Shimano M550 rear hub question

Hi,

First post here

After coming across this forum, and getting inspired like, I dug out my old Orange Clockwork from the shed and started stripping it down to renovate. Hasn't been used since 96.

I'm no expert here and sort of finding my own way. The group set appears to be all Deore LX M550.

I got to stripping down the rear hub but can't get the free hub off. Online docs tell me that a 10mm Allen key fits an internal hollow bolt, but that's not the case. I worked out that it was a spline, but it doesn't want to seem to come off.

I'm confused as all the M550 documentation points towards a 10 mm hex key. Any suggestions about this?

In the meantime, as there seems to be a little play in the free hub, I thought I'd have a go at building a wheel with a XT 780 hub and Mavic 331 rims, so if nothing else, I could use it as a spare and will ( hopefully) have learned to build a wheel

You shouldn't need to take the hub body off to strip the wheel - you need the splined freehub tool, a good spanner and a chainwhip (to stop the freehub spinning as it loosens in the "free" direction) to remove the cassette from the freehub body.

If you do want to take the freehub body off afterwards the allen bolt should be located inside the body behind the bearings (it's hollow because the axle goes through it.

Hi,

Thanks for getting back to me.

I have the cassette off already - just trying to remove the free hub, but an Allen key wont fit - the hole through the centre takes a spline tool about 12mm or so. That's what's confusing me as everything I read says a 10 mm key will do it, but it clearly doesn't.

I tried the spline tool but it won't budge, hence my wondering whether it should indeed come off or is part of the hub? The documentation indicates that the M550 hub is separate though?

I had one that wasn't 10mm, it must have been 11mm bihex. I couldn't find a 7/16" allen key so I used a bit of 7/16" hex bar in a socket, it worked great.

Yep, some hubs take 11mm allen keys. No idea on this one though I'm afraid!

As stated before, unless there is something damaged within the freehub body or you want to swap an 7speed to 8speed or so you don´t have to take it off the hub body in order to service the hub.

If it is an M550 hub then it will have a 10mm allen key fitting hollow bolt holding the freehub body onto the hub shell.
If there is a spline or anything other than a 10mm bolt then it isn't an M550 hub.

As far as I know there are a few hubs out there that use an 11mm or a 12mm allen key bolt, such as Joytech, but no Shimano hubs.

Best bet would be to post up some photos of the hub to see if anyone can identify it and suggest a solution.

Thanks for the help.

We managed to sort it eventually although I feel a tad embarrassed

What I thought was a 10 mm Allen key was in fact a cheap Aldi 10mm key look alike which was in fact 8mm

So the 10mm did work after all. Feel a bit of a fool now.

We've all made mistakes like that!

I have a lot of crap allen keys rattling around in my toolbox that I really ought to get rid of but they do come in handy when I need to extend the handle of one to release a stubborn bolt (I chuck them once they get rounded off or bend/snap from this kind of abuse - I actually tried to use one tonight to adjust my brake cables & it was about 1/2 a mm or more smaller than a proper 5mm...

Yes, I have mucked up bolt heads that way in the past (and have done the same when I borrowed my dad's set as a kid and picked up the imperial set instead of the metric one.

I do have a decent set of keys somewhere (got them from Wickes, they're the long arm type with the ball-shaped ends) but I never seem able to find them when I need them!