This bolt failed, resulting in the failure of a metal structure.

Does anybody here have experience looking at broken bolts? Are there any clues as to why it broke? I believe it was torqued correctly, to specs. There were two bolts, one on each side of a frame, and both snapped like this.

The bolt head says “10.9”.

The top photo needs to be retaken from 2 additional angles:

spin 90 so the fracture face is visible.

top view

Why do you believe they were torqued correctly? What was the torquing device, what was the lubricant, and how was the torque spec determined.

I was involved in the aftermath of an overtorquing incident where it was a Teflon coated bolt that had lubricant applied. Everybody involved turned their brain off because somebody found a chart that said friction INCREASED by adding the lubricant so torque needed to be increased. Turns out the chart was wrong and had been recalled years earlier.

On the bottom photo, the 10.9 means ISO R898
Class 10.9. As far as the EF, it’s the manufacturer ID, but I’m at home on my iPhone and coming up blank on manufacturer name.

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Ego is the anesthesia that deadens the pain of stupidity

DISCLAIMER: These are the author's own personal views and do not represent the views of the author's employer.

quote:

Originally posted by tatortodd:

Why do you believe they were torqued correctly? What was the torquing device, what was the lubricant, and how was the torque spec determined.

Good questions. No lubricant, and I used a torque wrench I believe to be reasonably accurate, but I don't have a way to calibrate it (yet).

There have a been several reported failures of these bolts recently. They are used to fasten the upper "crash bar" to the motor mount and frame of a motorcycle. Multiple instances of these bolts breaking with no reported impacts to the crash bars (just stress/vibration at the attachment point).

The other half of that bolt is in the arm of the frame. It's *supposed* to be lined up with the motor mount. But the bolt sheared, and the whole frame flexed and broke.




The frame looks like this on both sides. I'm not sure exactly when the bolts sheared, but it all happened pretty quick. I was coming down a hill, having ridden some pretty rocky terrain. I stopped as soon as I heard the change in the sound of the suspension, and found the sheared bolts. I didn't find the frame damage until I removed the plastic fairings.

Broken metal parts are observed when a repetitive load creates a fracture that traverses the part, or when a load applied to the metal exceeds its inherent strength.

Complicating factors exist. Corrosion, plating, environment, alignment, and installation all play a part.

If the fastener here was between the engine and the frame, it is likely that a repetitive stress, most often called fatigue, existed on that fastener. Torque alone does not cause fatigue.

The image shown has a fracture that led to a final separation of the fastener approximately halfway across.

The fastener appears to be plated. This is sometimes the cause of fractures, through hydrogen embrittlement. The plating process normally requires an acid passivation of the steel, and hydrogen (the proton in the acid) can find its way into the metal. If the fastener is not processed to remove that hydrogen then fracture is quite possible.

And on motorcycles, vibration can be a factor. I try to check my fasteners several times every riding season.
But in this case, you might not have seen the problem until the bolt actually failed.

fwbulldog, thanks for the torquing information and the additional photo angles. At work, the next step would be for a metallurgical lab to get mechanical and chemical properties of the bolt (i.e. does it meet ISO R898 Class 10.9?) and then starting photographing under magnification and with etches (it'll determine crack origination point and grain structure). Since it's your personal motorcycle, I'll go out on a limb and say that multiple thousands of dollars in metallurgical analysis and testing is out of the question. I'll come back to this in a minute.

Reading between the lines (correct me if I'm reading too far) on your follow-up post, the engine mount bolts were removed and replaced with the longer bolts in order for the crash bars to be installed. The broken bolt connects both the crash bars and engine to the frame.

I'm not familiar with the frame design of your motorcycle (I'm assuming it's the Triumph Tiger you've been posting about). On my motorcycle and many modern motorcycles the engine is a stress member replacing parts of the frame (either entirely or frame in area is designed to be smaller because of motor). This is quite different than the old school frame which carries all of the load and the engine is connected to frame with vibration reducing motor mounts.

I wrote the frame design paragraph to lead up to the $20k question. Were the crash bars 3rd party aftermarket or an accessory from the motorcycle manufacturer?

