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Discussion Starter #1
When trying to tightening the rizoma headlight fairing bracket to the top tripple/steering head clamp bolt up to 20Nm ( rizoma specified 20-22Nm)... boom! part of clamp inner thread just failed (see photo). Only small part of the thread seems to fail.
Loosen out back the bolt and retightened up to around 18Nm. Question: is it safe for me to ride in this condition? Or should i consider tapping back the thread or completely change the top tripple?
 

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When trying to tightening the rizoma headlight fairing bracket to the top tripple/steering head clamp bolt up to 20Nm ( rizoma specified 20-22Nm)... boom! part of clamp inner thread just failed (see photo). Only small part of the thread seems to fail.
Loosen out back the bolt and retightened up to around 18Nm. Question: is it safe for me to ride in this condition? Or should i consider tapping back the thread or completely change the top tripple?
Seems like the bolt is too short, the bolt needs to longer by at least as much as the new component is thick.
 

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Discussion Starter #8
Bolt long enough?
My thought as well Max. Im using the bolt supplied by Rizoma which around 1” longer but their spacer and bracket is thicker than that. But this part from Rizoma is been a while in the market already and i didnt find any complaint around
 

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Im using the bolt supplied by Rizoma which around 1” longer but their spacer and bracket is thicker than that. But this part from Rizoma is been a while in the market already and i didnt find any complaint around
Maybe they accidentally added the wrong bolts or spacers (or you mixed something up?).

The fact that the spacer and bracket are thicker than the added length should have been a warning. :confusion:
 

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Typically yes, however in your case it can become complicated. You can't get to the threads as the pinching part is right in front of it. Drilling the hole to get the insert in place may make the hole in front of if too large.(Hui can you help here? I think you understand me best, but my English is lacking)

In your situation you may want to check how much thread is still left in the top yoke and if the majority is still there, use a taller bolt that goes all the way through.... But that's hard to judge from a distance

Odds are you want to take the yoke off and have a fabricator look at it.
 

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Discussion Starter #14
I understand as you mean the threaded part is only on the back side of the 2 pcs clamp while the front side is only the straight hole. Indeed its quite hard to judge what’s left on the thread. Probably try to measure it with vernier caliper and minus the failed piece that i had in hand.
Would check with my dealer too.
 

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Adding a Helicoil is safe and standard practice in Aerospace for Aluminium - where they get the helicoil insert from new.

As has been said - it will be difficult to fit - adding it from the back would leave the break off tang (installation aid) in the thread and could prevent you from using it - as the edge of the insert which has snapped can be ragged and foul the screw.

Normal practice would be the Helicoil would need to be fitted from the front - but that means opening the clearance hole in the front too..


For Load Bearing - As a rough rule of thumb..... in steel - you need the same thread depth (tapping) of good quality - correct size thread as the bolt....

In Aluminium - you need 2 x the thread depth...

So for M8 Thread - 8mm in Steel and 16mm in Aluminium (rule of thumb - not a calculation and depends on load and grade of material)

As others have said - use a longer bolt.. as long as you can.... not sure if you could also add a nut on the back for security.
 

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Is the thread repair a safe solution?
The repaired thread using a stainless or carbon heli-coil insert will be better than standard. Many manufacturers will heli-coil critical components at the design stage, ie. engine mounts etc.
Providing it’s done correctly.
The problem you have is the threaded part is in the secondary part of the hole, meaning the first section will need opened up to allow the insert to be fitted through it. This means the bolt head could be a wee bit small where the head/shoulder lands.
It may be possible to fit the insert from the other direction if it can be opened up to a through hole, be careful of this and make sure to run a tap through the heli-coil before trying a bolt. The reason for this is, depending on the type/make of threaded insert they can leave a raggy bit where the insertion tool breaks off the drive tang, some other types don’t use a drive tang.
You are looking for 1.5 x the hole diameter length of thread into most materials and more if it's into aluminium.
 

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Discussion Starter #17
Thanks a lot guys. I will look into the heli-coil method if I can get the right guy to do it. I dont dare to do it myself as Im almost certain i will introduced more damage to the clamp.
 

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The service manual says that the screw that stripped should be lubricated prior to insertion. I assume that you probably tightened it dry.
FWIW the torque the manual suggests is 24nm +/-5%
 

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The service manual says that the screw that stripped should be lubricated prior to insertion. I assume that you probably tightened it dry.
FWIW the torque the manual suggests is 24nm +/-5%
The OP stripped the threads while trying to tighten @ 20Nm as per Rizoma's instruction. If he had lubricated the threads it would have srtipped even sooner or am I missing something ?
 

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The OP stripped the threads while trying to tighten @ 20Nm as per Rizoma's instruction. If he had lubricated the threads it would have srtipped even sooner or am I missing something ?

The torque used is fine I was pointing out that it was well under the factory spec (assuming the torque wrench used was set correctly)
I can't see how lubing the threads would cause them to strip sooner. IMO it should have made insertion easier with less chance of stripping.
 
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