Stelvio CARC failure in Oz AND South Africa

[sib]

Wow, I'm glad the bike was the only thing messed up. That's # two swing arm failure we have heard about, I'd say it's time for all carc owners to have a close look at there swing arms. Sure hope this doesn't turn into another flat tappet fiasco. Please let us know what Piaggio has to say about this.

No one ever died (to my knowledge) from the "flat tappet fiasco", but this seems really dangerous, much more so than the GM ignition switch problem.  And the statistics here also seem worrisome, it's not two out of 2 million, but two out of a few hundred (I don't really know what the production numbers are for CARC Guzzis, but the total is probably a lot less than 2 million).

[jacksonracingcomau]

Deja vu, all over again, looks identical to me
Oddest thing is they only break in Southern hemisphere, maybe cos we have dirt roads ?
Try Spanish speaking forums, next one will be in South America somewhere,
This bloke looks good tester, lovely pics
http://www.stelvio2stelvio.it/

[Moto]

It looks like the holes for the wiring leads were an afterthought. Probably a good analysis went into the design of the casting, without the holes, and then someone had the bright idea of drilling them later on in the design process. What a shame.

[Moto]

Deja vu, all over again, looks identical to me
Oddest thing is they only break in Southern hemisphere, maybe cos we have dirt roads ?
Try Spanish speaking forums, next one will be in South America somewhere,
This bloke looks good tester, lovely pics
http://www.stelvio2stelvio.it/

Wow! What photos! Guzzi should send this guy a spare swing arm to take with him, just in case.

[Demar]

No one ever died (to my knowledge) from the "flat tappet fiasco", but this seems really dangerous, much more so than the GM ignition switch problem.  And the statistics here also seem worrisome, it's not two out of 2 million, but two out of a few hundred (I don't really know what the production numbers are for CARC Guzzis, but the total is probably a lot less than 2 million).

This failure falls under the same category as the suspension link failure in 2012 on the Griso/Stelvio/Norge. Something to keep an eye on. If more fail I'd bet a recall will be implemented. It gives a chance to grease the splines.

[Triple Jim]

It looks like the holes for the wiring leads were an afterthought. Probably a good analysis went into the design of the casting, without the holes, and then someone had the bright idea of drilling them later on in the design process. What a shame.

If putting a couple small threaded holes in the casting results in failure, it was marginal to begin with.  I'm glad my old Tonti has a symmetrical steel swing arm and two shock absorbers.

[rtbickel]

I'm not a metallurgist but on photo #8 portions of that housing look porous.  It may just be the angle of the photo but it looks more like cheap pot metal than aluminum along the edge where it failed.

[Triple Jim]

You may be right, rtbickel, which would mean that the failure wasn't because of the added holes.  If something like a porous casting caused the failure, it would be likely that the crack would include all the stress risers, so it would be no surprise that it went through the hole.  Obviously it will take a lot of real analysis to solve this.  If this were my problem, I might start with breaking a dozen or so castings and see what I learn.

[Demar]

  If this were my problem, I might start with breaking a dozen or so castings and see what I learn.

Castings pose a unique difficulty for quality control. It's a process dependent upon a number of variables. Contamination of melt, improper heating/cooling, etc. That's why castings are usually designed with a large factor of safety. X-rays may be more useful than breaking but stressing to yield and breaking is certainly useful.

[Demar]

I'm not a metallurgist but on photo #8 portions of that housing look porous.  It may just be the angle of the photo but it looks more like cheap pot metal than aluminum along the edge where it failed.

I agree but it just might look like that due to the way it failed and not necessarily be the source of failure. It looks like the failure in the area around the tapped hole is a shear failure, like cutting. The area at about 2-o'clock and to the right, where it looks like pot metal, looks like a tensile failure like it was torn as the wheel folded under the bike. It could vey well be a bad casting, or a few bad castings. The trouble with castings is that they can look perfectly fine and be compromised internally.

[Trevor G]

If putting a couple small threaded holes in the casting results in failure, it was marginal to begin with.  I'm glad my old Tonti has a symmetrical steel swing arm and two shock absorbers.

I understand that aluminium will crack when holes have flash left around the edges. The edges of holes need to be smoorthly chamfered.

