cracked my bed

Its a polyester resin sheet molded composite. From
http://www.fibreglast.com/product/fiberglass-repair-composite-repair/Learning_Center

What about SMC? How do I repair SMC?

• Sheet molded compound (SMC) is a composite material that is frequently used in the automotive, industrial, and personal watercraft market. SMC poses unique repair problems, so we will discuss it briefly.
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  • First, it’s important to recognize SMC as different from other types of FRP composites so that the proper repair can be performed. Parts made with SMC are typically produced in compression molds, causing them to be smooth on both the inside and outside—typically the first clue to identifying them. Next, SMC parts do not have an outer gel coat, rather they are typically color molded and sometimes painted. Finally, when the paint is sanded from SMC, short coarse fibers are exposed and the dust that is generated is dryer and more powdery than other composites. These hints will make it easier to identify SMC.
  • Next, you need to select the correct resin. While SMC is a polyester—based material, it cannot be repaired with polyester resin. This is due to there being a mold release agent present throughout the entire SMC part. Unlike conventionally molded parts, where release agents are applied to the mold surface, SMC is compounded with a release agent dispersed within the resin mix for faster processing. This means that as the damage is sanded to prepare a good bonding surface, fresh release agent is exposed. Polyester resin products do not offer a strong enough physical bond to adhere to this surface. Because of this, SMC should only be repaired using epoxy—based resins, fillers, and adhesives.

 

This is correct.

/thread

 

Per the link above that is not correct.

 

Fine. Folks often or even typically repair polyester resin GRP with epoxy resin anyways. You'll see entire flame wars on boat repair thread devoted to the topic: "Polyester or Epoxy Resin for repair?"

So, I stand mildly corrected and issue the following REVISED and CORRECTED advice:

grind, sand, tack cloth, epoxy resin, cloth, squeegee, dry, repeat as desired.



I didn't bother to re-read this thread after this most recent bump - but if it wasn't said before, this will is how you create a functionally strong but aesthetically ugly repair. If you want it to be beautiful, you're going to need the pros.

 

Is this still holding up well?

 

I would say it has held up comprable to linex or rhino. It has peeled it some spots where i have hauled tree stands and metal angle and tubing. I wish i would have done it a few more coats but im still pretty happy with it, im plannin on doin my whole truck one day

 

www.monstaliner.com

 

Doesn't look like you removed the bed liner. Are my eyes playing tricks on me?

Be careful people disappear when doing this!
https://www.tacomaworld.com/threads/truck-painted-with-bed-liner.387804/8

 

Ive checked in to that a lil but like raptor a bit more its super easy, looks good, hold up good, and is cheaper. Theyre really close , both epoxy with uv protection and apply with air compressor.

 

2nd gen has no bed liner to remove. Composit bed i took of the top rails also subscribe and awaitin a story in that thread

 

I guess I never realized that it is composite. I'm waiting on a story too.

 

Just wanted to post some pics of what I'm looking at, crawled under the truck to see how bad it was on the other side


This is I between the cab and bed


While I was under there I also found this at the pass side wheel well

Didn't even realize it was there, this is what it looks like from the bed

Kinda bummed out about it. I'd like to fix it as best I can. I know it's just the bed of a truck and I don't really care about scratches and gouges in the bed, but the ones that broke through are on my mind.
Anyone else have broken through gouges? Common? I worked my 13 a lot harder then this one but I don't remember having any break through, never really checked tho.

I'm more worried about it weakening the bed and spreading with more use.
I'm a mechanic so having engines, trannys, engine hoist, just generally heavy car parts/tools isn't uncommon to find in the back of my truck on any given day.

And found some more stress fractures through the other side wheel well as well, not as bad tho

 

A can of that crap they sell on TV to seal up the boat hull with after firing freekin' cannon balls through it aughtta do the job! They wouldn't yank our chains over something like that

 

I used JB weld to fill a 1.5" hole a tire carrier left in my bed, held up great.

 

Just found this article about SMC repair and there were a couple of points that surprised me. First one is that, unlike fiberglass, we can't just back the area with matting or cloth then fill the crack. Second is that oils, grease, and silicones can leach into the SMC making it unrepairable. Of course good enough forva DIY job might be completely unacceptable result for a professional shop.

http://www.searchautoparts.com/abrn/technicians/training/age-automotive-composites

The repair of composites though is unique. For example, SMC and carbon fiber composites are fiber rich materials. As such, a backing patch can't be put on the backside and simply fill the front or cosmetic side with body filler because of thermal expansion and contraction. If you have a fiber-rich part and you do a resin rich repair in the middle of that part, you can't expect the repair area to expand and contract at the same rate as that part. You must control the repair area by using a repair adhesive made for SMC repair and packing as much fiberglass cloth into the repair as you can. This will simulate the fiber rich part, which will expand and contract similar to the original material. When this is not done, a bullseye or halo effect results a few weeks after the repair is completed.

There are a few situations that may make fiber-rich parts not repairable since the fibers in these materials are not 100 percent saturated with resin. This can be an issue if the part has been contaminated with an outside substance. Consider a moderate front-end accident on a vehicle with an SMC hood. The hood sustains minimal damage but the core support is damaged, severing one of the air-conditioning high-pressure lines. The Freon escapes, wetting down the SMC, and it also carries the lubricating oils to the backside of the SMC and the fibers "wick" the oil in. Even though the damage to the hood was minimal, it may not be repairable due to this saturation.

Another issue that can cause a nonrepairable situation is the use of silicone-based products such as interior dressings. Some owners of show cars will spray the engine compartment with these products for that shiny look under the hood. However, this results in silicone leaching into the SMC.

- See more at: http://www.searchautoparts.com/abrn...ge-automotive-composites#sthash.3LuKTW1P.dpuf

 

Time for a flatbed