Stelvio CARC failure in Oz AND South Africa

[Vasco DG]

Oh good grief!

No, you won't. You know why? Because I've worked with the wretched CARC system since its inception and I've NEVER seen a problem! With the linkages? There were probably at most four that got on bikes as a result of some nong not cutting the end off the extruded bar. The factory issued a recall foe ALL bikes from that batch.

I'm sorry you broke your motorbike but embarking on an ill informed campaign to query build quality is just a wee bit pathetic. Sorry, you won't 'Convince' me because there is nothing to convince me of. If I experience a problem I will alanlyse it and make a decision not based on the shoutings of some hysteric whose first post on a board is a broad brush claim that the product is flawed based on a sample of one.

Pete

[beetle]

well nothing is perfect and just like the suspension link there is always a few that dont make the grade! Too bad I cant post all the findings I think it would change your mind about the quality!

Oh please post your findings. Pretty please. Why can't you? Please do post them. Please!

[Vasco DG]

You have to understand Mark. To get a return to safety and good engineering we need to return to 23 inch front wheels and mild steel tube girder forks with cast iron forging so for the linkages. Couple this with crowded ball cup and cone steering head bearings with no oil seals and a diamond, single downtube, cradle frame with a rigid rear end, (No chance of a breakage there with a 20 inch rear wheel with Dunlop Pneumatics' on it! Although perhaps wiring them on to the rims would be better! No Siree!) suspension at the back? That's what a sprung saddle is for!

Heavens to Betsy man! Get a grip! You'll be trying to tell us that the days of carbide lighting, bulb horns and exposed valvegear are numbered next!

[Offcamber1]

I read through this entire thread and besides the stellar entertainment value provided by Pete and Martin, my only thought was that while the part in question might well be of sufficient strength in its original application on the Breva 1100, Griso, and Norge, it might be just a tad on the marginal side for use on the Stelvio.  Many engineering factors to consider in that equation...

Having spent most of my life fiddling with production based components in racing applications, I can think of numerous examples where seemingly over-engineered parts were stressed in ways that they were totally unintended for; the consequence was usually castrophic (read: $$$$$$) failure.  Similarly, the harmonics associated with riding a Stelvio fairly regularly on unpaved roads might well cause the occasional marginal swing arm casting to fail at a stress point that might not ever fail had the same casting been mounted on a Griso that rarely, if ever, left the pavement.

Disclaimer: I am not an engineer.

Ciao,

Kip

[Vasco DG]

Kip, if there was an endemic problems they'd be snapping like dry twigs over here. There are lots of blokes doing high miles on badly corrugated dirt and so far the one alleged failure happened at low miles on a city bike.

Sorry, the numbers aren't there and the stories don't stack up. Who knows what happened to the ones that failed? Someone could of jacked the bike up under the swingarm stressing it in a way it wasn't supposed to be stressed. Who knows? I'm still saying that it's a sound system but like any component it can be damaged by abuse.

[ITSec]

I haven't zoomed in on the picture, but it looks to me like the crack was there for a while. Dark colour in front of the tire , and shiny ( fresh ) aluminium colour where it finally let go.
Giving it a bath once in a while , that crack may have been discovered before it failed completely, Ohhhh thats right , some of you guys are allergic to a clean bike  :D
-Ron.

Hey, mine gets washed - every time it rains, here in Las Vegas!

[oldbike54]

 Pete and Mark , I respect both of you greatly , but if this happened to me I would not be happy . Sorry to be the fly in the ointment , but maybe their is a legitimate cause for concern here .

  Dusty

[Offcamber1]

Someone could of jacked the bike up under the swingarm stressing it in a way it wasn't supposed to be stressed. Who knows? I'm still saying that it's a sound system but like any component it can be damaged by abuse.

Ed Zachary my point, and I am in total agreement with you on that as an outstanding example of a component being used in a way in which it was not intended.  I was thinking more along the lines of damaging harmonics from constant high frequency inputs, but we're on the same tack here.  Your's is admittedly a better and far more likely scenario.

Speaking of under-engineered...  I might just fire up the Lario and take it for a ride tomorrow!

[beetle]

Pete and Mark , I respect both of you greatly , but if this happened to me I would not be happy . Sorry to be the fly in the ointment , but maybe their is a legitimate cause for concern here .

No need to apologize. It is a cause for concern. The question is, exactly how much of a concern? The CARC has been around since 2005. How many units have been sold? How many have had a catastrophic failure? I don't mean bearing failures or leaks, but where the swingarm has broken that wasn't due to impact damage or negligence on behalf of the rider?

