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suspension failure on 2006-09 Triumph Daytona 675s / Street Triples

I have had a similar failure on my gpz 550 back in the day. It was first year of "Uni-Track" single shock suspension though, so there is that.

the tabs that the bottom of the shock attached to the steel swingarm were way under -engineered
 
GPzPop said:
I have had a similar failure on my gpz 550 back in the day. It was first year of "Uni-Track" single shock suspension though, so there is that.

the tabs that the bottom of the shock attached to the steel swingarm were way under -engineered
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Oh, you found that out too, didja? :laughing
 
That my friend is scary shit, glad you are ok.
 
Glad YOU are all right!

I had an cast aluminum fork crown fail on a bicycle and it almost killed me. Walkup and Melodia got me 82% of what I sued the manufacturer for, which covered my hospital and medical bills (no insurance at the time), and out-of-work expenses. They are still making their bikes the same way even though there were 9 other cases of the same failure.

Class action seems to be the only way a non-caring corporation will change, and that needs a sufficient class to bring some monetary clout to bear.

I used to be a machinist (not an engineer) and from eyeballing your photos, there is NO WAY that part should be made out of aluminum of that thickness. I've come to believe that "steel is real", for it usually cracks before it fails whereas aluminum fails catastrophically.

Even one such failure is too many, for it shouldn't take statistics to make a case of adequate design. Unfortunately, we seem to live in a world where what's right is replaced by what's expedient; and where justice is replaced by what's economical.

I hope you contact enough other riders with this issue to convince Triumph to recall the part and replace it with a steel one, or one completely redesigned to be safe.
 
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@LectricBill: Thanks, and yeah, I quite share your somewhat cynical world view :)

Some simple analysis shows that the total cross-sectional area of aluminum that failed had a pretty small safety factor for the load it endures. Add to that the concentration of stresses induced by nearby holes. Add to that the fact that, as you noted, aluminum fatigues TERRIBLY and fails catastrophically with cyclic loading which... hmm... anyone with any sense might expect on a suspension. And then add to all that the fact that the aluminum in those parts turns out to be cast (not milled) and 100% pure and not even alloyed with any of the other elements that would strengthen it. It's all pretty mind-boggling.
 
OP, good luck with your goal on this. Glad your ok, you may have saved a life getting the word out. Im sure by now you visited triumph rat dot net. Keep us posted on this.
 
Bertrem, ... OMG ... I'm astounded that this shabby "engineering" can pass beyond the incompetent engineer that came up with it, and then it got past any review of the part.

Cast Aluminum has no molecular discipline in it.

It can (and does) have weak spots. Manufacturing knows this, and makes cast parts (like wheels) Hella thick to serve the purpose.

Forging and rolling process's give molecular discipline to cast aluminum, and those parts can be thinnish.
 
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Wow.

Makes me wonder how long that link would have lasted with my riding style.
 
SFSV650 said:
It seems strange to me that they both popped at once. :dunno
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Well, we're drifting OT here, but what the forensic engineers determined was that the fork tubes were held in the crown by being a press fit. No adhesive. No roll pin. No clamps. No welds. Friction.

The bike was a hybrid and not ridden off road, but it did have front suspension. The theory was that each time the suspension activated (plenty on SF streets!), it acted like an impact hammer and gradually pulled the fork out of the crown.

When there wasn't enough "meat" holding the tubes, under heavy braking, the crown split open on both sides, releasing the wheel and sending my head toward the pavement at 20 mph, where it hit with enough force to not only crack the foam in the front of the helmet (doing its job), but also in the back where my head bounced backward fast enough to overcome the inertia of a very light bicycle helmet, rendering me unconscious for 48 hours among other things. My wife is pretty sure I'm still brain injured!

The crown's wall thickness was 2+ mm and there were visible voids in the casting. Just exactly wrong.
(The last time I looked, they still make 'em the same way.)

Back to the Triumph suspension program...
 
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^ oh gosh, I meant I was surprised that the Daytona parts failed on both sides at once, but by our story sounds plenty horrifying too.

I can't get my head around how pinch bolts hold forks in a triple tree (unlike, say, an old ninja 250 where the bars are a 'cap' bolted above the top of the tree) but that's an even bigger threadjack.
 
SFSV650 said:
^ oh gosh, I meant I was surprised that the Daytona parts failed on both sides at once, but by our story sounds plenty horrifying too.
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It can seem like "at once" , Both sides were stressed, and when the failure occurred on one side,
the other side was over the limit dressed..To fail instantly, as well.
 
fawndog said:
So they used that instead of a conventional link ?
3638912655_b168bcdfae.jpg


Working on a Triumph now, thanks for the heads up.
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The Triumph setup is also conventional. The previous gen Honda 1000RR (and maybe others), for example, uses a single dogbone and a pair of rocker plates like the Triumph. Nothing inherently wrong in that basic design, but that doesn't mean it was executed correctly. It's unlikely (though not impossible) that they blew it on the basic geometry. Just too easy a mechE problem. Maybe the material/QC from the supplier wasn't as specced, and the safety factor wasn't enough to make up for that. Not up to alloy purity, heat treat, or maybe close enough to the exhaust to lose it's temper (ha!) over time.

edit: 2008 CBR1000RR linkage added below.
$_57.jpg
 
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Just looked this up to replace mine before I experience something like this (since I seem to have a knack for random catastrophic failures) - part number is now the same for ALL 675s and 675Rs - which means that not only did they change it on the new models, they no longer even distribute the old version.

You may have already known that, but it's interesting information, especially since they didn't do a recall.
 
BTW... if anyone bought a new 2007, 2008, or 2009 Daytona 675 after April 2008 and would be willing to help me try to force Triumph to recall the defective plates, please PM me as soon as possible (legal deadline is coming up). Your help would be tremendously appreciated and might save someone else a serious injury (or worse :/ )

Thanks in advance!
 
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