What's a good product to fill a large gap? Butyl? Caulk? Currently there is some sore of white putty there. Background: 60s Jag. These cars came from the factory with a 1/4-1/2" gap between the splash panel and inner fender (brilliant!). Some cars have a rubber flap strip screwed on here, but some don't. I'm probably going to try to do both. A factory reproduction isn't available, or even mentioned in old part catalogs. I'm guessing this gap is there to allow for body flex as it's a unibody, but these cars are notorious for rusting out because water and road gunk makes it past this gap. Here's mine. Inner fender on the right. here's one with the rubber strip.
Sounds like a fight you can't win! Have something attached to inside of fender and it will 'ghost' on the outside, especially if it's in contact or overlaps with the inner shield. Have something attached to the shield and it's going to rub against the inside and not seal as well. The best would be an accordion of a lightweight, weatherproof material that is solidly attached (but easily removable ).
Hmmm... good points. No one seems (no pun intended) to know what exactly was done at the factory, but whatever they did was wrong anyway. So, I need some sort of thick, water and element-proof, non-shrinking adhesive sealant for large gaps. Any suggestions? I could layer up butyl caulking strips, but that stuff doesn't keep its shape, so once compressed, it stays compressed. Anyone try heavy-bodied seam sealer? It sounds like it might work... but it's $50, so I'd rather not just take a chance on it, or waste half the bottle. There are a lot of SEM and 3M adhesive sealants and they all basically sound the same.
I was thinking something more like accordion door material, glued to each side with a fold across the center of the gap. These are expensive, but give you a starting point. https://www.lowes.com/pl/interior-doors/accordion-doors/vinyl/2215969099-4294965742
just my 2 pennies but butyl will stay flexible enough to allow a small bit of movement between the 2 panels. ive used it to seal a camper roof and windows with good luck.
The old Dodge trucks used to use fender welting, the modern version is a 3/4" wide flat rubber with a round dead on the outer edge. The flat side fit between the fender and the bed sides, the round bead filled the gaps. The fender welt is sold by the foot, and isn't very expensive. With what you have, I'd probably just use the butyl.
I might try a universal trunk seal. The kind that slips over the edge of the pinch weld on the trunk opening. Something like this. 5M Black Rubber Seal Protector Weather Strip Lock Trunk Hood Edge Car Door Trim | eBay
I was thinking about something like that pinch weld seal. It looks like there are some that might work. Fender welting might be a good solution, too, if I can find a way to stay stuck to the fender with all the conditions behind the wheel