There's a lot of conjecture in this thread, and yes I'm guilty of it too, but there's been no data presented to compel me to believe this failure occurred randomly. Someone posted that they had data but couldn't post it? Why not? If someone posts something on the net without data to back their claim, I call BS.

[Triple Jim]

sorry Im havind trouble loading a photo attachment - is there a secret button hiding somewhere??

A thread about how to post photos is at the top of the FAQ section of the board:  http://wildguzzi.com/forum/index.php?topic=16183.0

[Bobolink]

If the swing arm supports the wheel from one side, and it broke under the rider's and its own weight,  why is the tire tipped and turned the way it is?   Shouldn't  the gearbox side be down?  Wouldn't such an accident try to pull the unit apart?  The unit looks compressed. It sort of looks more like impact damage to me.  YMMV

[MotoZA]

Hi, this is my first post and unfortunately I'm the bearer of some bad news. My Stelvio's swing-arm failed catastrophically last weekend while on a trip through the Ceres Karoo in the Northen Cape in South Africa. Photo's here: http://1drv.ms/1MvnBO1

The incident took place on Friday the 9th of October 2015. The CARC swing-arm broke in half and damaged quite a few parts of the bike's rear (the rim and tyre is however still perfect). The front suspension saw the same road surface/conditions and nothing happened. I'm still at a loss of why the swing-arm simply broke like this (at that moment I thought the rear locked up for some weird reason, until the bike came to a standstill and I was faced with the horror and utter shock of a broken swing-arm). I actually said WTF aloud and then for a moment thought I was dreaming. Honestly, it was surreal. I managed to keep the bike upright during the break and didn't drop it because I was going slowly (about 40 kph, max 50 kph, I was in third gear) and the road conditions were flat. I've been riding bikes for 20+ years, so that probably also helps.

There is one other very similar case I found on this forum: http://wildguzzi.com/forum/index.php?topic=75525.0. Same year bike, similar mileage, was traveling at a similar speed, similar conditions, etc., from what I can learn from the post in any case.

I've been on much worse gravel roads, fully loaded with a pillion, with my old GS 1150 and never had issues like this, also on the weekend there were 5 other bikes that did the same route and their bikes didn't break, we were nowhere close to pushing the bikes to their limits nor abusing them. All my vehicles are in excellent condition, I look after my stuff (notice the duct tape on pillion grab bars and the little carrier behind the rear seat?, so that they don't get scratched when I strap my luggage on). The fact that we could recover the bike with a 2-wheel drive pick-up (without diff-lock) also says that the road conditions are normal for a gravel road.

It is my opinion that the tapped hole in the swing-arm acts as a stress raiser (stress concentration). There is no reinforcing or thickening of the aluminium casting where the tapped hole is, I find this surprising.

I'd therefore like to, or need to, warn other Stelvio/Griso/Norge riders of the potential of the swing-arm breaking like this! Please check underneath your bikes in the area of the tapped hole closest to the rear damper (there are two, used for clamps for the brake line and ABS sensor wire -- see photos below) to see if there are any cracks, you could potentially avoid this from happening to you. I was lucky because I was going slowly, but if this happens at speed and/or with a pillion and luggage on the back, people can get seriously injured or worse... Imagine hitting a pot-hole (which is MUCH worse than the shallow gravel dip I drove through) at 120 km/h on a public road with other cars, etc.

The Stelvio should be able to handle gravel roads and the dips and washouts that come with them without any issue. I'm hoping this is a case of bad aluminium casting.

I was originally going to claim from my insurance, but this is first and foremost a mechanical failure, and one that needs to be addressed and/or looked into. The swing-arm design might be fine for tarred road conditions, but with the extra weight of the Stelvio plus luggage and the more severe demands of gravel roads it might be pushing the design beyond it's limits. Of course I'm assuming a lot here, still, that tapped hole in a highly stressed area bothers me...

I'm returning the bike and swing-arm to the local agents in South Africa so that they can hopefully send the swing-arm to Italy for analysis. I'm hoping for a responsible response from Piaggio and I'm going to be seriously dissapointed if they claim it's abuse, because it's not.

Worst of all is the looks of pity I got from the guys who were on the trip with me, guys on BMWs, KTMs and one guy on a Honda. Not nice.

Safe riding.

