Gixxer K7 totalled (frame snapped in 1/2)

[Pwalo]

I guess the answer is not to be a twat and ride your brand new Gixxer into a wall WFO.

Seems quite simple really.

[JayRacer37]

Well, hang on all you guys that are going on about weak weld points - remember the Japanese have been playing with optimum frame flex over the past 15 years..where is the best place to engineneer this controled flex in?? Its very easy to change and control the constancy of a weld, this makes it a perfect place to do that surely??
And yea, it may make that weld in particlular weaker than the rest on the frame, but if it is designed to act as the 'hinge' then it would right??
Also, it would be unlikely the frame would snap behind the foward engine mounts, as it has the motor acting as a stressed member holding it together down to the rear mounts and swingarm pivot.

[SPman]

none of my frames snapped.

every other fucking part did though.

Even the plug spanner..........

[Toaster]

Suzuki's breaking huh??? I'll expect mine to collapse under it's own weight then.

[ManDownUnder]

where is the best place to engineneer this controled flex in?? Its very easy to change and control the constancy of a weld, this makes it a perfect place to do that surely??

Na, too many variables in a weld to accurately determine its elastic behaviour afterwards. I may be wrong, and I know the welding gear these days is GOOD... but I'd expect anything contributing to flex to be a longer member of the frame, cast/built with specific forms to add/control resistance to movement.

Flex on a joint is a "local". If riveted it works because the shaft of the rivet provide a point of rotation, albeit for incredible minor movement. A weld does not... at all (what was the class of ship in WWII that kept snaping after they introduced welded hulls in place of the riveted ones)?

That's where they learned that lesson.

To me the fact it snapped there says a couple of things
1) For the type of impact suffered, that weld was clearly the weakest point
2) the linear failure... down the middle of the weld, is unusual (to my eye anyway) and goes against what I learned of a weld being stronger than the bits it was attaching.

Perhaps it's a built in point of failure that prevents something more sinister happening? Who knows? I'd be surprised if that was the case. To me it looks like bog all penetration or (as someone else suggested) a boundary fusion issue caused by incompatible alloys refusing to fuse.

[FilthyLuka]

hmm... i wonder if you could just pull a dodgy and fix0r it with some grinding and new welds....

ill give you $50 bucks for it

[JayRacer37]

Na, too many variables in a weld to accurately determine its elastic behaviour afterwards. I may be wrong, and I know the welding gear these days is GOOD... but I'd expect anything contributing to flex to be a longer member of the frame, cast/built with specific forms to add/control resistance to movement.

Flex on a joint is a "local". If riveted it works because the shaft of the rivet provide a point of rotation, albeit for incredible minor movement. A weld does not... at all (what was the class of ship in WWII that kept snaping after they introduced welded hulls in place of the riveted ones)?

That's where they learned that lesson.

To me the fact it snapped there says a couple of things
1) For the type of impact suffered, that weld was clearly the weakest point
2) the linear failure... down the middle of the weld, is unusual (to my eye anyway) and goes against what I learned of a weld being stronger than the bits it was attaching.

Perhaps it's a built in point of failure that prevents something more sinister happening? Who knows? I'd be surprised if that was the case. To me it looks like bog all penetration or (as someone else suggested) a boundary fusion issue caused by incompatible alloys refusing to fuse.

Well happy to be shot down by an argument as solid as that one .
Perhaps Suzuki are just looking for places to save more and more weight...as you'd expect.

[Grub]

I'd be very interested to see a qualified forensic analysis of that weld, it just doesn't look right

[The Pastor]

maybe they are using some kind on new light weight metal that doesnt change when it gets welded or somthing like that? That could explain it, but from those pictures, im not buying a zuki untill i feel they can actually stay together.

