Jeep Wrangler TJ Hard Top Repairs

jgaz

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The following is information posted by user "jscherb" and can be found at this thread: http://forum.expeditionportal.com/threads/189471-Tj-hardtop-repait



I've used urethane adhesives quite a bit but in my experience they're not as good as fiberglass for a repair like the ones you've got to do to repair a Jeep Wrangler TJ hard top. They do bond well to fiberglass/SMC, but two things are lacking:

- A repair using SMC-compatible polyester resin and fiberglass cloth or mat will be stronger than a urethane adhesive repair because the repair will be reinforced with new fiberglass. A urethane adhesive repair will only rely on the bonding strength of the adhesive but a fiberglass repair will rely on both the strength of the bond of the polyester resin plus the reinforcement of the embedded fiberglass cloth or mat. It is possible to reinforce urethane adhesive joints with a doubler plate bonded behind the repair, but even so fiberglass makes a better repair in my experience.

- Urethane adhesives don't sand or finish well, so you can't easily make a repair that won't be visible on the exterior of the hardtop. They're really a "glue" where a fiberglass repair is the same material as the hardtop and is workable in the same way.

Because Jeep hardtops are made from the SMC variant of fiberglass, you'll need to use an SMC-compatible polyester resin, at least for the layer that bonds to the top. It turns out that once the first layer of SMC-compatible resin has been applied to the repair area (ideally with fiberglass matt embedded in that first layer), subsequent layers can be done in less expensive/more easily worked ordinary polyester resin.

Ideally what you'll want to do it gain access to the inside of the repair area and do the main repair/reinforcement on the inside. I haven't worked on a TJ hardtop for a while, but I believe the area you need to repair is double-walled, so you'll need to cut an access hole in the inside wall so you can get to the inside surface of the outer wall. If you cut the access hole carefully you can bond the cut piece back in place after the main repair is done and use some body filler to hide the fact that you ever cut the access hole. Because you say "the piece is almost off" this suggests that the repair needs to be very strong so doing a repair just from the outside surface of the hardtop probably won't be strong enough to last long term.

I recently did a repair in a JK Freedom Panel which should illustrate the basic techniques to use on your repair. Here's the Freedom Panel damage:

roofdamage1_zps5t6uxvxg-jpg.jpg


The fiberglass is cracked to the point where it's no longer structurally sound and some of the outside skin is actually broken off and missing. The panel is double-walled, so access needs to be gained to the inside to properly make the repair. It turns out that in this case the inner wall was also cracked and broken so with a little more cutting I was able to separate the inner and outer shells for access to the inside of the outer shell.

roofdamage2_zps3vca1dxd-jpg.jpg


In this next photo I've applied several layers of fiberglass mat soaked in SMC-compatible resin to the inside of the repair area. I've used masking tape on the outside to contain the resin and act as a form for replacing the parts of the skin that were broken away and lost in the accident.

roofrepair1_zpsgrvgutnn-jpg.jpg


In this case, since the repair area was small and mostly non-structural, three layers of fiberglass mat soaked in SMC-compatible resin was enough to make the repair, and after those were applied I closed the inner skin and bonded that back to the outer skin with more SMC-compatible resin. The process on your repair would be a little different, since your repair is definitely structural I'd add a few more layers of resin + mat extending out several inches from the crack.

roofrepair2_zpszuce0ysz-jpg.jpg


Once that's cured, the cracks in the outer skin are mostly cosmetic; the structural repair was done on the inside, so the exterior can be cosmetically repaired with body filler, ideally an SMC-compatible filler. Best practice is to grind/sand the crack so that all of the loose fiberglass is removed and a "valley" if made in the surface to put the filler in. Here's the valley sanded along the crack area:

roofrepair3_zpsm8zepkxo-jpg.jpg


I then applied narrow strips of fiberglass mat soaked in SMC-compatible resin to the crack area:

roofrepair4_zps3v1b0nxw-jpg.jpg


Having done that, I used body filler to fill any remaining imperfections, sanded it smooth and painted it with primer followed by MOPAR hardtop touch-up paint.

roofrepair7_zpsuymqdg9r-jpg.jpg


roofrepair8_zpsb57mspgc-jpg.jpg


Almost nothing is "too broken" to be repaired using similar techniques; a while back when I was just starting my conversion of a factory JK hardtop to modular I picked up a broken side panel from a hardtop. It was missing a lot of the top edge of the panel but other than that it if repaired would make a good modular side for my project. It also had a large crack along the bottom edge. This repair was a little more advanced than the one above; for the Freedom Panel I was able to use masking tape as a form to make the repair of the missing fiberglass, in this case a lot of area was missing so I used a wooden form as a "mold" for the area to be replaced. The bond for the new area, and the repair of the crack at the bottom of the panel, were done using the same materials and techniques as the Freedom Panel repair though. Some before and after photos...