Regards,
MotoZA

[elvisboy77]

Wow!  Glad you are okay.  I think you are right about the hole being the culprit.  I hope you get it repaired, and I hope this doesn't happen to anyone else!

[oldbike54]

 Yes , REALLY glad you are alright . Keep us apprised .

  Dusty

[Scud]

Thanks for posting this incident and for an objective analysis of the failure. I've been toying with the idea of getting a Stelvio, and I tend to ride solo on much rougher terrain than in your picture - with tools and supplies. But no amount of Quicksteel is going to fix a broken swingarm.

What goes into that tapped hole? It seems from your pictures that anyone concerned about it could have a thick bead welded around the inside of the swingarm - and then have the threads tapped in further. That wouldn't interfere with the driveshaft, right? If it did, you could weld the bead on the outside - it just wouldn't be very attractive.

Keep us posted on the responses from Moto Guzzi.

I felt your shame from the BMW riders' reactions. Anytime something goes wrong with my Husqvarna, I feel similarly from the Orange crew (KTM). 

[MotoZA]

I don't know what goes into that hole, if someone can take a photo of the underside of the swing arm it would help. EDIT: It's for a plastic clip to route the brake line and ABS sensor wire.

There's no extra material/metal in that area for a hole, as would normally be the case.

The Oz failure also cracked through the hole, according to the post.

I wouldn't weld the aluminium casting since there's a good chance you may change the material properties due to the heat input.

[Arizona Wayne]

Maybe that's a drain hole for anything that might collect in there like water, oil, etc.

[italianmotor]

Incredible, glad you're fine. More's the shame as the Stelvio is a great bike to ride. Hope Piaggio come back to you with some sensible ideas.

[MotoZA]

No, I don't think that's a drain hole. The things that can leak into the swing arm cavity is oil from the final drive and from the gearbox. Even so, why tap the hole with thread? Thanks for the thought.

My wife asked me how I feel about the bike now, and I replied that it feels as though a girlfriend broke up with me (when I still dated, of course). "Betrayed?", she asked. "Yes, betrayed." 

[Wayne Orwig]

From the photos, it looks like there may have been a crack for a while near the hole. Then the rest of the break looks fresh. Would you agree with that?


Looks like something to keep a close eye on at tire changes at least.

[Triple Jim]

From the photos, it looks like there may have been a crack for a while near the hole. Then the rest of the break looks fresh.

The whole bottom part that the hole is in looks darker than all the rest.  If that part was really cracked for a while it may well have been visible from the outside.

[Wayne Orwig]

The whole bottom part that the hole is in looks darker than all the rest.

That is what I see.

[Randown]

Well it is placarded "CARC", Careful Across Rough Country - you should have known. 

[MotoZA]

CARC acronym, I didn't know

Yes, I agree that it looks like an old crack, it's got the signs of a classic fatigue failure. No doubt helped by the tapped hole, which is in essence, a crack. We all know how toilet paper works, same principle...

Why put a hole in a part of the bike that sees variable tension combined with variable torsion? One could argue that one should check the swing arm for fatigue every now and again, but where do you draw the line? The frame and many other parts of the bike see the same number of fluctuating loads, maybe not the same in magnitude, but fatigue is a design concern and can be designed for, and should. It's fairly simple stuff you do in your 3rd year of studying mechanical engineering.

The whole point of getting shaft drive is the fact that it's maintenance free, I don't want to crawl underneath my bike to look for cracks. I don't do it with my cars. It's ludicrous to expect owners to do that.

Having said that, I do however suggest that Stelvio riders have a look at their swing-arms regularly, at the front tapped hole.

[Green1000S]

The hole?

Theres TWO of them. A plastic tab is pushed (or screwed) into the hole and it holds the brake line and ABS sensor wire.

Here's few shots of 2014 Stelvio NTX.

[Triple Jim]

One could argue that one should check the swing arm for fatigue every now and again...

It's hard to check for fatigue that's about to cause a crack.  You're pretty much limited to checking for an actual crack.     

[pyoungbl]

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.

[56Pan]

It's hard to check for fatigue that's about to cause a crack.  You're pretty much limited to checking for an actual crack.     

For fatigue that's about to_cause_a crack, I agree.  But these kits will find cracks that you can't see in most cases:
http://www.grainger.com/product/SPOTCHECK-Penetrant-3WU63?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/3NE71_AS01?$smthumb$

I've used them and they work.

[Triple Jim]

I suppose you'd have to take all the paint off the aluminum to use that.

[lucian]

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.