Repairing 4ft Crack on a Thule Motion XT XL "Cargo Box" 

He's not doing a fiberglass repair pr se.He's using fiberglass for reinforcement but he's not using bonding agent which is used to repair fiberglass Fiberglass mat is used for a variety of repairs for reinforcement. Cement, stucco, epoxy, tarps and other kinds of repairs where strong reinforcing is desired are some applications where fiberglass mat strengthens the repair.

Thanks for the response. Yes, the front strut can be removed with a large screwdriver but we drill out the front strut rivets more for the re-attaching process. There are two reasons we drill it out. One is there a reinforcing bar on the inside that doesn't allow us to put the clamp on the backside of the hinge. The other is, the front lip is rolled over and when a clamp is applied, the leading edge of the plastic lip can't support the pressure and is very likely to crack. Once you've worked with rivets, they are simple and hassle free to drill out and install.

Hello, I live in the UK, where did you buy it?

We mainly focus on getting the box back on the road and reducing the amount of waste going into a landfill. For this box, all the repairs were done on the inside and as you can see, the crack is the only thing showing on the outside which is rather hard to see unless you're looking for it. We don't do any cosmetic work, just function.

I find I do less repairs on the Motion series boxes. They seem to be slightly more robust and never have issues with the locks. The achilles heal for the Force series are the locks. I currently have four of the Force series boxes sitting in my shop with lock issues. Most of them are operator errors but none the less they have weaknesses. My rental fleet are all Forces but we give very detailed instructions to our renters. When talking actual strength of the plastic, they are the same. When a box hits a garage or any other low lying structure, it doesn't matter how thick the plastic is, the garage always wins. Enjoy!

​@@robertzeien1895 Thanks you for sharing, I appreciate your valuable insights.

Our kit is unlike the one you mentioned. Our product actually chemically welds the fiberglass to the cargo box and is not a two part epoxy that is considered a surface band-aid. The chemical weld actually slightly melts the cargo box on the surface and then the fiberglass is applied and then another coat on top, as shown in the video. It ends up physically being part of the cargo box and can't be removed with a chisel without outright damaging the box. The fiberglass gives it the structural support it needs under any condition. When the Bondo repair is subjected to twisting and turning, which happens when the cargo box is opened and closed, especially during very cold or hot conditions, it will either crack or start to peel off. Thank you for your input.

What about oatey abs cement? Mammoth mend is three times the price of Oatey

he explained it in the video, that sometimes you can damage the metal post and break it off. there is no replacement part for that apparently.

I see no reason to throw it out. You'd be missing out on the hundreds of dollars that you can sell it for after being repaired plus the aspect of not throwing away something until it can't be used anymore. Just drill out the rivets connecting the strut and do two layers on the inside, re-rivet the strut back on and you're done.

This is a tough one to explain but I'll try and give a brief explanation. I'll be releasing a video soon to show how this is done. Basically we use duct tape over the hole on the outside and then do the repair on the inside where the sticky side of the tape is. The tape and repair won't bond together. After 24 hours has passed you can remove the duct tape. We then do a repair on the outside and once more on the inside to give it a total of three fiberglass layers in total. Give plenty of time for each layer to cure.

You can use wire that they sell at the big box stores. It's by the re-rod in the area where they sell cement bags.

I found some 18-gauge hobby wire at Home Depot that was cheap and worked great@@robertzeien1895 , thanks.

We let the repair set for 24 hours then cut out the wire.

Yes. I plan on putting out a video soon covering this subject. I wrote about this a little bit in @axel6176's comment.

@@robertzeien1895 thanks!

We have developed our own blend that has beneficial additives such as elastomers that help with elasticity and UV inhibitors that stop the UV rays from breaking down the repair.

@@robertzeien1895 do you sell just solvent cement?

All boxes us a 3/16" gauge (size 6) and the length that covers most situations is called "64" which has about 11mm of usable shaft. If in doubt, go longer.

I've had mixed results with painting cargo boxes. Usually after I give it a try, I wish I would have left it alone but then again painting isn't my strong suit.

Correct, It was damaged in shipping and rather than making a warranty claim, which would require us to cut it in half and throw it in a dumpster, we repaired it and made it stronger yet flexible. Granted I couldn't sell it for new price but had no problem selling for 10% off. Are you repairing a box?

@@robertzeien1895 No, just bought one. Never owned a roof box. They do seem fragile though.

@@bluelude2001 It's a fine line between making them durable and not making them weigh 100 pounds. Through my experience, 80% of the damage that we see is by hitting low items like garages. One trick that might help you from experiencing that is to put your garage door opener in the glove box whenever the box is on the roof. If the opener is built in, use a brightly colored piece of tape over the button when the box is up there. Enjoy!

Is there any way I can see the picture of the cracks?

@@melvinsolomon6709 There is a full view of the damage within the first few minutes of the video and an overview of the repair at the end. I don't feel like I answered your question. Can you elaborate on what you'd like to see.