Broken Torque Rod Bolt

[audiomick]

25 minutes ago, docc said:

. I wonder if Moto Guzzi superseded the part thusly . . .

That would be my guess.

25 minutes ago, docc said:

Do the later bolt heads (2003-onward) reveal a hardening level (i.e.: 10.9 or 12.9)?

Stein Dinse have a picture from a different angle to the one from Wendel. Seems to be a 10.9

https://www.stein-dinse.biz/product_info.php?products_id=4990#prettyPhoto

[docc]

Where are these bolts shearing @LowRyter, @kalev11 ?

At the head or at the thread/shaft interface?

 

[docc]

I am off the phone with Curtis at Harpermoto in the US (Missouri). He states the the later (hardened) bolt is available in NA and will make an order this afternoon. He confirmed the size is M10 x 1.5 x 59.  I have committed to six of them (to replace mine and share), and he will have four left on hand. $2.60US each + S/H.

He suggested putting together a kit which includes the lock nut (good idea to fit a fresh one) and the washer and spacer (most expensive part at $4.75US). I suggested we leave it at just the bolt and let folks decide what else to replace.

For example, his careful discussion led me to see that I have no "washer" and my "spacer" is on the bolt head side. [edit: this configuration is shown in the Parts Catalog for the "2nd Series" V11 Sport 1999-2001 with the 1.5 thread pitch bolt.]

Time to delivery is a hopeful 2+ weeks . . . (certainly in time for the sSSR in Kentucky).

A couple take-away from this important thread, so far: Do not neglect cleaning and greasing this critical pivot. And, perhaps the greater discovery: V11 before 2003 (likely including the 2003 "Carryover Sport") do not have a hardened fastener at this pivot and an upgrade to GU01357731 may be worth considering.

https://www.harpermoto.com/screw-10mmx59mm-01357731.html

[audiomick]

44 minutes ago, docc said:

... V11 before 2003 (likely including the 2003 "Carryover Sport") do not have a hardened fastener at this pivot...

Did Curtis confirm that then?

[Pressureangle]

I'm hesitant to jump in here but...

This bolt's job is not to hold your rod in shear. This bolt's job is to clamp the frame tabs onto the bushing spacer hard enough that it doesn't move at all, and the bolt should never be put in a meaningful shear state. Nobody has mentioned the torque spec for this bolt...
Secondarily, bolt hardness and tensile strength are not *necessarily* correlated with shear strength. Toughness is (which nobody quantifies on a bolt, it's a characteristic of the material of the bolt) If the bolt doesn't clamp sufficiently, and is tough enough that it never shears, you'll eventually end up with egg-shaped holes in the frame tabs as the weakest link wears. All that said, a harder bolt with higher tensile strength is less subject to relaxing over time and allowing the spacer to bang it every time you roll on/off the throttle. 
Meh.

[audiomick]

5 minutes ago, Pressureangle said:

... Nobody has mentioned the torque spec for this bolt...

That can be derived from the number, can't it?

The one I linked at Stein Dinse is apparently a 10.9

According to this table (which includes values that I know from other applications, so I guess it is accurate...)

an M10 10.9 can be tightened up to 70 Nm.

https://www.anzugsmoment.de/anzugsmoment/

the tensile strength can be derived from the formula shown here in the diagramm under the title "Festigkeitsklassen von Schrauben".

https://www.rosentaler-schrauben.de/magazin/schrauben-festigkeitsklassen/

The first number 10 * 100 N/mm² = 1000 N/mm² stretch before it breaks

The first number times the second number 10 * 9 * 10 N/mm² = 900 N/mm² stretch before it is permanently deformed.

 

Or did you mean something else?

 

[Joe]

12 minutes ago, audiomick said:

That can be derived from the number, can't it?

The one I linked at Stein Dinse is apparently a 10.9

According to this table (which includes values that I know from other applications, so I guess it is accurate...)

an M10 10.9 can be tightened up to 70 Nm.

https://www.anzugsmoment.de/anzugsmoment/

the tensile strength can be derived from the formula shown here in the diagramm under the title "Festigkeitsklassen von Schrauben".

https://www.rosentaler-schrauben.de/magazin/schrauben-festigkeitsklassen/

The first number 10 * 100 N/mm² = 1000 N/mm² stretch before it breaks

The first number times the second number 10 * 9 * 10 N/mm² = 900 N/mm² stretch before it is permanently deformed.

 

Or did you mean something else?

 

 

[LowRyter]

4 hours ago, docc said:

Where are these bolts shearing @LowRyter, @kalev11 ?

At the head or at the thread/shaft interface?

 

dunno, the bike's still in the shop awaiting a mirror and other stuff.  I briefly saw the bike but didn't ask for the old bolt or think to ask him.

[LowRyter]

3 hours ago, docc said:

I am off the phone with Curtis at Harpermoto in the US (Missouri). He states the the later (hardened) bolt is available in NA and will make an order this afternoon. He confirmed the size is M10 x 1.5 x 59.  I have committed to six of them (to replace mine and share), and he will have four left on hand. $2.60US each + S/H.

He suggested putting together a kit which includes the lock nut (good idea to fit a fresh one) and the washer and spacer (most expensive part at $4.75US). I suggested we leave it at just the bolt and let folks decide what else to replace.

