My Explorer's back window keeps breaking when towing

[bonniemeikle]

Hi, all. This is such an informative forum, I haven't really needed to post before.

I have an annoying issue with my '91 Explorer 4x4. The old gal has been through a lot, had many parts replaced but is still performing fairly reliably for us.

We have gravel roads around us since we live in the country. So, when I was towing our utility trailer (4x8) it wasn't entirely surprising that I lost the back window to what was probably kickback of gravel. Ok so we put the mudflaps back on.

Lost another window to the same thing. Yes, trailer has fenders. A couple of years go by and things are fine. After window #3 bit the dust we put one of those fringelike skirts at the back of the truck. Yesterday it happened again!!!!

I find it hard to believe that it is still rocks doing it, when I was going not so fast on the gravel and I have the flaps and fringe there. I guess anything's possible.

Has anyone else out there had a similar dilemma? At least I'm pretty familiar with my local auto wrecker by now but it's getting costly.

cheers...

 

[gijoecam]

My best guess is that the tongue load from the trailer is putting some funny loads on the frame which, if not fully intact thanks to rust, could be transferring some of those loads to the body and tailgate, twisting it and popping the glass. I wouldn't suspect kick-back unless they were some REAL large rocks and they were flying extremely fast and high.

Maybe try leaving the window ajar on the bumpy parts? Or, remove the window, place some masking tape or string in an X tightly across the empty opening, then connect the trailer and see if any of the strings changes length... that could indicate some twisting or creaking (it's rudimentary, I know)...

Sorry... I have no clue on this one.