I have a XT 775 rear hub (the new kind that uses the 5mm aluminium locknut, not the regular old cones that I know and love).
Anyway, the rear hub is either too loose or too tight.
And if I start with it loose, it self tightens.
Even the local shop couldn't fix it.
Anyone run into this problem?

http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Deore-XT/SI_3CZ0A_002/SI_3CZ0A_002_EN_v1_m56577569830621150.PDF

It looks easy on the diagram with the allen key and spanner.

Even with cup/cone it's a case of feel.

I had problems with 2 sets of wheels-must be me?

Well after a year I finally changed the grease from white lithium to heavier boat grease the teams use and presto all my adjustments became easy.

What grease are you using?

I'm putting Phil Wood grease all over the place.
But for the same price I was thinking of buying my own mechanic and keeping him in the shed.
Cheaper and probably won't have any problems fixing the rear hub

Someone suggested Locktight on the locknut, but I can't even get it adjusted right.

I've had the same problem recently.

Started off with a bit of play which I tightened out. Fine for a while. Then it loosened again so I replaced all the grease. Fine for a bit…

Next tactic was superglue on the lock nuts which, again, worked for a while.

Now I can't get rid of the play without nipping it up too tight so I'm going to replace the bearings and glue the lock nuts on this evening. Report to follow…

I got one of these a while ago and the locking cap design it is a real pain in the ass compared to having a locking nut to tighten against the cone nut. I spent ages adjusting it just right, because unlike the old version where using a jig and a QR I could compress and hold the axle still as I adjusted the cup and nut, as described in the bennets guide, this one cant be tightened with the QR in place. That means you almost always adjust the cone slightly when trying to clamp the locking cap against it. I found the only way to get it right was to set the play in the bearings using the jig and QR, then once just right, cafefully remove the wheel from the jig/bike without anything moving, then get an assistent to carefully hold the oposite side of the hub with a spanner to stop the axle turning whilst I used two hands to hold the cup still with a spanner and the other on the allan key in the end cap. Still took a couple of goes untill it was perfect. Ive had no trouble with them backing off though?

I've got an XT rear that has knackered threads where the freehub bolt screws in, funnily enough that had the same symptoms, I couldnt get rid of the play no matter how much I tightened it, until it was too tight,,, dissassembled it and the freehub practically fell off. Turns out the threads were duff! I reckon this would have been a warranty issue had I been the original owner of the wheels..

stuartie_c, you mentioned replacing the bearings.
I bought an axel/bearing kit ($75 Canadian) and it didn't fix anything.
It looks like warranty time . . . which sucks because the riding is perfect right now.
Oh well, should be back on the bike come November.

while we're here can i slightly hijack and ask that while you've all got your hubs stripped can someone count how many bearings there are in the drive side?? thanks!

Strange that you mentioned this.
When the mechanic took apart my hub, he said it was missing one ball bearing. Not sure which side tho.
When I work on mine (in a few days) I'll let you know.

I bought new bearings on the way home from work today; cost me £1 for a pack of 23. Seemed an odd number.

The drive side had 13 balls in it, loose. I removed the seals and cleaned the cups and cones thoroughly – all seemed fine with no sign of pitting. New balls in with lots of bearing grease.

Non-drive side had 10 bearings in a plastic cage. I ditched the cage and just stuck 13 balls in this side too and packed it all up with grease, re-assembled, swore a lot and eventually got it so there is no play, though it is a wee bit tight (I reckon it'll "bed in" after a couple of rides).

Fairly easy job once you understand how it all fits together, though it remains to be seen if it will run smoothly and be free of play.

The Shimano tech. docs are useful.

Papawheelie, the bearing cage on my rear wheel was complete but there was one less loose bearing than the shimano doc's said their should be, I put this down to the previous owner of the wheels servicing them but if you've also got a missing bearing then I owe the previous owner an apology with regards to my email, sorry previous owner, maybe you hadn't had them to pieces!!!!

Quality of these wheels is shocking for a Shimano product, all other Shimano stuff I have owned with the exception of these wheels has been indistructable and first class.

Quality of these wheels is shocking for a Shimano product

Curious thing is that the front wheel is perfect, but the rear one has been trouble for me.

Having overhauled it last night, I'll keep the jury out for a while, but I can't say I'm too impressed TBH.

Curious thing is that the front wheel is perfect, but the rear one has been trouble for me.

same here, I'm looking for a second hand rear wheel or hub at the moment but I reckon I'm just going to sell the front and build a set of something else with the change…..

If anyone needs a set of spare M775 spokes or a rim I might be able to help 😉

I've commented on posts about these before, I think they're utter shite and the idea that a premium range like XT has caged bearings is laughable.

My freehub body has had a massive ammount of wobble from day one which made indexing the gears a right bastard; I decided to get it as good as possible and decided I wanted to ride the bike rather than rebuild with a different hub.

I thought I was missing a bearing when i came to sort out the loose axle on my six ride old hub but assumed I must have just lost one, since my skills aren't up to those of a Malay that does it all day long. While it was apart I found my axle was bent.

I also replaced a freehub body from one of these that jammed on a very lightly used hub, I did reassemble the hub and get the bearings feeling nice but it was more hassle than the old ones.

I don't like to air dirty laundry in public, and must add that the UK importer Madison always did a top job dealing with warranty on all products I sent them but Shimano need to buck their ideas up.

I am interested in the fact that you sent your wheels back directly to to Madison, who were you in contact with there?