Rear Wheel Bolt - Bad setup

[Igor]

I had adjusted my chain about a week ago and yesterday I heard a clicking noise as I moved the bike in the garage, I thought maybe I'd overtightened the chain or misaligned the wheel.

So put the bike on side stand and checked, chain slack was 52mm, a bit tight maybe so thought I'd slacken it a bit and check the wheel alignment.

Went to loosen the wheel nut with my breaker bar (alway use my torque wrench to tighten it to 105Nm as per the book) Thought it was a little stiff, so gave it a good push and it began to move but didn't break loose, gave it another and heard crack noise. Checked, couldn't see anything wrong till I checked the cup on the right hand side of the bike.

See the picture below, 2 things I don't get, why didn't nut break loose in my first turn and second how on earth could the assembly shear off like that?

Needless to say I'm off to the dealer to get it fixed under warranty (I hope! I know they do everything they can to get out of that stuff) but back wheel is now loose so it's not safe to ride.....

 

[da1kini]

I had adjusted my chain about a week ago and yesterday I heard a clicking noise as I moved the bike in the garage, I thought maybe I'd overtightened the chain or misaligned the wheel.

So put the bike on side stand and checked, chain slack was 52mm, a bit tight maybe so thought I'd slacken it a bit and check the wheel alignment.

Went to loosen the wheel nut with my breaker bar (alway use my torque wrench to tighten it to 105Nm as per the book) Thought it was a little stiff, so gave it a good push and it began to move but didn't break loose, gave it another and heard crack noise. Checked, couldn't see anything wrong till I checked the cup on the right hand side of the bike.

See the picture below, 2 things I don't get, why didn't nut break loose in my first turn and second how on earth could the assembly shear off like that?

Needless to say I'm off to the dealer to get it fixed under warranty (I hope! I know they do everything they can to get out of that stuff) but back wheel is now loose so it's not safe to ride.....

That looks weird, but my nut got stuck so they had to replace it to. And the warranty was no issue,they replaced it at no cost!

 

[Ralph]

That must have been hellish tight.

 

[daveflave]

Was the thread lubricated?

 

[Ralph]

What did the thread look like that looks like more than just a overtightened nut.

 

[blueglue]

Almost looks like the bolt was tightened up overlapping the lips causing a stress fracture. Either way it shouldn't be failing like that. Let us know what Yamaha say.

 

[Igor]

It wasn't overtightened, was bang on 105Nm and I know it was sitting correctly. I never put any grease or anything on either. Reckon the nut must have seized in place but the assembly shouldn't have failed like that


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[daveflave]

You should always follow the manufacturers advice as to where and where not to use lubrication on screw threads. Manufacturers specify a torque on the nut so the bolt (or spindle in this case) is at the correct tension. The torque is not set just to prevent the nut from coming loose. Lack of lubrication on threads means that for a given torque the bolt tension is lower than it would be with lubrication. Lubrication also acts as an anti-seize which may have happened in your case???

 

[Igor]

That's the whole point, I followed the manual exactly and it does not state anything about lubricating the axle nut.

In fact if you torque up a bolt which is lubricated it will over tighten as torque settings are based on non lubricated values.

And it was exactly 105Nm. As da1kini said his nut seized also. I'm going to bring my manual with me when I get to dealer and discuss it with them


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[daveflave]

In fact if you torque up a bolt which is lubricated it will over tighten as torque settings are based on non lubricated values

If it states that a thread should be lubricated with a particular product then the torque figure will be calculate to provide the correct tension. You get a more consistent tension to torque with lubricated surfaces than dry

 

[Igor]

Ok fair point. Double checked manual and there is no lube in manual so I reckon I should be ok from warranty point


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[balki]

Its possible a bit of grit could of got into the thread (locking The nut) but the nylon (Blue bit) of the nylock nut seals onto the thread (thus preventing crap getting in there)(Look for scoring/scraping on the thread)
have you dismantled it completely yet, could you post closeup pics of the fractured edges (are there any holes/bubbles that the fracture could start from) are there smooth sections - indicating a split - undetectable until the rest ripped off ,usually the start of the weakness
Possibly just a casting defect (rather than poor quality, soft metal)

The bikes too new for the nut to have siezed and lube/no lube would not make that big a difference (ducks head to avoid flamewar)
dont worry yamaha are good with warranty claims

 

[Igor]

Just dropped off the bike and spoke to the mechanic. He confirmed never to use lubricant on axle nut (Yamaha recommend not to)

Luckily I'm off to KL with work for over 2 weeks so bike will be ready for me when I come back.


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