Trouble with a Compression Boot between the Topper and Cab

[ADDvanced]

I recently picked up a new (used) topper for my 94 Dak. It does not have a front window on the topper, instead it has what I discovered is called a compression seal that pushes up against the rear of the cab.

Type 540 is what I have

The biggest issue at the moment is the compression seal/compression boot between the topper and the cab; the lower radius does NOT match the shape of the window. When I installed the topper, I used ratchet straps through the front windows to pull the topper forward tightly, but it isn't enough.

Water will run down the outside edges, then wrap inwards and come in the bed where the seal joins together in the middle. It actually pools up a bit in the center of the seal, when you're inside the truck.

I sketched a quick diagram of the situation and attached it.

Options as I see it:

1: Remove topper, apply giant bead of silicone, reinstall and hope for the best
2: Remove topper, remove seal from topper, grind out lower corners to more closely match radius of rear window, spend $75 on new, slightly longer seal, reinstall
3: Attach trailer full of gasoline leaf blowers connected to bed with hoses to maintain positive pressure inside bed like Roadkill's backyard supercharging episode

Any ideas? Again, new to trucks, I had no idea that toppers without forward facing glass were even a thing. I like the concept of it though; I can keep the AC on, open the rear window, and now my doggo isn't in an oven.

 

[ADDvanced]

 

[Buliwyf]

I'd just put a window in, or wall it in.

 

[ADDvanced]

No.

 

[Kingsize24]

Remove both windows completely, then install this... https://www.accordionboot.com/?gcli...AbvCQa8tYerrGhe3Ev65xE2_lICZ2uUUaAmisEALw_wcB

Alternitavley. I've seen a few guys also add this to just the sliding rear windows if you have them.

 

[javajoe79]

I have some of that accordion boot that I'm not using if you're interested in going that route. They also sell the inflatable donuts that you put in the the void to seal it up.

 

[ADDvanced]

Yeah I'm not interested in removing both windows. Will definitely want to be able to close it off during winter.

I read this on the FAQ:

"
I have a Ford F150 with a LEER top. I an pretty sure the accordion seal is the correct option but the warning that the opening must be an exact match has me concerned. It looks like the truck opening is larger at the lower corners but until the window is removed, who knows? Am I on safe ground getting the accordion seal for this application?

The accordion boot only stretches one direction. There is a metal clip embedded in the rubber that allow you to attach the boot to the fiberglass/sheet metal, Therefore both window openings must be the same size. If the opening in the shell is smaller you can cut and trim the fiberglass to match the truck's window opening.

"

So I think I'm going to remove the cap, and try to trim the fiberglass. I'm also going to loosen the bolts on the bed, and try shifting the bed rearwards about 1/2". This should help it seal a bit better, so the front isn't just smashed right up against the cab so tightly.

 

[rayra]

seems like you need to find a seal that is larger than your shell opening. Temporarily stretching it into alignment will work for a short while, but as soon as you have enough frame flex / travel movement, it will seek its own shape and get misaligned again.

And just a notice on such shields, you're going to want some clear film protection on the back of your vehicle's cap, because eventually enough dust and micro-grit will be between the boot and the cab and will act like sandpaper. Doesn't matter whether you have a rubber flange boot, an inflated one, rigid foam, whatever.

 

[ADDvanced]

Well, I think I fixed it. I pulled the topper, pulled out the seal, and used a jigsaw to make the lower corners a tighter radius. I made them go a bit lower and more outwards than the rest of the shape, to get the seal around the rear window frame. I reinstalled the compression boot, but now I had another problem: There wasn't enough of it!

A new seal would be ~$70-100ish, and cmon, this is a budget build! After hunting around at hardware stores, I wound up with a $10 roll of 'flex tape', it's a butyl rubber tape with some crazy adhesive on it. I threw one strip on the bottom of the gap, then filled it with strips of tape.

I then wrapped one long piece across basically the entire bottom, but I forgot to photograph it. It came out awesome! It flexed just like the original seal, super pissed I forgot to photograph it! Anyway, reinstalled the cap on the bed, again with ratchet straps pulling it forwards. Added a bit of silicone on one pesky gap, so it should seal pretty well now.

 

[ADDvanced]

Also, not worried about the paint at all, the seal actually sits on the frame of the rear window, doesn't touch the paint at all.

 

[rayra]

You'll see. Been there, done that.
But it looks good anyway and nice solution with the butyl rubber flashing. I used it as a sound / road noise absorber in my Suburban floor and rear wheel tubs. Really takes the high frequency noise out.

 

[ADDvanced]

I'll see what? It's not touching the paint. It rests on the rubber protrusion/rear window edge. Pissed I didn't take a photo of how that 'fix' turned out, was pretty stoked about it so I got to excited and installed it before shooting it.

 

[Martinjmpr]

You'll see. Been there, done that.
But it looks good anyway and nice solution with the butyl rubber flashing. I used it as a sound / road noise absorber in my Suburban floor and rear wheel tubs. Really takes the high frequency noise out.

Rayra: It's not like it's a brand new $50k truck. It's a 94 2wd Dakota that he picked for $1800. If I had a rig like that, keeping the paint "pristine" would be pretty low on my priorities list.

I'll see what? It's not touching the paint. It rests on the rubber protrusion/rear window edge. Pissed I didn't take a photo of how that 'fix' turned out, was pretty stoked about it so I got to excited and installed it before shooting it.

Sounds like you have a workable solution, I wouldn't worry about anything else. As we used to say in the Army "If it's stupid but it works, it isn't stupid."