Wheel well adhesive/sealer

[Aktundra]

Doing a shell off floor replacement of a 1963 Bambi

I have the replacement plywood cut and the next step will be to drill the holes for the elevator bolts. Once all the drilling is complete, I will coat the plywood with either marine grade enamel or marine grade epoxy.

some of the bolts will pass through the plywood and the new galvanized sheet metal wheel well covers. Before the floor is permanently bolted back in, I want to use an adhesive/ sealer to attach and seal between the wheel well covers and the frame.

What adhesive/sealer do those that have been down this path reccomend ?

[barts]

It is hard to beat polyurethane sealants - the usual Airstream ones will work fine - in this application. That said, this is likely not a very demanding area over time since with any luck there won't be a lot of sun shining there. Polyurethane sealant/adhesives are readily available from building supply places; you're not color constrained.

The thing to watch is any design that can result in water accumulating against the plywood or frame. If unavoidable, those areas should be heavily protected.

- Bart

[Aktundra]

When I removed the old galvanized wheel well covers they were in fine shape after 50 years, except the portion that is sandwiched between the floor plywood and the frame. The areas under the plywood were rusted and rotten, due to electrolysis of dissimilar metals or moisture trapped between the floor and frame.

The frame is now coated in POR15, the plywood will be coated, I just need a waterproof adhesive/sealer to keep wheel spray from working back in-between the sandwiched layers.

[Wabbiteer]

The plastic inner/outer liners on my '73 were bedded at the sandwich area with a 1/8" X 1-1/4" asphalt tape - butyl tape would be a modern equivalent, but vibration, heave-n-shrink, rust and dry-rot had defeated 60-70% of the tapes bond to the metal.... Which maybe points to the need to allow for some movement and not try and lock it down too tightly.

To get any caulk or sealant to bond to the POR-15 remember to degloss it with 400 grit paper.

3m 5200 marine adhesive sealant is the best there is for many applications but it is a hard setting & dense almost 'self-leveling' sealant that people bet their lives on in deep water yachts, it may tolerate the rack & skew & other flexing from road hazards well, but bond too well and let everything shatter if there is a blowout, etc..

How about spray auto body undercoating to bed them in while you assemble it - then a smoothed-on vulkem strip over the joint that extends low enough past the seam that it also acts as a drip-edge to guide dripping water past it even if the bond has cracked?