Converting a factory JK/JKU hardtop to modular

[jscherb]

Since the factory modular hardtop already has bolt flanges on the roof and the back panel, the best way to add perfectly matching bolt flanges to these side panels is to make them separately and bond them in place on the new side panels. I've shown how to make the flanges as separate pieces before: http://forum.expeditionportal.com/t...-JKU-hardtop-to-modular?p=2124546#post2124546

I've laid up new flange stock on waxed paper; when it's cured I'll cut flanges to size out of it. I tinted the resin white so no painting will be required later.

 

[unkamonkey]

You do nice work. I've done boat repairs and Olympic sized swimming pools. At the end if the day I looked like a character from a Mickey Mouse cartoon. Big clumps of fiberglass stuck to my shoes and gloves and we don't want to speak of where the dust from sanding will end up.

 

[jscherb]

You do nice work. I've done boat repairs and Olympic sized swimming pools. At the end if the day I looked like a character from a Mickey Mouse cartoon. Big clumps of fiberglass stuck to my shoes and gloves and we don't want to speak of where the dust from sanding will end up.

Thank you.

It's hard for fiberglass work not to be messy, but over the years as I've been doing this I've developed a set of work processes and tricks that minimize the mess. Even so, I still don't really like fiberglass work, for me it's a necessary evil along the way to implementing my ideas and designs, it's definitely not something I enjoy or look forward to doing.

 

[unkamonkey]

I've spent some days in an office pushing papers around or going over plans to estimate costs for projects. I would rather be out in the weather and get something done or run several thousand board feet of wood through a mill to produce a product. Just me...

 

[jscherb]

The flange stock has cured, so I removed it from the waxed paper.

Next I needed to cut the bolt flanges out of it. I usually do this type of cutting using an abrasive disk in the table saw. In this photo I'm trimming the rough edges of the sheet.

I traced the flanges from the first set of side panels I made earlier in this project:

A little work with the abrasive cutting disk and I've got flanges cut to rough size.

After cutting the flanges were cut to approximate shape (they'll get a final trimming after they're bonded to the side panels), I marked the hole locations by clamping the new flanges to the first set of side panels:

 

[jscherb]

With the holes drilled, I bolted the new flanges to the roof and rear panels.

Next, a bead of epoxy is run along the new flanges, and the panels are set in place. I'm doing this with the hardtop upside down to make the work easier.

Panels set in place. Duct tape is used to hold the panels in place while the epoxy cures overnight.

After the epoxy has cured overnight the panels can be unbolted and the flanges will be reinforced because they're not strong enough bonded with epoxy alone.

 

[jscherb]

The epoxy has cured overnight so I disassembled everything. The side panels now have bolt flanges on them that are a perfect match to the roof and end panel flanges.

Next: reinforcing the flanges, with just epoxy they're not strong enough for use on a Jeep yet.

 

[jscherb]

The next step is to reinforce the joint between the new flanges and the side panels. That's done with a first layer of SMC-compatible resin and fiberglass mat, followed by a few layers of fiberglass soaked in ordinary polyester resin. The SMC-compatible resin is necessary to ensure a good bond to the factory parts, but since it's more expensive than ordinary polyster resin and ordinary resin bonds fine to SMC-compatible resin, the subsequent layers can be done with the less expensive ordinary resin. A thin strip of 3/4-oz. mat soaked with SMC-compatible resin is all that's needed to provide a base for the next step:

A close-up of the base strip and the repaired corner.

The tape is on the outside of the flanges to prevent resin from running over them during the process of applying the fiberglass for the reinforcement. Once the SMC-compatible resin begins to cure, the next step is to finish the reinforcement of the flanges.

 

[jscherb]

Finishing the reinforcement of the flanges. As before, I've tinted the resin white so I don't have to do any painting later. I've reinforced the flange with 3 layers - 1 layer of 3/4-oz mat (it's thin so it conforms the sharp corner well), 1 layer of 1.5-oz. mat, and a final layer of 2" fiberglass cloth tape (provides a nice finished look).

Tinting the resin white is a real time-saver, no painting required, here's the finished reinforced flanges:

A close-up of the repaired corner, it's probably now stronger than when it left the factory:

Once the reinforcement cures all that's left to do is trim the edges of the new flanges (I cut them oversize), fixing any minor imperfections on the outside with a little body filler, washing the original dirt off and touch-up with MOPAR hardtop paint. Oh, and redrilling the bolt holes in the flanges, the holes have been covered up by the reinforcement process.

I posted about the technique of using SMC-compatible resin followed by ordinary resin earlier in the thread, it's covered in this post and the one following it: http://forum.expeditionportal.com/t...-JKU-hardtop-to-modular?p=2124542#post2124542

 

[Bam2413]

This is great! Thanks for such a detailed write up. Knowing how to do flanges is huge!

 

[jscherb]

This is great! Thanks for such a detailed write up. Knowing how to do flanges is huge!

Thanks, glad you're finding it useful. If you've read from the beginning of the thread, you've seen two ways to do the bolt flanges - for the first set of side panels I molded them in place on the sides using forms, and then I did the matching flanges on the other parts to join up to those by molding them separately and bonding them on. Each method has it's place, but when adding a flange to match one that's already there the mold separately/bond on method that I'm doing this week works extremely well.

The methods in this thread generally apply when you're modifying existing parts as I've done with the factory hardtop parts; if you were making original parts in molds a better practice is to design the molds so that the flanges are formed when the part is molded - it's stronger and it's less work to end up with a completed part.

Here's an example, this is a JK Safari Cab side panel still in the mold. The flanges are molded along with the part.

Here's a part just out of the mold, the rought edges aren't trimmed off yet but you can see how the flanges were molded at the same time as the panel.

So depending on what you're doing, there are a number of ways to make things like bolt flanges.

 

[jscherb]

All done. I've touched up the outside with MOPAR hardtop touch-up paint, haven't taken the masking off the windows in this photo.

Washed and ready to be assembled with the hardtop, which I'll do soon. More photos to come.

 

[Comanche Scott]

Thosee repairs came out awesome.

Thanks again Jeff for the excellent explanations. The way you are documenting all of this is very helpful on many different levels.

I've been thinking about roof loading and longevity based on my choice of rack system and use.
All the details you've put in this thread has been very helpful.
Plus it's just down right cool to see what you'Re going to do next.

 

[jscherb]

Thosee repairs came out awesome.

Thank you. Fiberglass repair is soooo much easier than repairing bent/stretched sheet metal, I don't know why more people aren't fans of fiberglass and so many are afraid to attempt repairs or mods in fiberglass.

Thanks again Jeff for the excellent explanations. The way you are documenting all of this is very helpful on many different levels.

I hope the detailed instructions inspire people to do their own conversions, or at least to do their own fiberglass repair.

I've been thinking about roof loading and longevity based on my choice of rack system and use.
All the details you've put in this thread has been very helpful.
Plus it's just down right cool to see what you'Re going to do next.

The next fiberglass project I plan to do - rear fenders to match my front fiberglass flat fenders. Although I do have a bunch of other ideas I'm thinking about so one of them may get me more excited than the fenders so maybe the fenders won't be next... stay tuned.

 

[jscherb]

The modular parts for the hardtop. Laying on the floor are the two side panels I just converted. In the background is a quick-release window side panel and the Freedom Panels, one of which has been converted to a pop-up sunroof.

Assembled.

Inside. For the purposes of these photos, I've only used a few bolts to hold everything together so you'll notice some bolts missing.