2drpanelrepair4_zpsqw3jxw8x-jpg.jpg


2drpanelrepair3_zps46h2uncp-jpg.jpg


Anyway... the damage to your TJ hardtop is definitely repairable, and a permanent structural repair can be done using the techniques described above, particularly:

- Gaining access to the inside of the repair area so the structural repair can be made from the inside. If you cut an access hole in the inside skin carefully enough it can be replaced after the main repair is done and with a little body filler and paint made almost undetectable.

- Using SMC-compatible polyester resin along with fiberglass mat, applied to the inside of the repair area in several layers ending several inches beyond the crack

- Creating a valley along the crack, doing a first layer repair with SMC-compatible resin and strips of fiberglass mat followed by body filler, sanding and paint.

I've used these two SMC-compatible polyester resins with good results:

All Resin: http://uschem.com/index.cfm?page=productDetail&id=143

Evercoat SMC Resin: http://www.evercoat.com/product-deta...art/100864/us/

An alternative to SMC-compatible polyester resin is to use epoxy resin. A good choice in epoxy is West System G/Flex: https://www.westsystem.com/specialty...ughened-epoxy/. Epoxies like G/Flex will actually bond slightly better to SMC fiberglass than SMC-compatible polyester resin, although both types of resin work well. Epoxies generally don't sand as well as polyesters but since most of your repair will be inside that's not an issue.

Evercoat makes several fillers that are compatible with SMC, here's a list of all of their fillers, the ones that are SMC compatible are say so in the description text: http://www.evercoat.com/reinforced-fillers/us/ and http://www.evercoat.com/premium-fillers/us/

You can use ordinary body filler on top of a repair made with SMC-compatible resin though, check the photo I posted of the exterior repair of the crack in the Freedom Panel: I put a base of SMC-compatible resin with fiberglass mat into the crack, and the filler I used on that repair was ordinary filler, I happened to have Shark Bite on hand because I use it a lot in fiberglass mold making so I used that. You can think of SMC-compatible resin as a "primer" for ordinary filler, as long as there's a layer of SMC-compatible on the surface, ordinary filler will stick fine to that. You can apply SMC-compatible resin with a brush as a primer for the filler.
 
I went ahead and edited the original post so that it includes the post from that forum, but cites the author and has the link to the original thread.
 
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Excellent Chris! I wasn’t sure if anything more than the link was appropriate.
 
Excellent Chris! I wasn’t sure if anything more than the link was appropriate.

As long as there’s a link to the original content, it’s fine! Chances are someone will find this helpful in the future.
 
Does it matter what fiberglass is used (if there is even a difference between fiberglass brands..)?
 
On my '03 I had backed into a tree and broke the corner of my hard top. It left a hole about 3" X 6". I called around and none of the body shops would fix it because it was fiberglass, and even the Corvette shops wouldn't do it because of the pebble grain finish.

I ended up fixing it myself with a fiberglass repair kit from a local auto parts store. The repair went well, but after sanding, I was left with a smooth surface. To match the finish, I painted it with pebble grain spray paint made for gas grills, and to simulate the texture, I used a texture roller from Home Depot. I painted the area, and while it was still wet, rolled over it with the texture brush. It took several coats to get the texture right, but I think it came out really well, you wouldn't notice it unless I told you where to look. Although only one side was damaged, I painted the entire corner cap at the dividing line, so I wouldn't have to worry about feathering the color in. Luckily, the gas grill paint was almost exactly the same shade of black as the original color.

The only picture I have is after the final paint. The brush picture is similar to the one I used.

P1060017.JPG


StuccoBrush.jpg
 
On my '03 I had backed into a tree and broke the corner of my hard top. It left a hole about 3" X 6". I called around and none of the body shops would fix it because it was fiberglass, and even the Corvette shops wouldn't do it because of the pebble grain finish.

I ended up fixing it myself with a fiberglass repair kit from a local auto parts store. The repair went well, but after sanding, I was left with a smooth surface. To match the finish, I painted it with pebble grain spray paint made for gas grills, and to simulate the texture, I used a texture roller from Home Depot. I painted the area, and while it was still wet, rolled over it with the texture brush. It took several coats to get the texture right, but I think it came out really well, you wouldn't notice it unless I told you where to look. Although only one side was damaged, I painted the entire corner cap at the dividing line, so I wouldn't have to worry about feathering the color in. Luckily, the gas grill paint was almost exactly the same shade of black as the original color.

The only picture I have is after the final paint. The brush picture is similar to the one I used.

From what I can see, it looks great!
 
Do you have any suggestions for stripped out screw holes on the inside from the brackets that hold down the top?
You need to be more specific. The hard top has holes in the lower flange that hard top mounting bolts go through to captured nut plates. Are the holes in the flange broken out or are you just missing the floating nuts?
 
