I've had crossovers in my doors for 4 years and the glue (some black stuff) that the original shop used to install came loose after 3 or so. I duct-taped them in place and they stayed for another year, but now they've fallen again and are blocking the window. I think it's heat-related...what do you all recommend using to keep them in place?

 

I used to be a professional audio installer. When the shop had it we used strip caulk. Yes like caulking for your bathroom. You should be able to get it at Home Depot or Lowes. Since heat is a major issue here in AZ we also used to just wrap the crossovers in carpet and/or zip tie it when convenient. Hope this helps.

 

i cut out an area in the styrafoam and mounted mine in there

 

I used a couple thin (1/2") strips of 3M auto trim molding tape down the length of the crossovers. If you clean the surface well (remove debris and wipe with alcohol) it lasts forever. Crossovers were still FIRMLY attached in the doors for over 6yrs. I did the same with 7/8" tape for my HID ballasts (1 under battery & 1 onto washer reservoir) and after 3ys they only came off with a LOT of the 3M adhesive remover and a gasket scraper.