Hoping it's an accessory from the manufacturer which would make the "several reported failures of these bolts recently" potentially easier as they may be interested in obtaining your bolts for the aforementioned multiple thousands of dollars in metallurgical analysis and testing to see if they need to make a recall. It also means your local Triumph dealer is your initial point of contact.

If it's a 3rd party aftermarket part, there will probably be some finger pointing between Triump and the crashbar manufacturer. Unfortunately, I don't know where to start other than say complaining effectively (i.e. focus on desired results of frame made right/replaced instead of venting frustration) is key.

quote:

Originally posted by tatortodd:


I wrote the frame design paragraph to lead up to the $20k question. Were the crash bars 3rd party aftermarket or an accessory from the motorcycle manufacturer?

Hoping it's an accessory from the manufacturer which would make the "several reported failures of these bolts recently" potentially easier as they may be interested in obtaining your bolts for the aforementioned multiple thousands of dollars in metallurgical analysis and testing to see if they need to make a recall. It also means your local Triumph dealer is your initial point of contact.

If it's a 3rd party aftermarket part, there will probably be some finger pointing between Triump and the crashbar manufacturer. Unfortunately, I don't know where to start other than say complaining effectively (i.e. focus on desired results of frame made right/replaced instead of venting frustration) is key.

Exactly right. The Crash Bars and broken bolts are 3rd party. The bike is (for al practical purposes) totaled. I'm going to turn it into the insurance company as a claim, and am trying to think through any potential arguments they might have to deny the claim.

I carry comprehensive and collision insurance, and I think it would be covered. I will have no recourse against the 3rd party manufacturer, as they are in a different state. If they used sub-standard bolts then my only course of action is likely a social media campaign.

If insurance doesn't cover it I'm out $15K. I can guarantee Triumph would give me the finger on the frame warranty due to non-OEM bolts (and I can't say they are wrong).

The bike only has 8K miles, was only dropped on the crash bars one time, and that was at a stand-still mid u-turn. It didn't even scuff up the bars, and I rode 6K miles after the drop.


I contacted the owner of the company, he said "The bolts are the sacrificial parts to save the engine block. It's worth checking them after drops. Unfortunately the Tiger 900 models do not offer us any frame mounting points, only the engine. "

I removed and re-torqued the bolts before the trip. I had to in order to install the skid plate (same manufacturer). So the bolts weren't broken prior to the trip. They failed during some off-road riding.


At the end of the day I just want the bike back, in working condition. The frame has to be replaced.



Here is how they advertise their bars:

quote:

Originally posted by fwbulldog:
I contacted the owner of the company, he said "The bolts are the sacrificial parts to save the engine block. It's worth checking them after drops. Unfortunately the Tiger 900 models do not offer us any frame mounting points, only the engine. "

That’s a design flaw IF (big if, I haven’t researched) the engine is a stress member where dropping the bolts while driving means dropping the engine which means dynamic loads on the frame. In this case, 3rd party crashguard manufacturer should have tight vendor selection and quality assurance on provided bolts.

10.9 is the hardest metric bolt commonly available. So, domestic equiv is a Grade 8. Harder than the hubs of hell as they say.

Assuming that the part diameter was engineered correctly, then the likely answer as noted up thread is Hydrogen entitlement -likely from an aftermarket supplier buying a plain (unplated part) and sending it to the platers but not specifying a bake. Bake for that item would likely be 4 hours.

The platers would have a record of the bake if it was done there.

Maybe not, but that's the most likely thing. Good luck!

quote:

Originally posted by tatortodd:

quote:

Originally posted by fwbulldog:
I contacted the owner of the company, he said "The bolts are the sacrificial parts to save the engine block. It's worth checking them after drops. Unfortunately the Tiger 900 models do not offer us any frame mounting points, only the engine. "

That’s a design flaw IF (big if, I haven’t researched) the engine is a stress member where dropping the bolts while driving means dropping the engine which means dynamic loads on the frame. In this case, 3rd party crashguard manufacturer should have tight vendor selection and quality assurance on provided bolts.

It's also a long, shouldered bolt compared to how much thread is engaged - at least looks like it is. Can't see how much thread is engaged, but the unthreaded portion looks fucking huge if the thread length is what I think it is. That extra length vs factory might put enough load on it that a 10.9 isn't strong enough, especially in a crash. If nothing else, it cut a bunch of the factor of safety from the original design.

