Shimano hub bearings keep working loose

[greenmeansgo]

The hub in question is a deore front (MTB, disc) hub, with cup and cone bearings, and has had this problem for a long time.
After adjusting the cones and tightening the lock nuts, it's only one ride before there's play in the bearings again.

I don't think there's a problem with the axle thread, or I wouldn't be able to tighten the lock nuts against the cones. Logic would suggest that if they come loose, it's because I've not done them up tight enough, but I've tightened them as much as I dare.

What is wrong/what can I try?

[robgul]

The hub in question is a deore front (MTB, disc) hub, with cup and cone bearings, and has had this problem for a long time.
After adjusting the cones and tightening the lock nuts, it's only one ride before there's play in the bearings again.

I don't think there's a problem with the axle thread, or I wouldn't be able to tighten the lock nuts against the cones. Logic would suggest that if they come loose, it's because I've not done them up tight enough, but I've tightened them as much as I dare.

What is wrong/what can I try?

New balls - try fitting - you may have some "flats" on a few balls which will affect the "tension" where the cone meets the balls.  I've had a similar instance with a customer's bike and replacing the balls fixed it.

Getting the cones tightened correctly is a bit trial and error - are you giving the wheel a really good spin each time you check the tension and adjust the cone/locknut combo?

[Wobbly John]

Check the cups aren’t cracked. Only seen it happen a couple of times, but similar symptoms.

[aidan.f]

And, as hopefully you have an internal cam QR skewer it will compress the axle, leave a bit of float when setting up the bearings.

[greenmeansgo]

Thanks. I'll try new ball bearings tomorrow, along with a good inspect!

[robgul]

Thanks. I'll try new ball bearings tomorrow, along with a good inspect!

To add to my comments - when you have the wheel at what you think is correct put it in the bike and give it a spin and lateral pull - as suggested there is often compression from the skewer.   AND don't go mad with the skewer tension - my method : push the lever over with the "base of your thumb" (the fleshy bit where it meets your hand) - it needs to be tight enough to just leave an impression in the flesh when the lever is closed. 

[Tim Hall]

Another thing that gives the symptoms that worn balls give is worn cups. This isn't such an easy fix, as it generally means scrapping the hub*.

Have a look in the clean, grease free cup for signs of wear or pitting.

*Cups are mostly non replaceable. I think Campag do/did a hub with replaceble cups but that's about it.

[greenmeansgo]

So far, it would seem that new ball bearings have done the job. I'm sure I would have replaced them several times already, but anyway, happy that it seems to be ok so far!