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Glad I could help Adam....... it's great you're back on the road.....enjoy!

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I don't think this failure scenario is due to loose sprocket nut to start with. It will end with it being loose after wearing and failure of the solid stack though.

I have been checking my bike for tightness and check it as part of my tire changes(every 3 months). I have a 2014 F3 800.

Initially it was always tight. But then I found that I could snug it up a little each time. Never wobbly or physically loose. Just less torque than spec. So, I decided to at least do a hub service over the winter to at least keep bearings happy and lubricated.

After my hub service I haven't found it loosening yet.

I think as the stack heats up it is stretching/compressing the stack. If the hub is running with less lubrication it will overheat. Once it cools something will be loose. Not sure if this is due to axle stretch or due to the metal stack compressing though. I would need a new set of components to compare and a way to measure with high accuracy.

Knurl is right that this is a solid stack. If anyone can measure a new vs old axle and stack length we would get the answer.

In the meantime... service your hubs and check the hub temps. Should never get blistering hot but will be warm normally.
 

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I don't think this failure scenario is due to loose sprocket nut to start with. It will end with it being loose after wearing and failure of the solid stack though.
The stack and the axle rotate as one, there can be no wear or water intrusion unless the sprocket nut was not tightened correctly......

An alloy nut isn't going to stretch a heat treated steel axle, won't happen!

Given that Atom's dealership used a screwdriver and hammer to adjust the chain, what's the chance they didn't
torque the sprocket nut correctly????

If I had a 2nd Gen MV, I'd be scouring the Forum and eBay for a 1st Gen cush drive.......we've had zero failures
I have over 35,000mi on my Brutale 910R, one of the Aussies is getting 4,000km to a set of rubbers

Reduce your pinch bolt torque to 15lbft/20Nm MANDATORY for bearing life!

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The stack and the axle rotate as one, there can be no wear or water intrusion unless the sprocket nut was not tightened correctly......

An alloy nut isn't going to stretch a heat treated steel axle, won't happen!
I fully accept that the stack should, in theory, be solid and once torqued correctly and staked with the clip it shouldn't come loose. However, I've found my hub nut loose on several occasions and re torqued it. Each time the clip is still in place and properly engaged with one of the holes in the axle. I've taken to securing the clip further with a cable tie to no avail.

Something is wrong with either specifically my stack or the design in general. I fear at some point there will be contact such as experienced by the OP. I continue to keep a watchful eye on both the nut and the gap between the sprocket carrier and outer face of the hub.
 
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I fully accept that the stack should, in theory, be solid and once torqued correctly and staked with the clip it shouldn't come loose. However, I've found my hub nut loose on several occasions and re torqued it. Each time the clip is still in place and properly engaged with one of the holes in the axle. I've taken to securing the clip further with a cable tie to no avail.

Something is wrong with either specifically my stack or the design in general. I fear at some point there will be contact such as experienced by the OP. I continue to keep a watchful eye on both the nut and the gap between the sprocket carrier and outer face of the hub.
Sounds exactly like the issue I had Bumpkin, you've probably seen the thread with the all the pictures I had. I put it down to my error and replaced sprocket carrier n rubbers etc myself but when I showed the parts to the dealer they replaced the whole lot, hub, carrier, bushes etc all under warranty. Have you taken it in for them to have a check?
 

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Sounds exactly like the issue I had Bumpkin, you've probably seen the thread with the all the pictures I had. I put it down to my error and replaced sprocket carrier n rubbers etc myself but when I showed the parts to the dealer they replaced the whole lot, hub, carrier, bushes etc all under warranty. Have you taken it in for them to have a check?
Thanks for the reply. Yes, have read the thread both as it unfolded and again very recently. Will speak to dealer and get them to send a set of cush drive rubbers and at that stage will remove and inspect. I can still see a gap between the carrier and the hub, no aluminium swarf yet. Will be booking in for 2 year service ahead of my warranty expiration as well as clutch switch and a look at the hub by them. Unfortunately they're 100+ miles away so this will be late March/early April.
 

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Did you get the hub and everything to look at? Isn't the grease supposed to resist corrosion? Was there grease in there or was it dried out?

Picture of the water damage on Chris' axle.....water has been getting in for a long time!
 

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Did you get the hub and everything to look at? Isn't the grease supposed to resist corrosion? Was there grease in there or was it dried out?
Yes, I had the complete hub assembly
There is never* grease on the axle, the seals keep the grease in the needle bearings, grease was just fine

*I grease my axles with waterproof grease, but that's me

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I was asking about grease for the bearings but yeah I greased the axle as well to protect from water/corrosion. Were the bearings dry?

Yes, I had the complete hub assembly
There is never* grease on the axle, the seals keep the grease in the needle bearings, grease was just fine

*I grease my axles with waterproof grease, but that's me

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?????

I was asking about grease for the bearings but yeah I greased the axle as well to protect from water/corrosion. Were the bearings dry?
WTF.....Did you read my last post?????
 

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Ha... missed that last part.

Are any of the parts used as spacers aluminum? My front axle has an aluminum spacer (f3 800) and the axle was overtightened by the shop after a tire change. It resulted in a bearing failure from side loading. Don't overtighten the front axle or the rear axle nuts people!!!


WTF.....Did you read my last post?????
 

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The centre spacer in the hub is aluminium.
It won't crush when tensioning the sprocket nut to 220nm.
 

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I have info that some are aluminum and some are steel. Maybe steel was used to avoid fusing of the two dissimilar metals? I'm sure if everything worked as it should it wouldn't crush but with the increased strength of steel along with it not fusing I'd chose the steel option.

