, top, and bottom pieces (inside). I'd also label the inside bottom of the pull bar. It's best to have a 6 foot (minimum) bench with access to all 4 sides, but I had access to only 3 sides, so I had to spin the door around and flop is over a number of times. You have to take apart all 4 sides and the pull bar, so it gets confusing how parts are oriented. I also added pencil lines on the top corner joints because assembly is not super obvious. 

2. If the cords are broken, the door is dead. Be brave and continue. None of the instructions will make sense until you dig into the problem. I was too tentative trying to figure out how to repair the door without drilling the pop-rivets and how to figure out how the door was strung before cutting cords. The bottom pop-rivets need to be drilled and there's no way around that. (Drill slowly, just the head, and punch out the shaft.) The lacing diagram by Horrex is excellent an easy to follow, so don't try to figure out how the existing cord is laced. (I taped the strings to the bench as I proceeded just to keep things organized.) Also, make sure the bottom three cords and the top three cords don't intertwine. 

3. I replaced the pop-rivets with screws and nuts, but to hold the nut with a fine needle nose, I needed to cut some plastic to gain access. (Dremel and a razor knife.) This was the back side (street side) of the door, so the cuts are not seen once the door is in the camper. I used some bicycle cable ferrules as spacers (to get the nut above the bottom channel) and ground the ferrule end, but cutting up a pen would also work as a spacer if you're not a cyclist. One of these spacers is also a "bottom flange/roller" in Scott's diagram, but remember that the cord doesn't slide at this point. So to repeat, as you drill out one pop-rivet, the shaft of the pop-rivet acts as the "bottom flange." So the cord loops around the pop-rivet and you need to replace that flange somehow. 

4. I think it's a good idea to use some shrink wrap around the cord crimps that slide in the pull bar. My shrink wrap was too large (and would require too much heat to shrink it), so I carefully filed the corners of the crimp. My guess would be 8 mm shrink wrap would be the ticket, but you only need a few inches. 

I took some pictures but they're worthless (and mainly show the corners as a document for reassembly).

Good luck, 

Jay

ChrisK

Testing a prototype on my daughter's 400 screen door.







I designed these 3D printed parts to replace that pesky rivet pivot point. It also allows the frame to be screwed back together. It can be used on both sides. The hole is for the cord to go through. It has a radius on the pivot point. It's just hard to see with the black plastic. The bottom part that the screw goes through has a "shaft" on it that is the size of the hole in the frame and corner piece and goes through both so it locks the location in place. The screw will (when I get longer ones today) go all the way through the frame bar. Testing will tell how it does. Waiting on the crimping pliers to complete the job. Should be here today.

Jay1415

https://i.postimg.cc/63D5z66L/IMG-0853.jpg

Here's the pull bar. I think the main wear occurs at the top and bottom. 

If your part is "bottom flange/roller" that Scott refers to in his diagram, I believe (but could be wrong) that the cord does not move at that point. It simply need to "loop" the cord so the door can open all the way. Without it, the door could only open to the tensioner location. 

Correct me if I'm wrong. 

ChrisK

You are correct. It is just there to create a path for the string to wrap around. It is not a rotation point. I believe you are correct about the break point. That, I believe, is where my daughter’s screen string broke. 

ScottG

Agreed. I used "flange/roller" in my schematics for lack of a better term, but there is no major movement of the string at that point. There might be a bit of chafing as the string is stretched and relaxed during use, but it probably minimal compared to where the strings enter and exit the pull bar, as well as inside the pull bar where the individual strings move past each other and through the screen pack grommets. 

The latter is where both of my breaks occurred, which prompted me to make the second repair with monofilament, and to cover the crimps with heat-shrink tubing to blunt any sharp edges. 

ChrisK

Finished the restring. It really wasn't that difficult once you figured out how it works. I used both guides and just kind of winged it. The factory guide was great for routing. You really don't need a needle for routing the fishing line through the accordion folds. I simply tied the folds tightly together and fed the line through. As long as they are lined up, it will go straight through. I didn't really worry about lengths other than to make sure I had enough on the ends. I just made it look like the factory guide did, The 3D printed parts for the bottom of the door worked well after a couple revisions. The bottom is now screwed together instead of that big rivet. No drilling things out of this needs to be redone. I also recreated the upper corners somewhat to replace the ones that Tom's Camperland lost when they had her door for months. I've shortened them up a bit so they aren't as bulky. Need to take a trip to the hardware store for some matching paint. She is picking up her 400 from storage this weekend. We will install the door and adjust the tension. Then it is on to figuring out why her window screen keeps coming unstrung.

These are the 2 lower 3D printed parts. I didn't worry as much about looks as these will never be seen. The part on the left is the one that comes up from underneath. A screw passes through it and up in to the internal part on the right. You can see the hole for the cord to go through. 


The replacement upper corners. Need paint.