Mounting roof rack to Leer shell

Who here has mounted a roof rack to their shell/cap? I picked up a roof rack off a 1996 Pathfinder, and when I drilled into my 100XR Leer shell I discovered an air gap, ie the roof is built like a double pane window for insulation. I’m thinking it would make more sense to use a hole saw big enough for a socket on the inside layer so I’m not sandwiching the layers, and then cap the holes. Is this others have done it, or did they just run the bolts through both layers and not worry about it?

 

You'd probably get more responses in the forum for shells (https://www.tacomaworld.com/forums/tonneau-covers-caps-and-shells.198/ ) but I'll toss one out.

Firstly, don't try to clamp the two layers together if there is normally a gap, you're just going to cause the fiberglass to crack when it compresses. No idea how thick the fiberglass is on that model but you'd probably get a stronger mount integrating both layers. If it were me, and I'm not an engineer, I'd drill the outermost hole the size of the mounting bolt. The inner hole I'd make larger and epoxy an appropriately thick spacer in place so that you're not crushing the two layers then use a fender washer and rounded nut or something like a Yakima capnut (the first time you bang your head into one you'll know why you don't want a regular nut and bolt sticking down). You want to distribute the force if possible. Most shells are made with a chopper gun so you don't want to go gorilla on tightening the nuts, just get them tight enough. Put a bit of silicon or something like 3M marine sealant in the holes but don't goop it in, it's not necessary.

Put blue painter's tape down where the rack will go and you'll avoid scratching the paint; do your measuring and marking on the tape then start with a small bit and work up to the minimum size you need to avoid chipping the paint or fiberglass.

 

Don’t do that.

You want bolt the rack to both layers of fiberglass.

 

The roof should have a reinforcing cardboard matrix between the inner and outer shells. I drilled right thru both layers and the nuts tightened up just fine with no problems. You could use fender washers on the inside to spread the force around if your worried about it.

 

Some shells are designed to support the weight of a rack. Others are not. If you hit an air pocket yours is not. The top of mine is reinforced with what appears to be plywood between the outer and inner surfaces. The cap is over 1" thick on the top.

 

According to Leer it can support 220lbs: https://www.leer.com/s/faq

Maybe their design has changed? I already drilled holes though. I’m just putting traction boards and a folding table up there, maybe some camp chairs. I figured worst case I build a steel subframe to go inside it and mount it to the bed. Ideally I’d epoxy some sort of spacer in there but I don’t know where to get 1/4” ID composite tubing.

 

Through bolt with washer and locking on back side

 

Maybe just fill the gap around the hole with liquid nails? Lol

 

How much space is there between the inner and outer layer of fiberglass? From your description it sounds like a thin air gap (provides some insulation). If you can't easily get the layers to touch by pushing on the inside layer then you are going to cause cracking in the gel when you start tightening the nuts. That may or may not be an issue on the inside but if you get cracks, even microcracks in the outer gelcoat, you risk moisture intrusion which will lead to mildew and eventual breakdown of the materials.

You can buy spacers at places like Home Depot (Ex. https://www.homedepot.com/b/Hardware-Fasteners-Spacers/Aluminum/N-5yc1vZc2fdZ1z0usgq) and cut them to length. Alternately you could probably redneck engineer it by taping off the inside hole and injecting epoxy gel then redrilling your hole or maybe packing JB Weld in it. Ideally you want some sort of fender washer on the inside to distribute the force (you're going to have some uplift with anything that catches wind

Lots of shells use a fiberboard or cardboard honeycomb section in the middle to reinforce the middle so that it doesn't flex/vibrate (causing cracks in the gelcoat) and doesn't sag over time. You do not want to drill through that without reinforcing it as it will crush over time (according to the Q/A on, IIRC, ARE's website).

 

It’s a small gap, maybe 1/4”. The layers don’t easily touch though. I’m thinking I’ll tape off the lower hole, inject with an adhesive like Loctite PL Max, then re-drill. That sounds like the best plan and will seal the gap better so water won’t ever get inside it.

 

I used a 2part epoxy and pushed it into the hole as far as I could all around. Worked pretty well.

 

Without filing the void in between to create a solid section it'll crack in no time.