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Mmm, maybe drill out the holes large enough for one of these to sit with the flange at the bottom, then fill the hole with fiberglass resin? (Put a bolt in it to keep the hole from filling with resin.) That should give you a good solid metal thread that should last a long time.
1XGH6_AS02.jpg
 
Mmm, maybe drill out the holes large enough for one of these to sit with the flange at the bottom, then fill the hole with fiberglass resin? (Put a bolt in it to keep the hole from filling with resin.) That should give you a good solid metal thread that should last a long time.
View attachment 120016
Put a release agent on the bolt during the cure. Made that mistake before...
 
Glad i was cruising the 'how-to's" and found this. I didn't know about the smc-resin/epoxy. I was going to use regular polyester resin and CSM. Don't want to do it twice!
I'm picking up a super cheap, slightly blemished, no-window hardtop for my 99 TJ. Gonna chop it into a hardtop bikini (weather can beat you down 3 seasons a year here in Canada). I've see them chopped at the line at the window, but I want an 'extended cab' because I'm mounting light and speakers in it. Bye bye sound bar. The power speakers installed in the back are good enough when I'm topless or softopped. Going to properly insulate my current top (and install interior lights & speakers) for winter use.
MAN, i love this site!
 
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Thanks for this @jscherb and @jgaz. I will be prepping mine to repaint it, but I have a couple of tweaks that I want to do to the structure beforehand. I've done quite a bit of fiberglass work in the past, and knew that something looked different about the hardtop's build. My plan was to just use standard polyester resin, so I'm glad to see this info.

I have a somewhat related question. With the top being double-wall, I've wondered about drilling an access point and pouring dense, expanding foam into the hole. In my mind, this may serve as some insulating, but most importantly as a sound dampener. Do you or anyone else know of this being done, and have some Pros and Cons info before I commit to it? As you know, once that's done, there's no turning back.
 
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Thanks for this @jscherb and @jgaz. I will be prepping mine to repaint it, but I have a couple of tweaks that I want to do to the structure beforehand. I've done quite a bit of fiberglass work in the past, and knew that something looked different about the hardtop's build. My plan was to just use standard polyester resin, so I'm glad to see this info.

I have a somewhat related question. With the top being double-wall, I've wondered about drilling an access point and pouring dense, expanding foam into the hole. In my mind, this may serve as some insulating, but most importantly as a sound dampener. Do you or anyone else know of this being done, and have some Pros and Cons info before I commit to it? As you know, once that's done, there's no turning back.
I didn't know jgaz reposted that info of mine, but I'm glad he did and I hope it helps people.

As for putting expanding foam inside the dual walls, I wouldn't. The bond between the inner and outer skins isn't always that strong and it's possible that the expanding foam could put enough pressure on the walls to separate the bond between them.

Here's an example of how weak the bonds are, these are JK Freedom panels that were in an accident. The inner shell of the panel was at the rear but when it broken the inner and outer skins separated all the way to the front:

FreedomPanelDamage2_zpst413odpx.jpg


BTW to illustrate that pretty much anything made from fiberglass is repairable, these are the Freedom panels from that accident, parts of both are completely broken out - the adhesive used to join the skins just gave way. The same type adhesive was used on the TJ hardtop.

PanelsBefore_zps7fhzsjcv.jpg


When I received the panels, I did not get the broken sections, so I had to recreate them. Here's the finished result:

PanelsFixed1_zpsqlsdit84.jpg
 
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I didn't know jgaz reposted that info of mine, but I'm glad he did and I hope it helps people.

As for putting expanding foam inside the dual walls, I wouldn't. The bond between the inner and outer skins isn't always that strong and it's possible that the expanding foam could put enough pressure on the walls to separate the bond between them.

Here's an example of how weak the bonds are, these are JK Freedom panels that were in an accident. The inner shell of the panel was at the rear but when it broken the inner and outer skins separated all the way to the front:

View attachment 141012

BTW to illustrate that pretty much anything made from fiberglass is repairable, these are the Freedom panels from that accident, parts of both are completely broken out - the adhesive used to join the skins just gave way. The same type adhesive was used on the TJ hardtop.

View attachment 141013

When I received the panels, I did not get the broken sections, so I had to recreate them. Here's the finished result:

PanelsFixed1_zpsqlsdit84.jpg
Wow. Okay, yeah I see what you mean. This foam doesn't apply too much force when it's expanding, but as light of a bond as that appears, it very well could push them apart. From the pictures, it appears as if they mated the inner and outer skins with very little intention to truly bond them together. Maybe like they completed all pieces, then used a basic adhesive to put them together.

If the inner skin wasn't made up from separate panels, I could understand that motive a little more. But, I don't understand their intention in this case. That seems strange. I can't recall which pieces are stuck together like that on our TJ's top, but I'll look it over and keep your suggestion in mind. Thanks for that info too.