The earliest incident related to this is possibly the disastrous failure of pressure skins on the 50s De Havilland Comet Jetliners, which mysteriously fell out of the sky after some use.  After 6 months testing in an over-sized bath tub ;-) they found a crack appeared at a hole used for mounting a window frame, and traced the cause to the hole having not been cleaned around after drilling.

[John Warner]

Not quite.
The actual cause was the insufficient radii on the window corners (and other skin apertures).
That's why later Aircraft have much larger radii on the windows (and thicker sections around them), and on any other apertures.

A simple hole itself will not necessarily form a stress raiser, it's far more likely in this case to be the threads themselves that are the culprit.
Cut (Tapped) threads have fairly sharp troughs/valleys at their base, that's why the threads on critical (male) fasteners are Rolled, not cut, Spokes for instance, or high-performance Cylinder Head studs (and most Aircraft fasteners).

If there's nothing bolted to that hole, then it would be prudent to drill the threads out and chamfer and polish it, then crack-check it.
It would also help to 'cold-work' the hole, either by manual peening (small flap-wheel impregnated with small metal beads), or by drawing a smooth steel mandrel through the hole that's a thou' or so larger than the bore.

[azguzzirep]

The Guzzi dealer near me does most of the CARC repairs in Germany. (seals, etc)

I sent him the links to both discussions, so he can see the pics. I asked in the email, if he was aware of these failures.

I'll let you know his reply.

Tom

[pauldaytona]

So we have 3 known faliures now.

[Vasco DG]

Yup! Three documented failures in ten years of production. And seemingly all fairly close together in the manufacturing line.

Should it happen? No! Of course not. But obviously the gleeful doomsayers and haters of change will revel in yet another excuse to condemn anything made after 1957!

Pathetic.

[Randown]

Yup! Three documented failures in ten years of production. And seemingly all fairly close together in the manufacturing line.

Should it happen? No! Of course not. But obviously the gleeful doomsayers and haters of change will revel in yet another excuse to condemn anything made after 1957!

Pathetic.

I don't see any "gleeful doomsayers and haters" here. It's been a rational discussion until now.

[MotoZA]

Yes, thanks, please keep it rational.

[acogoff]

     My now retired brother was in the die casting game for 40 years so may have an idea as to the "problem".  I will show him these pictures when he comes deer hunting in a couple of weeks. Can't email pics to him as he  has no interneck as he moved away from it all at retirement, couldn't get away from the spouse though. To my untrained eye the crystalline structure of the aluminum looks a bit strange as to maybe the die was not up to temperature when they made the shot or contaminated metal mixture in the pot for a batch of swingarms. Have to wait and see what he thinks.

[Dean Rose]

Yup! Three documented failures in ten years of production. And seemingly all fairly close together in the manufacturing line.

Should it happen? No! Of course not. But obviously the gleeful doomsayers and haters of change will revel in yet another excuse to condemn anything made after 1957!

Pathetic.

Wonder how many were produced? Seems to be a very small percentage of reported failures so far. But maybe we can pin the production numbers down?
Don't have a dog in this fight but curious.

Dean

[oldbike54]

Wonder how many were produced? Seems to be a very small percentage of reported failures so far. But maybe we can pin the production numbers down?
Don't have a dog in this fight but curious.

Dean

 There's an idea  One does wonder if the bikes in question were actually being used as ADV tools , and not as purely street bikes . While the failure rate may be low , that type of catastrophic failure will send out alarms all across the motorcycle world . This would be a good time for Piaggio to step forward and deal with this before anymore similar incidents occur .

  Dusty

[MotoZA]

Mine was certainly used as an adventure bike, for me that's the whole point of having a bike like that. We literally have thousands of kilometres of gravel roads in South Africa just waiting to be explored. I was attracted to the Stelvio because of its gorgeous looks and the air cooled motor, and the drive shaft.

Where my bike broke down was between three small towns. If I was alone I would've had to walk 30 to 40 kms to the nearest farm house, not really an issue, but also not part of the original plan. Here's the location, for those interested:
https://goo.gl/maps/MTh2HkK2r9N2

I appreciate all the replies and will keep everyone posted, the bike will go to the local agents this week. I'm hoping Piaggio comes to the party.

