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2016 450SXF Rear hub snapped

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I have a 2016 450sxf and just had the rear hub snap and destroy the sprocket, chain, and scratch up my swing arm and chain guides badly. Never heard of this issue but the chain was new and loose I measured it before the ride. It snapped when I landed a jump in my backyard... Not very big jumps. Is it worth sending pics to KTM USA for awareness or is it a more common thing? 


 

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Your chain was too tight. And if it wasn't, something got in there and made it too tight ....you see the end result.

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Your chain was too tight. And if it wasn't, something got in there and made it too tight ....you see the end result.


2.5 inches before the ride almost thought about tightening it. I'm positive of that.

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Then you got the luck of a rock or something getting in there ....  You can see the folding of the sprocket.  

I could be wrong, but looks pretty convincing to me.

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Where are the missing 3 bolts?

Quote

Hmm good point...

Yeah..the only place you don't have "leftover" rim attached to the sprocket is where the bolts are missing.  Have you had the sprocket off at any time..if yes..did you use lock tight when re-installing?

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Looks to me like 3 bolts came loose and fell out then the sprocket pulled away from the hub and failed.  If you look at the sprocket and hub where the missing bolts should be you can see some oval-ling which also point to loose bolts.  I will use sprocket bolts once.  Twice tops in a pinch but after that they seem to stretch and not hold torque.  

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Getting a torque wrench to fit on to the all the sprocket nuts is impossible on initial install, due to spokes in the way.

So its hand tighten to torque guess method (with loctite and new bolts).  

torque the nut side and hold the bolt head on final torque.

this is a real critical area for dirt bikes  with a lot of power.

Also, related,  retorque spokes to spec often....esp when new!

 

 

 

 

 

 

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59 minutes ago, BlackBuzzard said:

Getting a torque wrench to fit on to the all the sprocket nuts is impossible on initial install, due to spokes in the way.

You can get Torx socket bits

 

 

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8 minutes ago, S.O.A.N.Z said:

You can get Torx socket bits

 

 

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But I read somewhere, and it makes sense, that torquing down on the conical shaped bolt head, adds considerable resistance and will not result in proper bolt torque.

Maybe this is a bit too picky.??    

So far, I have never had a sprocket/hub failure,   but I do give those bolts a close eyeball inspection when checking tubliss air pressures before every ride.

 

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Sounds like the bolts came out thanks for the help still a bummer. I did have blue locktite on the bolts, usually use red... I have used those bolts on the past 3 sprockets so they may have stretched also. I'll be sure to change the bolts and use red locktite from here on with sprocket changes.

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Looking at the pics it took me 2 sec to see "ovaling" in the hub holes and the sprocket which is worn AF btw. I've seen this happen first hand on many bikes, EVERY time I see the hub bolt holes are oval. Even if the bolts are tight they won't stay that way because that slop allows movement with constant slamming during acceleration. Once your hub holes are oval you're basically riding in the danger zone. Lol.

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Blue locktite should be sufficient. It is more likely that your bolts broke from fatigue either at the head  or the end of the threads. A full lenght bolt comming out would have done damage to the swingarm and destroyed the holes in the hub. Put your money in a good aftermarket wheel and ride on.

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