2009 Stelvio. Cracked Fork/Axle Pinch Bolt Damage. Help Please.

[rodekyll]

[snippity]

By the way, I wouldn't downrate anyone for over tightening these pinch bolts. I can understand someone thinking they needed to torque them down good and the casting doesn't look vulnerable upon casual observation.  Of course, a dealer shop should have been knowledgeable of the peculiarities of these bikes but ... whatever.   Things happen.

[snip]

The pinch bolt has been a staple of mechanical stuff since the goddess was a puppy.  I'd downrate the ratsnot out of a 'mechanic' who broke $1000 worth of parts due to mishandling pinch bolts.  I'd show him a whole new use for a torque wrench.

[catneck]

3 dealers are not aware of fixes other than: "Buy new copies of same (potentially error prone) design and hope Mongo is able to read 7 ft/lbs on his torque wrench".
They are all aware of the issue, I am just the latest to call on it.
Frustrating.
Its why I keep records on my bikes-to prove accountability in these situations.
Wish the PO had.
Now back to looking for the used needle in the haystack.

[oldbike54]

Ducati aluminum swingarms cracked and were weld repaired routinely. Steel frames cracked and were scrapped routinely..

YMMV
Best,
Peter

 Aluminum swing arms are usually an extrusion , different from a basic casting .

  Dusty

[Curtis Harper]

During previous episodes with the same parts I have talked with Marzocchi as well as Guzzi. Marzocchi denies any existence of a problem saying that the proper torques are supplied to the manufacture. This is not a Guzzi specific problem, it's an education problem. Anything pinch bolt like this can break from a ham-fisted mechanic. I don't know how many brembo master cylinders I have seen snapped for the came reason. If this was done at a shop, I would expect them to stand behind their work. Just as anyone would expect me to fix something I broke.

What I can tell you is this. If the part is available currently from Piaggio, probably better get your hands on it before it is no longer available. 

[Peter from Sch'dy]

Aluminum swing arms are usually an extrusion , different from a basic casting .

  Dusty

Oh, I don't know..perhaps..but I wouldn't weld this failure anyway. Unless there was no other way.

Best,
Peter

[oldbike54]

Oh, I don't know..perhaps..but I wouldn't weld this failure anyway. Unless there was no other way.

Best,
Peter

 "Usually" as in almost always  It is odd that steel Duc frames are scrapped , might have to do with all of those little tubes going every which direction 

  Dusty

[Vasco DG]

This fork bottom looked close to having the same bracketry as the NTX fork.   Just a thought.  It's a Duc part, but more importantly, it's a Marzocchi part.  This might be another avenue for bottoms.  You would have to verify tube diameter and axle diameter of course.

http://www.ebay.com/itm/Ducati-Monster-1100-EVO-Marzocchi-Right-Side-Lower-Fork-Leg-Foot-Caliper-Mount-/271313974794?hash=item3f2b92b60a&vxp=mtr




Price:
US $168.74
Buy It Now

Unfortunately a completely different component. The Stelvio forks use a leading axle and it is this that makes the break so critical. The forces acting on the axle as well as pushing upwards will be using the bolts themselves as a fulcrum which in the right circumstances may snap off the lower part of the casting and simply allow the wheel and axle to fall out of the fork. The integrity of the casting is a vital safety issue and I'm sorry, I don't care if someone rode back from Russia with a bolt through tha axle and casting the fact remains that the potential for serious injury or death in the event of failure is astronomical.

Even if you are willing to take that risk yourself at least have the decency to consider others. A quarter of a tonne of cartwheeling Stelvio could cause a lot of damage to innocent bystanders. Consider that.

Pete

[John in PA]

What is the factory torque spec on the bolts in question?  And, is that trustworthy, and technique-dependent (Re:Lannis' post about tightening and re-tightening two fasteners working in parallel)

[catneck]

10 NM or 7.3 Ft Lbs..
Not much is required.
Per earlier post, do not recheck after first is torqued.

[Captainjos]

one thought re possibility of welding; the American Welding Society (aws.org) has multiple forums with professional advise. Maybe post your issue there and let the professionals look at it.

[Lannis]

10 NM or 7.3 Ft Lbs..
Not much is required.
Per earlier post, do not recheck after first is torqued.

I'm trying to be quiet after my first post, but THIS is correct.   