I wouldn't think that transmitting crash loads to a motor mount would be a very good idea, doubly bad idea if the engine is already a frame member as tatortodd suggests (and a lot are).

quote:

Originally posted by fwbulldog:
There have a been several reported failures of these bolts recently. They are used to fasten the upper "crash bar" to the motor mount and frame of a motorcycle. Multiple instances of these bolts breaking with no reported impacts to the crash bars (just stress/vibration at the attachment point).

Methinks this is a trend that will continue. The 'sacrificial' comment makes me think someone has noticed that these bolts break easier than the rest but hasn't put together the why yet.

quote:

Originally posted by snidera:
It's also a long, shouldered bolt compared to how much thread is engaged - at least looks like it is. Can't see how much thread is engaged, but the unthreaded portion looks fucking huge if the thread length is what I think it is. That extra length vs factory might put enough load on it that a 10.9 isn't strong enough, especially in a crash. If nothing else, it cut a bunch of the factor of safety from the original design.

To follow this line of thought. The OP mentioned he added a skid plate from same manufacturer prior to trip. Was there a spacer/washer in the original crash bar design that was removed when adding the skid plate? In other words, did the manufacturer keep the length of thread engagement the same before and after skid plate installation? If not, it’s a design flaw.

Not a bolt expert, but I do work with hardened metals.

The "harder" most things are, the more brittle they become. Less stretch, more snap. No idea if something as small as a motorcycle would present that type of problem, but I know that there are other circumstances where lower grade bolts are used for that very reason.

I'm with a1abdj , the 10.9 bolt has a high clamp/low shear design .
I have seen more failures due to shear than stretch on bolts than I can count and I've worked heavy junk for 40+ years .
Grade 8.8 M or 5 std. will not hold as tight for clamp but will give and not snap.

Any chance these longer bolts are too long and bottomed out in the hole instead of clamping everything together?
The torque wouldn’t mean much in that case and the side loading and cycling could have caused the failure. The shank of the bolt looks like it had a lot of movement or corrosion.
Get the broken bolt out of the hole and look at the end.

quote:

Originally posted by 220-9er:
Any chance these longer bolts are too long and bottomed out in the hole instead of clamping everything together?
The torque wouldn’t mean much in that case and the side loading and cycling could have caused the failure. The shank of the bolt looks like it had a lot of movement or corrosion.
Get the broken bolt out of the hole and look at the end.

Thank you everybody for the responses. Super interesting.

Here is the other half of the broken bolt. Can't bottom out, the backside is open.

The shank took quite a bit of stress due to it being the only thing holding the top of the motor to the frame mount, even having busted threads. There are two identical bolts, one on each side. The left side had completely fallen out, putting all the stress on the shank of the only bolt left. I think the friction load of the frame/mount held the bolt in place despite the break.

quote:

Originally posted by fwbulldog:

quote:

Originally posted by 220-9er:
Any chance these longer bolts are too long and bottomed out in the hole instead of clamping everything together?
The torque wouldn’t mean much in that case and the side loading and cycling could have caused the failure. The shank of the bolt looks like it had a lot of movement or corrosion.
Get the broken bolt out of the hole and look at the end.

Thank you everybody for the responses. Super interesting.

Here is the other half of the broken bolt. Can't bottom out, the backside is open.

The shank took quite a bit of stress due to it being the only thing holding the top of the motor to the frame mount, even having busted threads. There are two identical bolts, one on each side. The left side had completely fallen out, putting all the stress on the shank of the only bolt left. I think the friction load of the frame/mount held the bolt in place despite the break.

This is a view of the back of the left side bolt.

quote:

Originally posted by fwbulldog:
Here is how they advertise their bars:

I had OM crash bars on my 2016 Africa Twin and on my current 2021 Africa Twin. I dropped the 2016 one time with no damage at all. My 2021 has the Ultimate Protection Combo MAX. I hope I never to put them to the test.

https://youtu.be/gZlDeoX7bw4

One use bolts. Once they have stretched in torking that's the end of their life can't stretch them anymore. Replace with new