Fiberglass CJ6 tub rear wrap ideas

After a boiling hot summer and many months of illness I am finally ready to resume work on the 74 CJ6 build. I want to start with some work on the fiberglass tub I have. Last summer we had a hurricane and the wind got under the tub and caused a crack that runs down the tailgate opening and across the tub under where the tailgate opening is. Its actually worse now as I took this picture in the spring.



I had someone who is well versed in fiberglass look at it and he is not sure it can be fixed without tearing the back end of the tub apart. I don't want to do that much work on this tub as its not that good of a tub anyways. I have no investment in it and I still want to use it so I am looking for another solution for this issue. We discussed this issue and came up with the idea of grinding a bevel along the cracks, filling them with resin (squirt it in with a syringe), adding some fiberglass sheet and resin behind the horizontal crack under the tailgate (can't get to the backside of the vertical part), then sanding flat. After that I would go to a local metal shop and have a 1/8" thick sheet of steel cut and bent to fit the whole back of the tub. It would be like this and I would add the shape to the wheelwells.



I would then use an adhesive and bolts to attach it to the back of the tub and then cut for the tailgate opening. We figured the metal would add some strength to the back of the tub so it would not crack any worse. I am not concerned with aesthetics as this is going to be a driver not a beauty queen. The tub is going to be cleaned up, the nicks filled and sanded, rattle canned with etching primer, then painted with tan tractor paint from a rattle can. The interior is going to be done with tan monsterliner.

Do you think this is a realistic plan for this repair? The rest of the tub repair is pretty minor (filling holes, nick/chips, and topcoat that flaked off around the holes.

Thanks

Bob

 

I agree with your expert that a "proper" repair more than likely starts on the back side of the crack. With that said, lets move on to the easy way that will get you by!

First, don't use polyester or vynlester resins. Use only and epoxy resin for this repair. What you are looking for is the highest adhesive property you can find, and that is epoxy. Once a resin has set (during the original manufacture of the tub) it is set. Adding resin later in the tubs life does not re-activate the original resin, or create some type of chemical bond, basically you are gluing "something" onto the cured original glass. So, back to the adhesive comment.

I would V-groove the crack to about an 1/8" deep x 1/8" wide with a mini-grinder, Dremel tool, etc...carefully! Throughly clean the exposed glass with denatured alcohol. Use an epoxy resin putty to fill the V-groove and let it cure. Go back with a orbital sander and smooth out the repair area, then paint to match.

I would suggest 1:1 laminating epoxy resin, mixed with some milled fiber and cabosil to make the putty. Try Fiberglass Coatings in Florida (on the web) for your supplies. Or, any marine supply outlet will sell West System epoxies (but they are high $$$) Mix the resins first, add some milled fiber then add cabosil until the mixture is too thick to flow, and will stay in a vertical position....about to the consistancy of peanut butter.

If you choose to add a laminate with cloth, grind down the gelcoat until you reach parent glass and use the epoxy laminating resin + cloth. This will create a strong, permanent repair. Either way, do the V-groove + resin putty first, then go over the cured, smoothed surface with the cloth, epoxy laminate. NOTE: don't add the thickners to the resin when you are doing the cloth, laminate thing....go with the 1:1 as is.

If you only do the putty only fix, go ahead with something else (metal, etc) to provide the strenght.

Good luck.

 

Thanks, that's exactly the kind of instructions I needed. I will be starting this Sunday if weather permits. Its about 70 here during the day and around 50-55 at night right now. Will that cause any issues with the resin?

 

Epoxy resins like 70 degrees. They will set much slower at 55-60, but they will set. Epoxy is VERY easy to use and consistant concerning cure times, unlike polyester that has a mind of it's own!. At 70 degrees you will have "about" 30-40 minutes of working time on a small batch (less than 1 qt). It will start getting tacky and will not become rock hard for another couple of hours, at 6-12 hours it will be functionally cured. it may actually take several days before the mix is 100% cured (no longer off-gasing amines) ...but you can sand, paint etc fairly quickly. Once it's hard (2-4 hours) do whatever you want with it.

TIP: Keep the mixed pot out of the sun, cover it with a towel, etc. Once the mix starts making heat, it will start setting. The hotter the pot, the faster it starts setting.

Good luck