For example, his careful discussion led me to see that I have no "washer" and my "spacer" has been moved to the bolt head side at some point in mySport's nefarious history.

Time to delivery is a hopeful 2+ weeks . . . (certainly in time for the sSSR in Kentucky).

A couple take-away from this important thread, so far: Do not neglect cleaning and greasing this critical pivot. And, perhaps the greater discovery: V11 before 2003 (likely including the 2003 "Carryover Sport") do not have a hardened fastener at this pivot and an upgrade to GU01357731 is highly recommended.

https://www.harpermoto.com/screw-10mmx59mm-01357731.html

Wait, did I read right that you have a sheared bolt too?  Or are you getting a replacement as preventative maintenance? 

So far as getting a replacement for mine, Don was saying something about obtaining  it when he phoned me about it but I really didn't pay that much attention.  I do know he said he was getting the stronger one.  I think he got one in town rather.    (IIRC when I went through this on my Duc that the stronger metal is also more brittle.)   

 

We need Chuck or Huzo to get to the bottom of this!

 

BTW- we've been all over Curtis, MG and AF1 just trying to get the fuel level sender for my EV.  None to be found.  Looks I'll plug the tank in the meantime.  Both Guzzi grounded.

[docc]

4 hours ago, audiomick said:

Did Curtis confirm that then?

"... V11 before 2003 (likely including the 2003 "Carryover Sport") do not have a hardened fastener at this pivot..."

No. I am basing that on it having been stated the part number changed in 2003 and the fact that my early bolt has no headstamp and the replacement does (10.9). Along with the fact the original bolt configuration is NLA from Moto Guzzi (superseded?).

AFAIK, there is no torque specification for this fastener in the Guzzi chassis. It is fastened with a lock nut ("NyLoc" type). Whether or not the bushing is intended to be "clamped" has been the subject of debate. I question whether this fastener could suffer from being unnecessarily overtorqued, leading to failure (especially the earlier, unrated, fastener).

Also, whether the two fastener failures we have in question are actually best described as "shear" failures. Technically speaking, probably not.  This is why I am asking both @LowRyter and @kalev11 to clarify the more exact description of their failures.  Both of these examples are 2001 models.

Finally, @LowRyter, to clarify: I have no failure, only replacing pre-emptively with what appears (to me) to be a superseded part. Learning from other's experience. Thanks for posting this!

[Pressureangle]

3 hours ago, audiomick said:

That can be derived from the number, can't it?
Or did you mean something else?

 

Yes of course the specs are easy to know, but I meant that nobody has said they either checked it (but docc's wheel off checklist) or verified that it was tight to spec. ...aaaand you may ask if I applied a torque wrench to my own. I have not. But I have given it the ol' grunt test from time to time. 

This particular mechanism of failure is pretty universal in any device that has connecting rods or stay arms with a captive bushing. 

[leroysch]

7 hours ago, LowRyter said:

I go to Ace most of the time.  Seems to be better than Fastenall.  We have industrial fastener supply on the southside of the City in a little town with all the strip clubs.  Minimum purchase is like $20 there. 

Anyway, I played all those hardness grades with a non load bearing bolt assembling my Duc's pannier bracket that sheared.  The new (stronger) one sheared just as the other one.  According to the forum, the better fix was to tap it out and go to a larger size.  Anyway, I'll see if the works.  I'm planning to ride the Duc to MotoGP Austin.  Full confession, I did have my bags overloaded according to Ducati.  It's actually a Givi designed system with a Ducati badge. 

Is there a cover charge too?

[audiomick]

5 minutes ago, Pressureangle said:

... I meant that nobody has said they either checked it (but docc's wheel off checklist) or verified that it was tight to spec. ...

Yes, that occurred to me after I posted. Good point.

 

[al_roethlisberger]

I love(d) Fastenal, even just to browse around, but especially as a local source to buy (often in stock) or order fasteners.

 

However our local Fastenal store switched to direct business supply only sometime over the last few years, so no more walk-in public customers 

 

For me to buy anything now I'd have to have a business account, and I suspect a minimum order.

[docc]

5 hours ago, Pressureangle said:

I'm hesitant to jump in here but...
This bolt's job is not to hold your rod in shear. This bolt's job is to clamp the frame tabs onto the bushing spacer hard enough that it doesn't move at all, and the bolt should never be put in a meaningful shear state. Nobody has mentioned the torque spec for this bolt...
Secondarily, bolt hardness and tensile strength are not *necessarily* correlated with shear strength. Toughness is (which nobody quantifies on a bolt, it's a characteristic of the material of the bolt) If the bolt doesn't clamp sufficiently, and is tough enough that it never shears, you'll eventually end up with egg-shaped holes in the frame tabs as the weakest link wears. All that said, a harder bolt with higher tensile strength is less subject to relaxing over time and allowing the spacer to bang it every time you roll on/off the throttle. 
Meh.

"Egg-shaped holes in the frame tabs " are a compelling reason to see that the bushing is clamped by the frame tabs through the force of the bolt.  Another trip through the Workshop Manual and I do not see the torque reaction rod depicted except where it is being disconnected from the reardrive. I do not see it mentioned anywhere else, especially in relation to the frame connection. Am I missing it somewhere?

The general torque value page states that M10x1.5 is tightened 45-50 Nm (with no reference as to hardness ratings).