Converting a factory JK/JKU hardtop to modular

[jscherb]

Sneak preview on the openable Freedom Panel skylights... I made a template for the glass out of plywood today so I could get the hardware installed and get the dimensions of the glass finalized. Here are a few photos of the plywood panel installed.

Tomorrow I plan to make and install a tinted plexiglass prototype sklight to replace the plywood, more photos then.

 

[Comanche Scott]

That gasket works just like the frame I was thinking of. So yeah, absolutely no need.
Very cool Jeff!

 

[jscherb]

A plexiglass prototype skylight installed in the Freedom Panel. More photos to come.

 

[jscherb]

Some shots in place on a hardtop.

Some inside views:

A closer top view from outside:

A video showing the latch. The latch I've used locks in both the open and closed positions.

 

[IdaSHO]

Super cool stuff :ylsmoke:


hard to see from the pics and video, are there any provisions to adjust clamping pressure from glass to gasket?

 

[jscherb]

Super cool stuff :ylsmoke:


hard to see from the pics and video, are there any provisions to adjust clamping pressure from glass to gasket?

The latch has an adjustment for clamping pressure.

 

[IdaSHO]

Nothing on the hinge side at all? Shims perhaps?

 

[jscherb]

Nothing on the hinge side at all? Shims perhaps?

Yes there are shims under each hinge; adjustment on that side would be by substituting a different thickness shim. If you look at the photos taken from the inside you can probably see where the shims are under the hinges.

 

[djb_rh]

How would you envision the DIY person cutting the holes for the windows?


--Donnie

 

[jscherb]

How would you envision the DIY person cutting the holes for the windows?


--Donnie

The best way to cut fiberglass (and fiberglass variants like the SMC the factory hardtop is molded in) is with abrasives.

I cut the straighter lines in this one with a 0.045"-thick abrasive cutting disk in a 4 1/2" angle grinder, and the corners I cut with a 1.5" diamond-coated cutting disk in my air die grinder, then smoothing the cuts and corners with a 2" sanding disk in the die grinder.

A DIY-er without access to those tools could use a handheld jigsaw with an abrasive blade in it (not a blade with teeth). If you couldn't get an abrasive blade, then a fine-toothed metal cutting blade would be ok, but abrasives are always preferable with fiberglass. Blades with teeth can cause "micro-cracks" in the fiberglass due to the impact of the teeth, and these cracks could expand over time.

 

[Yuke]

Still hunting for a cheaper hard top to do this. I would love a project for winter.

So many questions will be asked lol

 

[jscherb]

I did the skylight mod on a late model set of Freedom Panels. The same mod is possible on the early model panels, but due to the differences between the years, the early model panels are a little more work.

On the late model panels, the center is cut out along the joint line on the inside between the inner and outer skins, just follow the joint line. The same cut on the early model panels has no natural line to guide the cut. The cut can be in the same place, it would just have to be located manually, perhaps with a template.

Also, to make a flat mounting surface for the skylight, on the late model panels the ribs have to be flattened in two places towards the back of the panels (circled). The ribs on the early model panels start much closer to the windshield than on the late model panels, so they'd have to be flattened at the front of the skylight as well.

The same parts (skylight, hinges, latch, etc.) can be used on both early and late model Freedom Panels, but it's slightly more work to do the mod to the early panels.

 

[ReconH3]

Awesome as always! I think I would prefer the plexiglass over the glass for weight.

 

[jscherb]

Awesome as always! I think I would prefer the plexiglass over the glass for weight.

Thank you.

You may prefer it for weight, but it will likely leak over time. Acrylics like plexiglass and lexan are flexible. When pulled down against a gasket as in this implementation, the plexiglass will press most firmly against the gasket at the point where the latch pulls it down, but will flex up towards the edges due to the pressure of the gasket from underneath, resulting in a loss of pressure at the edges. Tempered glass will not flex and will exert uniform pressure on the gasket everywhere around the perimeter. This is why all along I've planned for the skylight to be tempered glass and planned for the plexiglass to be just a prototype and to serve as a template for the glass.

Installing multiple latches would also reduce the flex issue somewhat (and could make opening the skylight inconvenient), but with plexiglass there will always be flex and there will always be places where the plexiglass exerts less pressure on the gasket than is desirable.

You could use thicker plexiglass to reduce the flex, but what I've used is 1/4" thick so going thicker would make the skylight stick up even further and the thicker you go the closer you'd get to the weight of tempered glass anyway. Or you could vacuum-form it to have a slight domed shape; the shape would reduce the flex, but that might not be a desirable look for this application.

Besides the fact that unframed flat plexiglass will eventually leak in almost any implementation where a window opens like this, all acrylics are prone to scratching and prone to UV damage - an acrylic skylight would cloud over time the same way that the acrylic headlight covers of cars cloud over time.

And finally, for this application, in production quantities tempered glass is less expensive than quality acrylics.

A piece of tempered glass that's less than 16" wide x 24" long isn't very heavy anyway.

All of the above are factors that early on went into my design decision that the final version needed to be tempered glass.

 

[ReconH3]

Makes sense. Thanks for clarifying.