What are your thoughts on why the sprocket nut loosens up? Its a solid stack and safety clipped in place. I think problems begin when the lubrication fails... things heat up and expand... bearings run dry and fail.

So I think people need to be better about rear hub servicing. Make sure to grease properly and get the torque correct. Steel spacer would just add the benefit of being stronger and not fusing as well.

The centre spacer in the hub is aluminium.
It won't crush when tensioning the sprocket nut to 220nm.
 

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Ha... missed that last part.

Are any of the parts used as spacers aluminum? My front axle has an aluminum spacer (f3 800) and the axle was overtightened by the shop after a tire change. It resulted in a bearing failure from side loading. Don't overtighten the front axle or the rear axle nuts people!!!
airjawed;
Obviously you don't understand the problem.......neither does MV

1st Gen front wheel bearings are 6907-2RS they are "Extremely Light Duty Class" bearings, no one with an
IQ over room temperature would use them
1st Gen hub ball bearings are 3810-2RS, a bearing for 1-2hp DC stepper motors in robotics......I can
collapse the inner race 0.004" with my left hand......and they want to put 200hp through it>:)

2nd Gen hub bearings are 6810-2RS about 1/2 the size of the POS in 1st Gen hubs>:)

On my front axles......
Early 1st Gen (large axle) I tighten them with my fingers ONLY, no side load
Late 1st Gen (small axle) I tighten them and then until they touch and then back the nut off, no side load

I have ~ 7 swing arms the chain side needle bearings are almost always hammered out......wrong bearing
The ride height adjuster bearings couldn't be any smaller

See a problem here?????

The recommended pinch bolt torque of 28-32 Nm will crush any low clearance 3810-2RS bearing

Don't go over 15lbft/20Nm

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I have info that some are aluminum and some are steel. Maybe steel was used to avoid fusing of the two dissimilar metals? I'm sure if everything worked as it should it wouldn't crush but with the increased strength of steel along with it not fusing I'd chose the steel option.

What are your thoughts on why the sprocket nut loosens up? Its a solid stack and safety clipped in place. I think problems begin when the lubrication fails... things heat up and expand... bearings run dry and fail.

So I think people need to be better about rear hub servicing. Make sure to grease properly and get the torque correct. Steel spacer would just add the benefit of being stronger and not fusing as well.
Never seen or heard about MV using a steel centre spacer.Steel is not required because aluminium does the job and does not crush at all when the sprocket nut is tensioned.
 

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Might be the problem of galvanizing then?


My car went from aluminum front uprights (suspension) to steel in later model years. There were many horror stories of parts fusing/galvanizing and essentially requiring the entire assembly to be replaced. Bolt on hubs for example could not be replaced... later they went with steel and pressed in versions.


Lots of things to consider I guess.


Like I said.. no harm in going to steel other than a slight weight disadvantage. But galvanization less likely and it is stronger, not that aluminum is not strong enough, but I'll swap to steel if I find mine to be aluminum.


Never seen or heard about MV using a steel centre spacer.Steel is not required because aluminium does the job and does not crush at all when the sprocket nut is tensioned.
 

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When I tighten the front wheel to high end of spec it starts to side load and drag the bearing. I know the shop went way over and damaged my bearing. So, now I spin the wheel by hand and tighten to the point where it is just there at side loading like you. I figure the design is such that the pinch bolts keep it in place anyway. No need for heavy hands... its all engineered to work if procedures are followed.


Aluminum does get crushed.. not saying it crumples like food foil aluminum but the fact that the bearing drags if you over do it says it does.


Hope you guys have a great weekend ahead with wheelies and knee dragging. Stay safe everyone.


airjawed;
Obviously you don't understand the problem.......neither does MV

1st Gen front wheel bearings are 6907-2RS they are "Extremely Light Duty Class" bearings, no one with an
IQ over room temperature would use them
1st Gen hub ball bearings are 3810-2RS, a bearing for 1-2hp DC stepper motors in robotics......I can
collapse the inner race 0.004" with my left hand......and they want to put 200hp through it>:)

2nd Gen hub bearings are 6810-2RS about 1/2 the size of the POS in 1st Gen hubs>:)

On my front axles......
Early 1st Gen (large axle) I tighten them with my fingers ONLY, no side load
Late 1st Gen (small axle) I tighten them and then until they touch and then back the nut off, no side load

I have ~ 7 swing arms the chain side needle bearings are almost always hammered out......wrong bearing
The ride height adjuster bearings couldn't be any smaller

See a problem here?????

The recommended pinch bolt torque of 28-32 Nm will crush any low clearance 3810-2RS bearing

Don't go over 15lbft/20Nm

:wink2:
 

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airjawed;
Either your spacer is too short or the hub is too wide (same effect)

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When I tighten the front wheel to high end of spec it starts to side load and drag the bearing. I know the shop went way over and damaged my bearing. So, now I spin the wheel by hand and tighten to the point where it is just there at side loading like you. I figure the design is such that the pinch bolts keep it in place anyway. No need for heavy hands... its all engineered to work if procedures are followed.


Aluminum does get crushed.. not saying it crumples like food foil aluminum but the fact that the bearing drags if you over do it says it does.


Hope you guys have a great weekend ahead with wheelies and knee dragging. Stay safe everyone.

Front wheel spacers can be slightly too long or too short from the factory which puts load on the bearings.
The centre spacer in the rear hub has a different job as it keeps the inner ring for the needle bearings at the correct width.
Here is some reading for you-


http://www.mvagusta.net/forum/attachment.php?attachmentid=222290&d=1428300588
 
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