Wheel wells over or under floor - Quick question

[Daytonacoupe]

Hello; the outside edges of the ABS black wheel wells on my 1987 Limited had been slipped under the OSB floor. They are in sad shape, and the floor had rotted and swelled where moisture had wicked into the OSB....not to mention that the floor would have had a slight impediment to a flush fit on the frame in this area.

I'm replacing the floor and considering having wheel wells fabbed out of aluminum or galvanized metal. Some nice work displayed on this site. Is there a downside to affixing the edge/lip of the wheel well to the top of the subfloor material vs between the subfloor and frame?

I'm thinking not but it's one of those things once done that is another big piece of work to undo.

Any thoughts; pro or con?....are much appreciated.

Cheers.

[Belegedhel]

I suspect the motivation to put the wheel wells between the frame and the subfloor was to "protect" the end-grain of the subfloor from the constant splashing in the wheel well. Other than that, I can't think of any benefit. If you installed them above the subfloor and either used some kind of super-subfloor material that never rots, or thoroughly protected the edge with some kind of penetrating epoxy, etc., then I suppose an advantage to having them above the floor is that if you had change them out, you could without quite so much surgery.

good luck!

[57Vintage]

I would recommend having a metal wheel well on the outside, below the subfloor, to help resist damage/moisture while traveling. A second inner wheel well that has a space between the outer/inner will allow you to add a little insulation inbetween. Every little bit helps.

On our 58 the inner and outer were both galvanized sheetmetal. There was some small cracks to the outer so I resurfaced with another layer of 20 guage galvanized and sprayed on a couple coats of automotive sealer to keep it weather tight.

[Daytonacoupe]

The feedback echoes what I had been thinking over. Pros and cons for each approach. Attach to the upper side of the floor and future repairs, hopefully not required, would be much simpler. But, the road water ingress would be more likely than if the lip is sandwiched between the frame and floor.

I like the idea of galvanized custom made wells, but where they attach to the outside aluminum wall in a high moisture environment, the aluminum could suffer. For those who go this route the caulking must be heavy. Perhaps galvanized with an aluminum lip where it attaches to the wall? Then the metal/aluminum union would be well inside the trailer.

[57Vintage]

I sprayed undercoat on the inner wheel well before mounting, inside and the outside lip that contacts the skin. After everything was mounted and the wheel opening trim installed I sprayed the inside area again to seal out moisture. around the joint.

That's more than the factory did and the skin and wheel well were still good after 50+ years.

I was curious about galvanic action between galvanized and aluminum and did some research. This chart helped me understand that these 2 materials are relatively compatible as long as the zinc coating lasts.

[Trons4u]

We have 2 wheel wells on our 1959 Tradewind, an inner and an outer with insulation between them.

The outer sits on the frame and attached to the frame/outriggers and wheel well skin.
The inner attaches to the subfloor and interior skin.

I also used truck bed spray liner to coat and seal the underneath, and that flex seal rubber spray around the subfloor and wheel well. That way, it's sealed from the top and bottom

[Daytonacoupe]

57Vintage; tucking it between the floor and frame does sound like it'll afford better protection to that corner of the floor. I do like the idea of metal. Or, maybe a more permanent vertical 2 inch high metal plate that could be welded to the frame, and would follow the contour of floor with the floor butting up against the edge. The sides of the well could be riveted or bolted directly to the plate. Somebody on this forum had shared photos of this approach. So many possibilities....

Great chart on metal compatibilities!

Trons4U; another vote for under the floor. Lots of sealant between metals and around joints. What came out had suffered badly from water.

Thanks so much for sharing your approaches. Very helpful as I narrow down the options.

Cheers

[Daytonacoupe]

A decision has been made; we'll weld a vertical lip to edge of the outriggers and axle holding plate that is the perimeter of the wheel well. The floor will but up against this lip. Then I can decide whether to adapt the plastic critters or fab galvanized units that'll slip inside the lip and be affixed to it. The frame will be finished this week and a photo will follow.

[Daytonacoupe]

Two photos of the wheel well ridges. Not the greatest shots but if you look carefully you'll see the simplicity. The old plastic wheel wells slide in nicely from underneath, and could be used if I cut off the horizontal lip that used to slide under the floor and above the frame. I hope to go with aluminum or galvanized, and now I can get the floor on and shell installed without dealing with the wells first. The new floor will butt up against these vertical ridges, and the wells will be fastened to them with stainless bolts. Now if a wheel well needs replacement it won't require wrestling with the sections that had been under the floor. Extensive frame repair has been completed (one main rail, 5 cross members and all but one outrigger). Hope to finish up the POR15 today. The well vertical lips are 1.5" high, and it would have been better to go with 2" to 3" as with the 3/4" floor I'll have 3/4" of capture point. With the intensity of the welding fabrication this didn't become apparent until it was done. It feels great to have turned the corner ever so slightly from destruction to reassembly. Cheers.

[Daytonacoupe]

Well, it feels like it's been a year and it's been....more!

I'm closing the loop on the wheel well outcome. Nothing original here as the ideas were pulled from the forum, thanks, but I'm adding a few photos that may help others.

I went with 1/8" aluminum that was bent and welded as per the photos. I don't care for self threading screws, so I drilled holes every 10 inches in the vertical flat bar that had been welded around the perimeter of the frame at the wheel opening, fit the aluminum well and drilled holes that aligned, fit extruded U nuts on the flat bar, and bolted the wells in using stainless hardware. The steel and aluminum contact edges both received generous strips of heavy duty duct tape, and I'll douse the hardware well in fluid film. After caulking I'll spay the outer side with a bed liner or undercoating.

Now it's weather tight as we descend into winter.

Cheers.....

[57Vintage]

Nice job on the wheel wells. That plate should protect a lot if you have a blowout.

[Daytonacoupe]

Originally Posted by 57Vintage

Nice job on the wheel wells. That plate should protect a lot if you have a blowout.

Yes, thank you. I particularly like that this approach isolates the wells from the subfloor material, so if they ever need to come off, the inside of the trailer doesn't have to be dismantled. A great solution for keeping water away from the interior well edges too. The outside aluminum trim strip was slipped on yesterday and fit into place over the same outer skin rivet holes, so the alignment is perfect. Now I'll rivet it and the overlay trim into place and will have to save the caulking for next spring. At least the trailer is now securely weather tight, although I do find that the fridge fresh air vent in the side of the trailer is a nasty ingress point for snow and water when the winds are heavy. I've clamped a piece of plywood over the inside of the louvered vent as a temporary fix. This little gem of a louvered door is an obvious contributor to subfloor rot.