We just saw video of a car hurled off a cliff with a roll cage held together by duct tape. The results weren’t pretty. Then you see the same stunt again, using a cage made with a multipurpose repair material called “FiberFix” which the video’s advertising. It survives the fall! So is it real or what? The project’s technical engineer takes us through it.

In case you don’t know what we’re talking about, here’s the video ad:

For a little more background, FiberFix is pretty much like a resin-reinforced repair tape that’s supposedly capable of withstanding liquid, extreme temperatures and heavy impacts. You probably got that if you watched the ad.

The stuff has actually been around for a few years, makings its “public debut” in 2013 on . Heck, you can (decent reviews!)

FiberFix’s main claim is that it’s “100 times stronger than duct tape,” though back in 2013 inventor Spencer Quinn (a Brigham Young University student at the time) told it’s actually “significantly stronger,” holding 2,000 pounds in a load test that killed duct tape at 100 pounds. I guess it can also go higher?

I don’t know about you, but I hadn’t heard about the stuff until this morning. Apparently I wasn’t the only one, hence the expensive commercial. Now that we have heard of it, I want to know if it really can coddle a car falling off a cliff.

The Harmon Brothers, the outfit that shot the ad, anticipated that and already has a pretty comprehensive behind-the-scenes breakdown up:

Initially their plan was to make a Jeep roll cage out of PVC plastic pipe, wrap it in FiberFix, send the thing to Moab and try (not to) hurt themselves. But the mechanical engineer they hired to do a feasibility study refused to sign off on the project based on what I can only assume was “common sense.”

“We decided, well, I guess we just have to start testing,” said Harmon Brothers’ technical engineer Benton Crane.

They wrapped all kinds of products and piping in FiberFix and subjected to a battery of endurance tests until they were satisfied enough to bring it to professional roll cage engineer Deveren Farley.

He was skeptically willing to build the cage, presumably provided he was promised nobody’s life would depend on it, and once the shape was tack-welded together the joints were locked in with FiberFix for the crash.

Four test cars were built in total. The cages were welded to the underside of the car, but held together completely by tape or FiberFix. Tack welds were used to set the cages into place, but ground down in “final assembly” leaving the tape or FiberFix as the only adhesive item keeping the respective cages togethe

The yellow car (with the duct tape cage) and the red car (with FiberFix) both went off the same cliff at the same speed: 25 MPH.

Crane was kind enough to go into a little more detail about the specs of the vehicles and the cage in an email:

“The cars used were Geo Metros stripped of engine, transaxle, radiator, gas tank, and glass. The steering and brakes were both left intact and functioning.”

“The rollcages were made of 2" OD .120 wall HREW steel tubing.”

“A foundation for each roll cage was welded to the under-belly of each car. The foundation has 8 mount points that protrude out from the underside of the car. The cages were built on these mount points.”

“The roll cages were built and assembled using small tack-welds on each joint. This means there was one tiny weld on each joint, just to hold the cage together during construction.”

“We used an angle grinder to completely remove each tack weld prior to applying tape. Because the welds were completely removed, each joint was 100% held together by tape, and only tape.”

“We used 2x more duct tape than FiberFix. Each “T” shape joint had 40 yards of duct tape or 20 yards of FiberFix. The “X” shaped joints each had 50 yards of duct tape or 25 yards of FiberFix.”

The moral of the story is “don’t make your roll cage out of any kind of tape” but holy crap, this tape is pretty strong.

If you’re curious about how the stuff works in slightly more practical applications, FiberFix also has far less entertaining but more informative videos on their product in action too.

Seems like a significantly better result than duct tape at a higher cost and slightly greater inconvenience. Then again, slightly greater inconvenience. Anyway “mystery solved” on the roll cage. Has anybody actually used this stuff?