Converting a factory JK/JKU hardtop to modular

[jscherb]

I have a feeling your design for the freedom top glass will be a better product the jeetops. Looking forward to it.

There are at least two non-opening Freedom top skylight products on the market - JeeTops is one, the other is JKSkylights. From what I've seen of photos of their products, in my opinion there are some engineering details in both that are not optimal, which probably is why a search turns up many issues.

Example: the ones on the market use adhesive to bond the acrylic panel to the Freedom panel, but unlike standard engineering practice there's no UV protection for the adhesive. Look at the windows in your JK factory hardtop, or your windshield - there's a black coating on the inside of the glass around the sealing surface, that's to prevent UV from damaging the adhesive. Without that protection, failure is assured, especially for something on the roof that always faces the sun.

Making opening windows that don't leak isn't really a mystery if appropriate engineering practices are followed.

My design doesn't bond the glass to the freedom panel (because the glass in my design opens), so the example above doesn't apply to my design. But my design does follow standard automotive engineering practices that apply to opening windows.

 

[jscherb]

A month or so ago I posted about an idea I was working on for openable skylights in factory Freedom panels:

I started on the project today...

I'll be making the prototype skylights out of tinted plexiglass, but once the prototype is done the plexiglass will serve as a pattern for having tempered glass made.

 

[rubicon91]

Very Nice cannot wait to see more of this here.

 

[Comanche Scott]

It would be very cool if the short ribs could be trimmed back, and finished off so that it doesn't look like an after thought (like the non-opening style we discussed before).

I understand for a retail kit that's not practical, but if I was doing this for myself, it is what I'd do.

 

[jscherb]

It would be very cool if the short ribs could be trimmed back, and finished off so that it doesn't look like an after thought (like the non-opening style we discussed before).

I understand for a retail kit that's not practical, but if I was doing this for myself, it is what I'd do.

I have a plan for finishing off the two ribs that were cut, stay tuned.

 

[akpostal]

Looking forwad to this.

 

[ivers]

nice project. how much deep space wouldyou gain with the rear side compartement?

 

[jscherb]

nice project. how much deep space wouldyou gain with the rear side compartement?

If the compartment were to be made like the one in the photo below, it could be about 2 1/2" deep at the top and closer to 4" deep at the bottom. The one in the photo is the same depth top and bottom, but there's more clearance to the roll bar at the bottom that could be used.

There are a few concept drawings of how that could be used in this post: http://www.expeditionportal.com/for...-JKU-hardtop-to-modular?p=2191692#post2191692

But if the compartment were shaped to go around the roll bar like this cardboard mockup it could be a lot deeper:

 

[ACAD_Cowboy]

A month or so ago I posted about an idea I was working on for openable skylights in factory Freedom panels:
...
I started on the project today...
...
I'll be making the prototype skylights out of tinted plexiglass, but once the prototype is done the plexiglass will serve as a pattern for having tempered glass made.

I seem to recall a few years back that someone was making plexi inserts for the freedom top and then they weren't. A trawl of the internet gave mixed reviews about priced too high and scratches & cracking of the panels as well as possibly leakage issues where the glazing and freedom panel join.

I myself would love a nice set of light green tinted lights in tempered glass paired with a matched cloth section on the inside, 3M dual lock to secure it when you want the shade or roll it up and stow it when you don't.

 

[jscherb]

I seem to recall a few years back that someone was making plexi inserts for the freedom top and then they weren't. A trawl of the internet gave mixed reviews about priced too high and scratches & cracking of the panels as well as possibly leakage issues where the glazing and freedom panel join.

You might be referring to Jeetops. A search reveals that they've had a lot of issues with leaking and cracking, and I read that they filed a lawsuit against the manufacturer of the adhesive they used to bond the plexiglass to the Freedom Panel. As far as I know they are still in production, although Quadratec used to carry them in their catalog and no longer does.

One design error I've seen in some production uses of bonded windows is failing to have a provision for shielding the adhesive from UV. Look at your Jeep's windshield or the side windows on the hardtop - there's a black "painted" band on the inside of the glass where the adhesive goes, the main purpose of that coating is to prevent UV light from reaching the adhesive. If the adhesive isn't protected from UV, it will fail over time.