The implication has been that if you simply read the right numbers off the torque wrench, and keep tightening both until you read 7.3 lb-ft on both, then all is well, so simple ANYONE can do it.

In fact, you will be looking at a broken clamp if you do that.   So maybe someone can take a little video of exactly how you use a torque wrench to tighten down TWO parallel bolts on a clamp to a given torque, so Mongo see how him do, and Mongo do like Sheriff Bart?   DO expert mechanics have a technique (as John asked) that involves something more than simply listening to a wrench click?

Lannis

[Mike Tashjian]

That fork is a bad design.  There is no way that should ever been produced by a reputable manufacturer period.  In every instance the bolts should be able to strip the aluminum threads out of the tube first before breaking the clamp area.  Inch pounds or ft lb's(pound ft too) should not be able to break a part designed well.  And really this is the part holding the front wheel on. Just call that that fork what it really is, a poor design that should not have ever made it to production.  Mike

[Lannis]

That fork is a bad design.  There is no way that should ever been produced by a reputable manufacturer period.  In every instance the bolts should be able to strip the aluminum threads out of the tube first before breaking the clamp area.  Inch pounds or ft lb's(pound ft too) should not be able to break a part designed well.  And really this is the part holding the front wheel on. Just call that that fork what it really is, a poor design that should not have ever made it to production.  Mike

Yeah, we're kind of saying that about the manufacturing processes and design for the mirrors, and the spark plug boots, and the valve train, and the swingarm bearings, and the relay-less headlights, and now the front-end clamps ...

Maybe there's a trend here, I don't know ....

Lannis

[grebmrof]

And really this is the part holding the front wheel on.

I guess I look at axle clamps like that as one that holds the axle in place so that the nut on the end of the axle can be tightened properly and then the clamp on that side of the axle can then be tightened down properly.  But herculean tightening of either clamp is not needed.  With a double bolted clamp, I would think that one would first finger tighten and then slowly tighten each in very gradual steps, alternating to one bolt and then to the other, slowly...anyone have thoughts on this?  Looking at this part, I think I sure could have designed a more robust piece than that, but what do I know, sigh...

[Peter from Sch'dy]

If I owned an undamaged unit, I'd be tempted to shim the pinch slot. the desired pinch could be calculated by measuring the pinch gap both tight and loose as well as od of axle and id of fork. shim size would ideally allow for desired pinch at the specified torque. Some forks seem to be susceptible to this. On the Norge I use a torque wrench. shrug

Best,
Peter

[Vasco DG]

That fork is a bad design.  There is no way that should ever been produced by a reputable manufacturer period.  In every instance the bolts should be able to strip the aluminum threads out of the tube first before breaking the clamp area.  Inch pounds or ft lb's(pound ft too) should not be able to break a part designed well.  And really this is the part holding the front wheel on. Just call that that fork what it really is, a poor design that should not have ever made it to production.  Mike

S'funny, a while back there was another thread about Marzocchi ceasing production and I mentioned in passing that I thought that it had been a long time since they had been much chop and I got jumped on. 

Pete

[pauldaytona]

the design with the axle in front of the legs is normal with all enduro bikes. I couldn't find one using the same forks as the stelvio. So if it isn't available at all, or the newer forks, with new triple clamps, or custom made triple clamps and (used)forks of another adv bike with axle under the legs

[catneck]

Found a couple shops that may be able to find used parts.
Glad this is not my only bike!

[jdgretz]

You might check with J & S East Valley Garage, 1610 E Valley Rd., Santa Barbara, CA 93108 (805) 969-4147.

He does some amazing things with aluminum engine blocks and may be able to do something with these. Might be worth a phone call.

jdg

[Chuck in Indiana]

That said , Chuckie hasn't weighed in yet , and he probably knows more than most about this . Yo Chuck , any ideas ?

Yeah, but none of them are good. First.. as Lannis sez, that two pinch bolt thing isn't a good idea. Very little torque is required and it is way too easy to over torque them.
Many will flame me, but I *think* it could be welded. The problem being finding a source that is capable of doing do it. Back in the day, I knew a guy that could do it, had the normalizing ovens, etc. but he died of brain cancer like most of the others. 