[The_Dover]

maybe they are using some kind on new light weight metal that doesnt change when it gets welded or somthing like that? That could explain it, but from those pictures, im not buying a zuki untill i feel they can actually stay together.

yeah, by the time they suss out the durability you might have saved enough for a GN

[The Pastor]

yeah, by the time they suss out the durability you might have saved enough for a GN

so true

[Fooman]

Well, hang on all you guys that are going on about weak weld points - remember the Japanese have been playing with optimum frame flex over the past 15 years..where is the best place to engineneer this controled flex in?? Its very easy to change and control the constancy of a weld, this makes it a perfect place to do that surely??
And yea, it may make that weld in particlular weaker than the rest on the frame, but if it is designed to act as the 'hinge' then it would right??
Also, it would be unlikely the frame would snap behind the foward engine mounts, as it has the motor acting as a stressed member holding it together down to the rear mounts and swingarm pivot.

Welds are generally stiffer than the surrounding component, as they have more material, unless they have been ground flush. I've seen many an example where a weld has acted as a stiffener in a fabricated component. Pressure vessels are a good example. Nozzles in the pressure shell have to reinforced, both for strength and stiffness, if they are above a certain size. Such reinforcement can be from a welded collar, or even just a weld itself.

The motorcycle designers would engineer stiffness via the material and/or geometry of the frame and frame cross section - they would not play about with the welds - too variable.

Cheers,
FM

[Fooman]

Na, too many variables in a weld to accurately determine its elastic behaviour afterwards. I may be wrong, and I know the welding gear these days is GOOD... but I'd expect anything contributing to flex to be a longer member of the frame, cast/built with specific forms to add/control resistance to movement.

Flex on a joint is a "local". If riveted it works because the shaft of the rivet provide a point of rotation, albeit for incredible minor movement. A weld does not... at all (what was the class of ship in WWII that kept snaping after they introduced welded hulls in place of the riveted ones)?

That's where they learned that lesson.

To me the fact it snapped there says a couple of things
1) For the type of impact suffered, that weld was clearly the weakest point
2) the linear failure... down the middle of the weld, is unusual (to my eye anyway) and goes against what I learned of a weld being stronger than the bits it was attaching.

Perhaps it's a built in point of failure that prevents something more sinister happening? Who knows? I'd be surprised if that was the case. To me it looks like bog all penetration or (as someone else suggested) a boundary fusion issue caused by incompatible alloys refusing to fuse.

It's actually pretty easy to predict the elastic behaviour of a (good) weld - the modulus of the deposited weld metal doesn't change, and the geometry of the weld is fairly predictable, especially for automated and semi-automated welding

The Liberty ship failure (for it were they that snapped) wasn't about rigidity, but the toughness of the steel used to fabricate the hull - once the temperature got below a certain point (co-incidentally the same as the water temperature in the North Atlantic in winter), they became quite brittle. The fact that the ships were of welded construction meant that there was no edges to arrest the crack which formed from (minor) loading (literally - they cracked whilst been loaded at dock!) in the embrittled condition. A (properly) riveted join is not flexible at all, but the fact that there is a physical end to the material (the edge of the sheet) prevents crack propagation past a certain point.

This is why toughness/impact energy/K1C/ transition temperatures of a metal is an important factor in welded design/construction.

Cheers,
FM

[ManDownUnder]

It's actually pretty easy to predict the elastic behaviour of a (good) weld - the modulus of the deposited weld metal doesn't change, and the geometry of the weld is fairly predictable, especially for automated and semi-automated welding

The Liberty ship failure (for it were they that snapped) wasn't about rigidity, but the toughness of the steel used to fabricate the hull - once the temperature got below a certain point (co-incidentally the same as the water temperature in the North Atlantic in winter), they became quite brittle. The fact that the ships were of welded construction meant that there was no edges to arrest the crack which formed from (minor) loading (literally - they cracked whilst been loaded at dock!) in the embrittled condition. A (properly) riveted join is not flexible at all, but the fact that there is a physical end to the material (the edge of the sheet) prevents crack propagation past a certain point.

This is why toughness/impact energy/K1C/ transition temperatures of a metal is an important factor in welded design/construction.

Cheers,
FM

Cheers. A full (and quite interesting) writeup is here. I might have a rummage around that site... it may have some interesting potential.

MDU

[orangeback]

they arn't lasting long