Shimano 11 Speed Freehub Movement

[Jim77]

Hi all

I have taken off the cassette on my Shimano 11 Speed hub and and I can move the freehub up and down by hand. In other words it is loose.

Obviously I know it shouldn’t do this but is it a case of buying a new one and replacing it?

TIA

Jim

[AndyK]

Hi all

I have taken off the cassette on my Shimano 11 Speed hub and and I can move the freehub up and down by hand. In other words it is loose.

Obviously I know it shouldn’t do this but is it a case of buying a new one and replacing it?

TIA

Jim

If you're lucky, it's possible that the freehub mounting bolt has come loose: the hollow bolt that holds the freehub body onto the wheel hub. That would give the effect you're describing. It's part (C) in this diagram. You'll need to remove the axle and bearings first to get at it, then you'll need a big allen key - usually a 10mm one.

screenshot (1).png (29.17 KiB) Viewed 655 times

. If the bolt is loose, tighten it up firmly.

If the mounting bolt is not loose then yes, the freehub is probably dead and needs replacing. Shimano has many variants of freehub body so you need to get the exact model number of the wheel hub to make sure you buy the right freehub. If the wheel hub is made by Shimano, the model number will be printed on it somewhere. (It probably starts with "WH-" or "HB-".)

That mounting bolt should almost never come loose, assuming it was installed properly. If it has come loose, that may be an indication that something else in the wheel went wrong first, so have a close look at all the other parts of the wheel hub, including any ball bearings that fell on the floor when you took it apart.

[Jim77]

Thank you for your very detailed and precise answer. I will take your advice and report back once I have looked into it.

[Brucey]

inside a shimano freehub there are two bearings, much like those inside a conventional threaded freewheel, but smaller. In a freehub, this mechanism supports the RH hub bearing and is attached to the hub using a hollow bolt. If there is free play, it usually means the freehub body needs re-shimming or replacement, but to the untrained eye it looks very similar when the hollow bolt is loose. Shimano originally meant for their freehubs to be routinely reshimmed, but today they would sooner sell you a replacement freehub body. Whether you re-shim or replace, you wind up servicing the hub bearings anyway; freehub body replacement has the distinct advantage that the DS cup is also changed (which you may like) but there is the attendant possibility that the wheel will need to be re-trued (which you may not). Once you are inside the hub, re-shimming is no more difficult than it is for a conventional freewheel, although you do need a special tool (which you can buy or make).

[Jim77]

What is the re-shim procedure?

[Brucey]

you first need to remove the dust shield/seal on the RHS of the hub; then you can unscrew the RH cup (which is on a LH thread), using a special tool.

The RH cup is also the cone for the freewheel bearings, and sits on a bed of shims, the thickness of which determines the freewheel bearing adjustment. Re-shimming usually simply requires that you remove one or more shims from the stack. If you want to get fancy, you can use the screw thread as a micrometer screw thread, using it to 'measure' the exact thickness of shims that need to be removed. It is also possible to lap the parts, which allows precise bearing adjustment, even if the available shims do not.

IME a great many freehub bodies are replaced when they could simply be reshimmed instead. Even if the bearings are a little rough they cannot slow you down, provided they are also play-free. These bearings can last well, because they normally either see load or movement, not both at the same time.

[RJC]

The hollow bolt does need to done up tight or it can unwind itself and jam into the bearings - I found this the hard way. Check the torque specs, from memory it was something like 35Nm.
I have yet to attempt any freehub re-shimming but I did buy a 'bicycle freehub body remover' tool in case the need arises.

[Brucey]

annoyingly no-one seems to make tools with a male bi-hexagon shape, leaving a choice between two types of tool for the hollow bolt, neither ideal. The hollow bolt (of course) varies in size with axle type.

The most common type of tool is a single hexagon eg. an allen key. This has the advantage that the six points of the hexagon engage very well, being almost ideally shaped. The disadvantage is that it only drives on half of the available flanks.

The alternative is a spline bit; this can engage with all 12 flanks, but the angle of each flank is wrong.

On balance I guess I prefer the spline bit; it is difficult to trump driving on all 12 flanks, even if that drive is imperfect.

[gregoryoftours]

What's the Shimano part code on your hub?

[Jim77]

Ok - an update - the hub is 105 Shimano rear hub.

I managed to find another old freehub on same hub model.

I have fitted this and there is little to no play. Certainly far less than the original.

If I feel brave enough, I may try the re-shim method on the old freehub.

Thanks all.

[NickJP]

There's a lot of variation in the allen key size needed for freehub removal on modern Shimano hubs. I have some MTB hubs where I've needed either a 14mm or 15mm allen key to remove the freehub.

[Brucey]

.....If I feel brave enough, I may try the re-shim method on the old freehub.....

This is made a lot easier if the freehub body is bolted to a wheel. I did so many of them I wound up making a special tool for working on loose shimano freehub bodies, but tbh it wasn't a big improvement over a wheel.

[Jim77]

Thanks Brucey - I will report back, if I attempt it, with my findings!