[Vasco DG]

Chuck, in a world where putting the right amount of gear oil in a gearbox and balancing throttle bodies on a system as simple as the W5AM is a seeming anaethma would you recommend taking such a structurally vital component to your neigborhood welder?

Yes, I'm sure that with the correct tooling and skills, probably at a price far in excess of new parts, it could be done. Most things can! But is it logical or the best course of action???

Pete

[Chuck in Indiana]

Chuck, in a world where putting the right amount of gear oil in a gearbox and balancing throttle bodies on a system as simple as the W5AM is a seeming anaethma would you recommend taking such a structurally vital component to your neigborhood welder?

Yes, I'm sure that with the correct tooling and skills, probably at a price far in excess of new parts, it could be done. Most things can! But is it logical or the best course of action???

Pete

It's probably not practical, I'll give you that. From memory, here's what needs to be done. Machine the crack completely down to base metal with a ball nose end mill. Taper that back on roughly a 45 degree angle on both sides. The welder will preheat the whole piece in an oven.. sorry.. I don't remember at what temperature. When it is heat soaked, he'll fill the machined out area. Once welded, he'd cover the whole thing in a box of mica and put it in another oven to cool slowly.
Now, of course, the area including the pinch bolt counterbores will have to be machined back on location. That is a pretty good trick in itself..  but doable on unobtainium stuff.

[catneck]

Used part search has been fruitless.
I also am coming to grips that the brand has less than stellar spares inventory.
I am coming over from another European marque.
I have been spoiled by that brand's attention to customer issues.
This would have been covered. Forever.
And a workaround would be engineered from available spares.
I wish I didn't like this goofy bike.
It would be much easier that way.
Rant over.
Back to parts hunting.

[Vasco DG]

I know of a bloke over here who is wrecking out an early Stelvio but given the discrepancy in parts prices between here and where you are it would probably be cheaper just to buy new.

Pete

[Silver Goose]

I have a question to all that would care to comment.

With the proper torque setting, the clamp gap is set. Let us say for this question that the gap is .100 of an inch,( for the folks on the wrong standard),approx 4mm. What if a shim was placed in the gap before the bolts are tightened. Now apply the correct torque, if Meathead the Strong twist the bolts a little tighter, the gap has hit it's limit. To further limit the chance of a problem drill the shim plate so that the pinch bolts will go though and hold the plate. I suggest this out of fear. I did this for my Stelvio, albeit I am the only one that changes the wheels it has given me some level of peace.

If it works for you great, if not throw it on the pile of bad ideas.

Good luck

[Peter from Sch'dy]

If I owned an undamaged unit, I'd be tempted to shim the pinch slot. the desired pinch could be calculated by measuring the pinch gap both tight and loose as well as od of axle and id of fork. shim size would ideally allow for desired pinch at the specified torque. Some forks seem to be susceptible to this. On the Norge I use a torque wrench. shrug

Best,
Peter

[canuguzzi]

Pinch clamps for the Honda ST 1100 handlebars are notorious for cracking until it was discovered that once loosened they are tightened in a sequence different than what seemed obvious. Using a torque wrench only assured that if the sequence of tightening wasn't correct, the clamps broke just as easily.

The pinch bolts worked on uneven gaps, trying to make them even only resulted in cracking. Many owners therefore tightened them by feel but rarely put the handlebars on properly once removed.

Maybe the pinch bolts on the Stelvio work the same way?  On the ST, if memory serves, there was only a gap on one side, the other being set down in contact and then the other set to the proper gap.

[mphcycles]

this probelm, while not common is not unheard of. I would never weld it. its cast pot metal. The one case I heard of was torqued by Larry with a digital snapon 1/4 drive wrench. The boy is meticulous about torquing fasteners. The bike we touched broke the clamp 1500 miles later in Canada.
I would source a later fork assembly if pointed emails to customer service didnt get you reults

[catneck]

Later assembly would be optimum.
I dont know what would fit.
Dealer told me these were 1 year only.
Later units were bigger diameter tubes, and he has seen those crack as well.
Edit: I stand corrected. Smaller tubes. Do they also crack?

[Vasco DG]

Later models use 45mm rather than 50mm legs.

Pete