Danger - Roof Rack Failure

TesLou

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#1
This is for anyone who has purchased the Model 3 roof rack...BEWARE! In fact, if you’ve installed it on your car, I would immediately uninstall it and by no means put any load bearing weight on it; especially a cargo carrier. About 300 miles into my 800 mile trip yesterday, my wife and I heard a loud “pop”, followed a few seconds later by another. It sounded like a couple huge rocks had hit the car but there wasn’t much traffic in front of me to ha e kicked anything up. Since it also sounded like it came from the roof area, I immediately suspected the rack. I pulled off the next exit and, sure enough, one of the crossbars was loose. Luckily, I had decided at the last minute not to use my Thule box for this trip. I uninstalled the bars and squeezed them in the back of the car and I’ll have to haul them around my entire week of vacation. I’ve reached out to Tesla in hopes they’ll warn everyone who has purchased this.
 

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JasonF

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#5
The broken piece doesn’t look like it’s been flexing. Maybe the bolt was over-tightened? This might just have to do with Tesla needing to revise the maximum torque specification for the boots.
 

TesLou

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#7
There was ZERO load on the bars and there has been no excessive pressure put upon them (other than me giving a minor tug a couple of times to ensure they were secure). I hand tightened them very gingerly when I installed them a week ago. It was cold when we left home yesterday morning and it was gradually warming up as we got further south.
 

Perscitus

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#8
Sorry to hear.

Lots of discussion about this over the the other Tesla forums (since late December or so). Latest working theory has something to do with 1st vs 2nd/newer batch of these, people scrambling to find part numbers, etc.
 

TheMagician

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#9
That bracket looks like it’s been cast (vs. stamped). We should have some people here with the expertise to verify. Not saying cast is bad but you generally don’t see that type of failure with stamped, especially in such a short time frame.
 

TesLou

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#10
That bracket looks like it’s been cast (vs. stamped). We should have some people here with the expertise to verify. Not saying cast is bad but you generally don’t see that type of failure with stamped, especially in such a short time frame.
Yeah; it has a weird and cheap feel to it. The wing nuts do, as well. I’m sure I have second gen since I’ve only had this for a couple of weeks.
 
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#15
The latest theory from another forum post is that the j-bolt on one of the batch with a rectangle hole in the middle and those are the one that are snapping. It was built this way to extend the screw thread out a bit mor.
 

ADK46

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#16
Not only do I get the Comet reference, my PhD thesis was in the field of fatigue cracking and my career was in aviation.

The flat piece looks like a stamping to me - I can see from the sheared edges that it was punched out of a plate, then bent. The threaded part was made separately and (poorly) welded to the flat piece. Since it was not fully inserted into the slot before welding, it left a rectangular opening, the corner of which puts a stress riser directly on the weld.

Amateurishly designed, or someone took a bunch of incorrectly manufactured bits and used them anyway - the round piece was supposed to bottom out in the slot a be welded all around.

Still a bit puzzling that it broke. Was there misalignment? Fit-up stress? Salt? (Stress corrosion cracking).
 

TesLou

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#17
Not only do I get the Comet reference, my PhD thesis was in the field of fatigue cracking and my career was in aviation.

The flat piece looks like a stamping to me - I can see from the sheared edges that it was punched out of a plate, then bent. The threaded part was made separately and (poorly) welded to the flat piece. Since it was not fully inserted into the slot before welding, it left a rectangular opening, the corner of which puts a stress riser directly on the weld.

Amateurishly designed, or someone took a bunch of incorrectly manufactured bits and used them anyway - the round piece was supposed to bottom out in the slot a be welded all around.

Still a bit puzzling that it broke. Was there misalignment? Fit-up stress? Salt? (Stress corrosion cracking).
No misalignment and no stress; other than the normal stress associated with holding the bolts in place. One thing I found that concerned me was the amount of water beneath the end caps (where the nuts and bolts reside). I think in time that may have caused issues of another kind.
 

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Bernard

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#18
Not only do I get the Comet reference, my PhD thesis was in the field of fatigue cracking and my career was in aviation.

The flat piece looks like a stamping to me - I can see from the sheared edges that it was punched out of a plate, then bent. The threaded part was made separately and (poorly) welded to the flat piece. Since it was not fully inserted into the slot before welding, it left a rectangular opening, the corner of which puts a stress riser directly on the weld.

Amateurishly designed, or someone took a bunch of incorrectly manufactured bits and used them anyway - the round piece was supposed to bottom out in the slot a be welded all around.

Still a bit puzzling that it broke. Was there misalignment? Fit-up stress? Salt? (Stress corrosion cracking).
Bad metallurgy, getting brittle at low temps (should be a thing of the past since WWII, but...) ? Poor quality control in the supply line?
The weirdly complicated fabrication process (stamp a piece with a cutout, push another piece in the cutout, weld the two) causing permanent stresses in the cutout due to poor tolerances?
The opening at the bottom looks deliberate to me -- it may come from the need to drain the hollow threaded cylinder; if so, the design had not intended for the weld to go all the way round; but then the designer had never learned about stress inducers, which seems odd...

No matter the state of affairs, the design, as you said, looks clumsy -- a combination of overthinking and carelessness.
Given the cost of the rack, using four quality posts with a proven design should have been a no-brainer.
In fact, Tesla should probably have left it to Thule and their ilk, as they had originally intended...
 

ADK46

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#19
The roof racks that were supplied for my (now lonely) Macan came with a torque screwdriver for the SS socket head mounting bolts. German engineers like this sort of thing. Much better than "Do not over-tighten". (They never complete the instructions: "Do not under-tighten, either. Tighten just right. Good luck.") Teslou: did you tighten them just right? ;)
 

TesLou

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#20
The roof racks that were supplied for my (now lonely) Macan came with a torque screwdriver for the SS socket head mounting bolts. German engineers like this sort of thing. Much better than "Do not over-tighten". (They never complete the instructions: "Do not under-tighten, either. Tighten just right. Good luck.") Teslou: did you tighten them just right?;)
Haha...apparently not. I did try to use a torque wrench (see my YouTube vid) but the 8 nm the specs call for were much less than the wrench could accurately measure. But the fact that you’re snugging this up around an expensive piece of glass is enough to make you gingerly turn the nuts no more than necessary. Or that’s what you hope, anyway.