I'm debating mounting one of these style bike mounts just above the rear glass on my hardtop.


It looks like the hardtop is double walled in this location so I cant easily measure how thick it is nor can I easily access the rear to install some large fender washers to spread out the load. Any opinions on drilling and installing some rivnuts in this area? Would I be better off fabbing a bracket that could tie in to the glass hinge mounting area?

Here is where Im thinking of bolting the mount (not my JK, I have the newer style hardtop):

 

IDK.. before I drilled on mine, I would check salvage yards for a wrecked hard top with much damage. You might gain needed info by the removal of the hinges for the window..

 

I'm planning on repainting the whole body at some point soon so Im not super worried about the drilling part as patching a couple of holes should be somewhat simple if need be. That being said, removing the hinges to look around is a good idea! At least I can see what kind of hardware they use. I did see a couple of roof racks use those holes for supporting the rear of the rack so Im guessing its somewhat solid.

 

If you do this put a backing plate on the inside to spread the load.

 

There is an outfit that sells a support kit similar to what Moodyalaskan says. If I can find out who it is I will post a link. But the backing plate is recommended as the top still flexes and that will eventually break it. The kit I am referring to braces inside from the roof to the floor/rollbar system.

 

I think if you search a bit for "jscherb jeep hardtop" you will find a decent array of pictures as that member has, on a few forums, documented some custom hard top designs, and some of the pictures along the way might give you at least a glimpse of what some of the thicknesses are at different points. I know it's not terribly scientific, but at least a visual idea. That is the only person I can think of off the top of my head that has chopped up several hard tops it seems. Here is one link to get an idea -

https://expeditionportal.com/forum/t...odular.160775/

Pictures like this are a nice reminder of what is in some areas -

 

Interesting cross section photo above. For reference, I drilled through that double wall to install a roof basket. Recently completed a 2000+ mile road trip with over 100lbs of gear loaded in it.

 

I drilled a bunch of holes in mine to mount some roof rack rails. The picture above is actually very helpful, I used that section where the double-wall section meets the single, right at that double thickness seam. The rails run the length of the hard top and I used some steel flat stock underneath to help distribute the load. I put silicone in each hole with the bolt, I used rubber washers and bolt caps inside to keep it neat and bump-your-head friendly. It's been up there with snowboards, surfboards, kayaks, camping gear in a basket, you name it and no leaks, cracks or any other wear. It's certainly not a point load anywhere on the top, so that may make a difference.



Inside

 

When I posted I was referring to a mount for something like rooftop tent. Also please remember that if you strike an obstacle like low hanging tree in the bush then you could push the roof in whereas with the bracing you would most likely damage the rack mounted on top which would be my preference.
AnoldUR - you should seal your bolts that you drilled thru there. You can do that by removing the bolts and using gasket sealer then re-install.

 

Thanks for the link! that was a very interesting read regardless of what I end up doing.


Here is what Im currently thinking. If I make a bracket (14ga steel probably) and use rivnuts through the hard top in the locations shown in red then the bike mount should attach in the area shown in green. Any thoughts on whether or not that will distribute the load enough? Im considering trimming the top edge off so that it is just the 3 bolts in a row and not having the extra two on the section that extends outward but that extra support might help counter and torque from the bike mount. I think if I get this just right my glass will still be fully openable plus it shouldnt interfere with my paddleboard if its on the roof rack (still gotta double check that part). Basically looking to create this setup but with a bolt on bracket instead of vacuum cups.
I thought about trying into the factory glass mounts but not only is that harder to fab, Im worried it might offset the glass out a bit and possibly leak.


Bracket concept