Mine will use tempered glass, there are far fewer problems with glass than with plexiglass. Even if plexiglass/lexan/acrylic did seal properly and didn't crack (which I'm sure it could do with proper engineering), it scratches very easily and over time gets hazy with exposure to UV - being on the top of the roof would make exposure to UV pretty much constant. Tempered glass is no more expensive in reasonable production quantities than the various plastic options, and in many cases is less expensive (sort of off-topic - I can't understand why Smittybilt used plastic for the Alpine windows of their new "Safari Hardtop" for the JK. ok, back on topic...).

Whether you're doing fixed skylights like Jeetops or openable ones like I'm doing, It's really not hard to do them so they don't leak or deteriorate over time. It's pretty basic automotive engineering. Since mine are designed to open, I've designed them to use automotive materials and practices that have been used on flip-open vent windows for decades. Same as I've done on the JK Safari Cab flip-out vents (the engineering and design of which was borrowed from the late '70's Toyota FJ40 and also the skylight design has some parts borrowed from the '90's Ford F150 extended cab vent windows)...

I myself would love a nice set of light green tinted lights in tempered glass paired with a matched cloth section on the inside, 3M dual lock to secure it when you want the shade or roll it up and stow it when you don't.

I haven't decided if I'll implement shades on this prototype or not. I've got a few ideas for securing cloth shades on the inside. A simple way to do it would be to use snaps or twist-lock fasteners, or they could be secured with velcro, or there are a few other curtain fastening systems from the marine worls that would work.

 

[jscherb]

Since I don't plan to remove the Safari Cab from the JK to try out the skylight Freedom Panels, I've set up the JK2 modular hardtop in the spare room again so I can put the panels in place on the hardtop. I've only modified one panel so far, once that prototype is complete with a temporary plexiglass skylight I can get tempered glass made and convert the other panel. A few photos:

The hardtop also currently has a quick-release removable side window installed.

 

[Comanche Scott]

Definitely like the way you trimmed back the ribs to give a smooth mounting surface.

 

[jscherb]

Definitely like the way you trimmed back the ribs to give a smooth mounting surface.

Thanks. My goal was to modify the ribs in a way that they might look if skylights were a factory option.

Other than trimming those ribs to make a flat mounting surface, the project is very straightforward and something I think most DIY-ers could easily accomplish if they were given a kit that included the tempered glass skylights, the weatherstripping and the hardware (hinges, latches, etc.). Trimming the ribs to make a flat mounting surface isn't particularly difficult, but it does require a little work.

My design goals for the project are (in this order):

1. Skylights must not leak.
2. Conversion (if a kit) should be affordable.
3. Should be possible for most DIY-ers to do the conversion.

Probably it would take having a typical DIY-er do a conversion to test and see if goal #3 is met. I'm very confident that goals #1 and #2 will be met.

 

[Comanche Scott]

Not sure what you used to finish off the ribs, but it came out very clean.
On painted tops there would need to be a bit of a repaint around the ribs, unless an exterior frame could be bonded in place. That would also resolve the issue with trimming back the ribs, and the re-paint required to make it look factory. maybe the gasket could be part of the frame, making the whole process one step easier.

 

[jscherb]

Not sure what you used to finish off the ribs, but it came out very clean.
On painted tops there would need to be a bit of a repaint around the ribs, unless an exterior frame could be bonded in place. That would also resolve the issue with trimming back the ribs, and the re-paint required to make it look factory. maybe the gasket could be part of the frame, making the whole process one step easier.

I did a bit of touch-up on the ribs, the MOPAR hardtop paint http://www.quadratec.com/products/92156_2903.htm) is an excellent match.

I considered a frame and rejected it for several reasons - first, it would add significant cost if this were to become a kit - not only for the parts, but for the tooling required for the frames. Also a frame could possibly provide more opportunity for leakage than the way I've designed it, and "no leaks" is my #1 design goal. And making the gasket part of the frame really doesn't make the installation any simpler than the gasket I'm using. Stay tuned, I think when you see the final installation all of that will make sense.