Broken bottom Yoke / Triple tree

trevorpacker

trevorpacker

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Bottom yoke clamp broke on my 2015 961.
4000 trouble free miles until this.
Dropped it off at MCC on Wednesday (1000 mile run from Houston) will be interesting to see how long it takes to get the part.


Broken bottom Yoke / Triple tree
 
Under what conditions did this happen? Did you hit a sharp bump? Or did you just find it separated one day? I can't imagine this happening. :shock:
 
I would suggest it has been over tightened. Lets just hope the factory doesn't blame you!

The material is not thick in the broken area. Plus there are 3 bolts applying torque on it... and 3 bolts can apply a lot of torque! Finally, look at the gap. It has not only crackd, it has opened up. The only thing causing the material to pull away and open up like this is those 3 bolts.

So, over tightening of those 3 bolts, plus vibration or a bad road bump or two and voila.

That's my theory anyway.
 
Hi trevorpacker,

We have not seen a warranty claim for this yet, however this is obviously not acceptable and all I can do is apologise for the situation. Please be assured we will get the parts out to your local dealer (MCC I believe) today on express shipment.

We will have the damaged part returned to us for detailed analysis as we have NEVER seen this happen before.

Apologies again

Simon
 
Hello Trevor , were you driving the bike to Chicago and noticed this ? Was MCC part of your trip plans ?
 
Same crack, same place, front of lower left tripe tree clamp This happened on the race bike, so I did not file a warranty claim. I was going to make a new one out of billet, but the factory already had billet units for the Domi. I bought one new cast unit and one billet

The radius on the outside of the clamp where it blends to the clamping flange needs to be about 3 time larger. This would not effect the counter bores for the screw heads, as an end mill could easily start the interrupted cut into the radius.

Before we learned that a billet was available from Norton we scanned and redesigned the triple tree with a much larger radius in the area described above
 

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Hi John , WOW , good to know . Seeing I have a Sport a billet version will NOT be available I assume ?
 
Simon, thanks for your prompt response. Your presence on his site is much appreciated. Yes my dealer is MCC in Villa Park, Illinois.

in answer to some of the questions, just noticed this one day, not related to any bump or knock that I am aware of, bike has no damage.
Decided to load the bike on a trailer and drive to MCC from Houston. Long drive but I purchased the bike from MCC and the distance is only slightly longer than the next nearest dealership.
 
Hi Trevor , Thanks for the answer. Now that we have seen 2 of these failures that would be the beginning of a trend . IF Norton make an improved version I could install it myself. Are you getting the new map while you are there ?
 
trevorpacker said:
Bottom yoke clamp broke on my 2015 961.
4000 trouble free miles until this.
Dropped it off at MCC on Wednesday (1000 mile run from Houston) will be interesting to see how long it takes to get the part.


Broken bottom Yoke / Triple tree
Click to expand...
Holy cow.
But just so you know, I just bought the polished versions and I received mine in less then a week straight from England.
 
Hi Tony, sent my ECU to MCC October last year for remap after I fitted the short Motad system.
 
trevorpacker said:
... sent my ECU to MCC October last year for remap after I fitted the short Motad system.
Click to expand...

The newer map wasn't available then, was it? While your bike is there you should get the latest one.
 
TonyA said:
Hi John , WOW , good to know . Seeing I have a Sport a billet version will NOT be available I assume ?
Click to expand...


All of the Norton yokes on all of our current (Year 2010 onwards) bike ranges are machined from solid billet ! No forging and certainly NO CAST yokes ! The surface finish is a result of the shot blasting and anodising after treatments.
 
contours said:
trevorpacker said:
... sent my ECU to MCC October last year for remap after I fitted the short Motad system.
Click to expand...

The newer map wasn't available then, was it? While your bike is there you should get the latest one.
Click to expand...

No , The newest maps were not available at MCC at that time . But maybe Trevor is happy with his current map ? I was not happy so now I have the latest version I could get which works well for me. I thought Norton was calling it the 2016 Aftermarket Map for the SC ECU . Thats what Richard Pearce (UK) told me .
 
[quote="G81 Can Cycle)'

The radius on the outside of the clamp where it blends to the clamping flange needs to be about 3 time larger. This would not effect the counter bores for the screw heads, as an end mill could easily start the interrupted cut into the radiue[/quote]


John, I agree 100% that the radius could and should be tripled!

The clamp on my SF does appear to be billet then blasted, exactly as Simon said!
 
I assumed it was a casting. The look of the material at the fracture had the look of a failed casting. I have looked at the part more closely, and can see it has been machined

I discussed this failure with the parts guy at Norton UK. I told him I was scanning the part and was going to make a billet unit. He explained that Norton made a billet unit and it was for the Domi, so I purchased one. He did not explain that all the yokes were billet.

I did scan the part, and redesigned areas that our FEA (finite element analysis) showed as weak areas. But we never put it into production.

John
 
G81 Can Cycle said:
I assumed it was a casting. The look of the material at the fracture had the look of a failed casting. I have looked at the part more closely, and can see it has been machined

I discussed this failure with the parts guy at Norton UK. I told him I was scanning the part and was going to make a billet unit. He explained that Norton made a billet unit and it was for the Domi, so I purchased one. He did not explain that all the yokes were billet.

I did scan the part, and redesigned areas that our FEA (finite element analysis) showed as weak areas. But we never put it into production.

John
Click to expand...

Good to know, Thanks for the info John. What software are you using?
Bob
 
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