fiberglass body repair

[thistle3585]

I just picked up a rolling chassis with a fiberglass tub and tilt front end on it. The PO had cut out the center raised section, between the seats, of the tub which covers the Transmission etc. I'm wondering what my options are to repair it? Is there anyplace that would sell fiberglass parts? I wondered about fabricating something out of diamond plate. Any thoughts or ideas?

I was told that this was a CJ7 chassis, but I'm starting to think it may be a YJ. I need to locate the VIN in hopes it will give me an idea of what it is.

 

[rufus1138]

get some foam or something easily shaped and make a template, then get some fiberglass and compatible resin/hardner and lay it up one layer at a time till its about as thick as the body in that area, trim this to a general fit with a little bit of gap (approx 1/8 better if its 1/16) then use shims and blocks that will be easy to remove and place the new part in its home and get it to set nicely.

now you have to sand the edge of the original body and hole down to bare glass, make it fuzzy for about an inch or so around the hole on both sides, get the new piece in place and start taping (with new glass and resin) around the perimiter of the mating surfaces on the bottom, make sure you get full impregnation of the material and bonding surface. after this kicks all the way you need to spackle the crack that now has a bottom to it full of thickened epoxy using structural high density filler material (u can get this off the shelf or chop some fibers yourself, its all an art form) after the gap is filled repeat the taping procedure on top then sand and fair out the seam you have made and if any gaps or holes show up hit them with tape if they look weak or fill them with high density filler if it seems minor.

with the fitment of the new part make the gap larger if you're going to use hand chopped fibers for filler material, if using store bought high density stuff then make the gap as small as possible and mabey chamfer the edges to make it easier to fill without making a bunch of voids.

if you have a west marine store nearby it will be expensive but the best materials you can get that are also stupid easy to work with are west system products. also when you make a negative template to lay the initial replacement tunnel cover onto be sure, absolutely sure, to use a lot of mold release, make sure that doesnt bond to the template, the guys at westmarine can help a little especially with things like compatibility of materials.

if you decide to do this i can walk you thru it on here with pics and some phone calls, its easy and like i said artistic, and if you have a fiberglass body this can be a huge skill set to know well to make repairs in the future, you will be much less worried about chunking out a panel on the trail once you get confident with making fg repairs.

 

[thistle3585]

Thanks. I'm very familiar with the epoxy process, as I have done a considerable amount of boat repair, but I wondered if there were companies that my sell panels like they do for sheet metal bodies. Seems like you could get just about anything for those. I think my problem is having to track down a body to use to make a mold from. I'm going to check the salvage yards first and see what I can find.

 

[rufus1138]

lol sorry i tried to assume no knowledge, worst case scenario. should be able to make a template from the junk yard easy enough, personally id just make something that fit good enough and has some flat areas to mount cup holders.

 

[Jimbos76cj]

Yj and Cj frame are very different. Do the shackle bushings bolt to the frame or go through it? Do the front shock use a post style tower or a stud that comes off the frame? Picks of either of these areas will get you a good answer.

 

[thistle3585]

Yj and Cj frame are very different. Do the shackle bushings bolt to the frame or go through it? Do the front shock use a post style tower or a stud that comes off the frame? Picks of either of these areas will get you a good answer.

The frame has been modified too much for me to answer that question. The PO reversed the springs and put the brackets on the ends and the shackles in the middle. Not sure what is going on there. I am going to be pulling the tub this weekend and take a picture of the frame and post it. I'm hoping that I can find the frame VIN and determine from that what I have.

I have a friend with a CNC. He said he could probably draw the "hump" in CAD and cut it on his CNC out of foam so that I can mold a new one. I need to track down a tub to get proper dimensions.

 

[bptactical]

I have a friend with a CNC. He said he could probably draw the "hump" in CAD and cut it on his CNC out of foam so that I can mold a new one. I need to track down a tub to get proper dimensions.

Your over thinking it. Just go get some metal screening from the hardware store, not the wimpy screen door stuff, get what they call hardware cloth, the squares are about a 1/4".
Cut a piece a few inches larger than the hole you want to fill. Put it on the underside of the body and form it into the shape you want. Remove it from the body. Cover the topside with duct tape or the aluminum duct tape works really well. Put a couple of coats of wax on the taped surface.
Now you have a "plug" for the repair. Prep the topside of the repair area by feathering out the area about 6" around the hole.
Now put the plug back in place and hold it up with more duct tape and prop it up if needed.
Cut your glass mat the same size as the hole for the first layer and each subsequent layer should be about 2" larger than the previous one. If you want extra strength you can do a layer or two of cloth but keep in mind it is harder to lay into sharp contours. After about 4-6 layers you should be flush with the finished surface of the tub.
I wouldn't use epoxy resin unless the tub manufacturer used epoxy on the original lay up. Most don't and used polyester.

 

[thistle3585]

Thanks. Yes, I am guessing they did use polyester. I didn't think of the screen idea. That's great. Now what I'm thinking is using some thin pre-impregnated sheet material and push that into the opening to get the shape I want then simply glassing it in. I could probably spray a final layer of gelcoat, but not sure if that is necessary.

I have a couple other issues too. One being, they cut out the seat support and the other being that the windshield frame sags in the midddle. I'm thinking I might glass in a block for the seat mount. You can see the windshield sag in the photo. What I'm wondering is if I need to fix that sag or if I can rely on the dash to take it out when I mount it or a little of both?

 

[bptactical]

I would bond and glass in an aluminum angle for the windshield frame. You get the bonus of having a great big grounding bussbar too.
Rough up the underside of the body and bolt it in place, glass it in.
The thing with 'glass, you really don't want to rely on it for structural support unless you have a supporting structure. The dash has a fair amount of weight on it and you will crack the body where it bolts in.
As far as the seat supports if you are going to use a block, make it out of good quality plywood, much stronger than plain wood. Glue it in place with composite body panel adhesive prior to glassing it in. Polyester resin is a poor adhesive.
Personally I think I would make a framework out of 1" square tube that bridges the center tunnel. Spread the load and make it a structural brace for the body. With the extent of material removed by the PO the tub has very little structural integrity.

 

[thistle3585]

Thanks. The PO actually did reinforce the tub with aluminum square tubing where it was cut out. I'm not really sure where they were going with this project. They didn't use traditional body mounts. They welded square steel tubing on to bring the body to the right height then bolted the body directly to the steel tubing.

In regards to the windshield, there isn't much room under the windshield to mount anything because of the way the tub was molded. I'm guessing the windshield bowed because the center of the tub was cut out. I'll see what I can do.

I do have a friend with a fiberglass shop who does boat repair that will help me out.

 

[thistle3585]

After having given it some thought, I'm thinking about making the "hump" flat on top so that I can easily mount a storage box between the two seats. Any reason not to do this as long as I give the proper clearance below for the drive shaft? Also, with a 3" body lift is there any reason I can't make the "hump" shallower?

 

[rufus1138]

as long as you clear everything i dont see any reason not to, ill likely do the same if i ever have to replace my tunnel. flat surfaces in the right paces just make things alot easier.

 

[mtnwhlr]

3" body lift with a fiberglass tub

 

[cj7inthetwigs]

I wouldn't change the height in case the body lift ever comes off, imagine that ordeal

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