The big right hand cab window in the excavator has mostly come unglued. I have fixed it before with urethane sealant. I just can't get a good bond on that plastic! Not sure if those are acrylic or polycarb, but guessing polycarb as it's notorious for this. That window is very difficult to deal with being next to the boom.
Need to use the exact same stuff the body shop uses to glue a windshield in. Everything has to be CLEAN, wiped down with adhesive remover or similar before applying new, window included. Since it was glued once, the window itself might be a pain to get the urethane to stick to. I had a window cut from Plexi for the windshield on the 210 a couple years ago when the wait for new glass was weeks, glued it in same as the glass and it hasn't moved.
Polycarbonate is more scratch resistant than acrylic, so it's most often used as a replacement for glass. 3M will have a product for adhering to it, but you must ID the type of plastic before you make an adhesive selection. https://www.3m.com.au/3M/en_AU/bonding-and-assembly-au/applications/material-bonding/engineered-plastics/ Both Bostik and JBWeld also manufacture some excellent plastic adhesives. But you need an adhesive/sealant that remains flexible after curing.
3M™ Auto Glass Urethane Windshield Adhesive 8693 10.5 fl oz Cartridge And the secret sauce for a good bond on plastic or old urethane is to coat it with 3M™ Single Step Primer 8682.
Yep need to use a primer first.
Sikaflex I wrote a bit on it here Polycarbonate windows use different "adhesives" than glass to secure. I don't come here a lot, BUT, I thought I'd share. I have Lexan (polycarbonate) windows coming loose (OEM) on my Caterpillar excavators, and my replacement Polycarbonate windows continually come unbonded on all my machines. As it turns out, you CANNOT use the same adhesive and primer as one... HeavyEquipmentForums
Double sided tape might be an option depending on how wide the bonding surface is https://www.homedepot.com/p/Scotch-...ided-Extreme-Mounting-Tape-414DC-SF/203405976
Always use 3M primer 94 if you really want it to stick for good.
Polycarbonate expands at a rate higher than glass. Using 3M windshield urethane or its equivalent will result in bond failure. Sikaflex 255FC and the associated primer are the ONLY way to attach/ reattach Polycarbonate windows. IIRC, cat had a service magazine or letter on that big window (boom side) coming loose, followed shortly thereafter with instructions. That big window came loose on our 324D and 330C machines, all because Caterpillar used conventional glass mounting urethane. They've since changed that. The thread that I linked above talks briefly of the expenses we incurred when using the wrong adhesive. On the first of those that I did, I lowered one boom cylinder out of the way. On all the others, I just worked around them.
Thanks a ton! Yep, indeed I already knew polycarb was a real PITA to get adhesion to and it has a high rate of thermal expansion. That boom side window will very much suck to remove entirely so I don't want to do it twice. Still have not decided if I will really remove it entirely.
The attached appears to be the latest version of mother Cat's instructions for replacement of polycarbonate (& other) RH cab windows on excavators. I know the title states it is for Next Gen excavators but I think the recommendations it contains should work for any age of machine.
couldn't you use a gasket like glass windows are set in?
Nope. Not an option. Just use the sikaflex and primer and be done with it. Never had to do one twice.
Ha, ironically I was just calling around to try to find it. No one in the city has a clue.....typical. Our glass company told me "nothing will stick to it, don't even try"...... Someone should have told CAT that. how much effort did you use to remove old material? Usually on glass, we can either get it to cut nice with a sharp knife, or have a blade we put in a sawzall. I just don't think we need to really get down to bare steel as that is not the disbonding point. I want to say Sikaflex name is familiar. May also make RV sealants.
I got it from Jamestown Distributors. The damned primer is the expensive part. Being not glass, and already partially loose, a knife works just fine. I skinned mine down to thin, and primed both the window and the opening. Since it started as a failure, it is important to remove as much as possible. The other issue was finding a caulking gun sturdy enough to push it.
That's the easy part.
Same DeWalt that I use, except mine is covered in black goop. Thanks for sharing Heymcall. I forgot about your previous post regarding the subject. Like you say, the primer is expensive and considered hazmat. It’s difficult for me to ship it. Thats why I use the NAPA 3M stuff. Most of the NAPA stores stock it for me, so I can pick it up when I get off da plane. I would sure like to find someone willing to perform remote glass work. Nobody wants to do it.
I’m curious as to why it isn’t an option. Couldn't the material of choice be installed from inside the cab instead of the standard way, from the outside ?
Did you take the whole rh window out or did you just repair the adhesive that was loose? Also I'm guessing you can get the spacer blocks from cat? The black paint is what let go on my windows.
The whole window. Just need two guys to reset it as my suction cup just slides around on polycarbonate. The instructions above tell how to treat the fretting (edges).
I wonder if Lord fusor would work ? They claim it holds just about anything (made nearby here) However the plant just blew up this morning.....
The front windshield in my 953C started coming loose around the bottom about 10 years ago. Used regular ol' silicone from Wally World and it's still holding today.
I'll try those products. As anything else I have tried just breaks loose in a few months. Did you use the cleaner an primer on the frame? I would think just the glass would work since that's the part having the problem adhering?
My 2ZN 953C had a floating windshield, ie, held in by the outer bolted on trim.
this is what happens to a 953c windows when 7 jack a×××× Steal it and roll if off their trailer on the way taking it to the person they sold it to. It needs more than silicone. The bad part is I personally talked with people. 10 known machines stolen by these same people an nothing happens to them.
BBX series
Damn that sucks! BTW - Welcome to the Forums.