[canuguzzi]

In my mind, the first failure was a fluke or abuse.  Now I see exactly the same failure on a different continent.  The only similarity I see is riding the bike off road and loaded.  You'd expect the swingarm to handle this since it's the same unit used in all the CARC bikes but now I wonder if Guzzi has exceeded the original design strength required.  After all, the CARC was first used in street bikes (Norge and Griso) and none of them failed.  Well, now I have something to add to my checklist when preparing for a long ride.  It's going to be hard to act smug around my BMW riding friends when they talk about rear drive failures.

Peter Y.

Short ride or long ride, does it really matter? The failure isn't going to care. 60 mph on a short trip is the same as 60 mph going cross country.

As quick check before each ride should go a long way to providing assurance. Only takes a few seconds. A small mirror might make it easier. Something to check each and every time though, like tire pressures.

[pauldaytona]

I think all were 2012 bikes? would be good to have VIN or engine numbers to see if they belong to the same batch/month in production

[WitchCityGuzzi]

I would bet this is a bad casting run. I have abused mine in all sorts of conditions. Rock crawling, bad and easy gravel, deep mud, ruts, etc, etc. No issues in 63,000 miles. Andrea Livio had no CARC failure on his round the world trip and that bike was heavily loaded and he rode some very gnarly roads/trails/paths/rivers. I doubt it's a design problem.

While it sucks if it happened to you, 3 failures in what is probably literally millions of miles on the CARC doesn't seem like time to pull the panic lever. Hopefully Piaggio can figure out if there was a bad run of the parts and address it like the link issue. 

[Dean Rose]

I think all were 2012 bikes? would be good to have VIN or engine numbers to see if they belong to the same batch/month in production

 :1:

Dean

[bad Chad]

Pete's right.  Thousands of carcs have been produced, and perhaps three have failed. 

If you want to fight windmills, that's your choice.

[oldbike54]

Pete's right.  Thousands of carcs have been produced, and perhaps three have failed. 

If you want fight windmills, that's your choice.

 The issue isn't about the thousands of carcs in service , but rather about the three Stelvios that have had a catastrophic failure. If you owned a 2012 model , which seems to be the problematic models , would you not be concerned and want something done ?

 Dusty
 

[Nick]

The issue isn't about the thousands of carcs in service , but rather about the three Stelvios that have had a catastrophic failure. If you owned a 2012 model , which seems to be the problematic models , would you not be concerned and want something done ?

 Dusty
 

:1:

[John Warner]

It looks like the holes for the wiring leads were an afterthought . . . and then someone had the bright idea of drilling them later on in the design process.

Not so.
There are little lugs cast into the Arm next to the holes, to prevent rotation of the Cable/Hose Clips themselves, so the mounting holes were planned from the off. 

[Bill Hagan]

Pete's right.  Thousands of carcs have been produced, and perhaps three have failed. 

If you want fight windmills, that's your choice.

The issue isn't about the thousands of carcs in service , but rather about the three Stelvios that have had a catastrophic failure. If you owned a 2012 model , which seems to be the problematic models , would you not be concerned and want something done ?

 Dusty
 

Actually, yes, Dear Leader Mod, I do see the statistical evidence of the successful many as outweighing the failure of a few, especially as the only persuasive failure to me seems to be the OP's.

And, as for "concerned and want something done," sure, but perhaps instead of gathering a howling mob with torches, pitchforks, and lynching in mind -- which this forum can become -- it might be more helpful simply to wait and see what if anything Piaggio does. 

But this is not, it seems to me, a Hobson's choice or one between Scylla and Charybdis.

As a guy who has had a failed oil pump seize the engine and CARC fail on my Norge, and with my Griso requiring out-of-my-pocket "rollerization," I am hardly a Piaggio party-line guy, as smitten as I am by Guzzis generally.  But I am willing to see what comes from sober study rather than wail about any of it now.

That said, I am not blowing this off ... yet.  I don't think it wrong to muse about it all, and I'll get under my Norge tomorrow with a strong light to see if there might be a crack.  If I had a Stelvio and wandered off the pavement -- or still lived in Atlanta, the Pothole Capital of the South -- I'd check more frequently.

Finally, seems to me that the OP is mature and has his head screwed on straight: "I appreciate all the replies and will keep everyone posted, the bike will go to the local agents this week. I'm hoping Piaggio comes to the party." 

Should be interesting.

Bill