Shimano Freehub Replacement

I’ve got the classic crack and slip going on with a Shimano FH-M525-SL rear hub.

As I will have to strip the axle to do a proper job of flushing and lubing it I may as well replace the whole thing.

Looking at the Shimano schematic for the hub it seems as though the only upgrades are marginal i.e. you can’t get more engagement because that would require more teeth on the hub body, obviously something you can’t retrofit! Annoyingly it doesn’t specify the freehub bolt size. I know these vary and are a pretty big allen key not included in standard sets, anyone know what size it is?

Depends on the axle. IIRC it was 10mm on a standard qr, 14mm on a through axle.

You can fit the XT freehubs to the cheaper shells, and they do last longer, but you need different spacers on the axle as the bearing cup sit’s in a different place so only really practical if you have a spare XT hub for some reason to canibalise the axle from as well.

Cheers Ben 10 mm right got it 🙂

No point upgrading by the looks of things just same again. They are definitely a bit old-skool/basic but at least you can buy every single part of the hub separately for reasonableish money.

Just buy a new hub from eBay and use it for bits. Free hubs are too expensive. Silly really. You can strip them but the Shimano tool is not avialible. Or grind a 21 mm socket to fit.

Yep buy a whole hub cheap and change cones axle etc , even the left hand bearing cup should be possible but ive not done that in years

Yep buy a whole hub cheap and change cones axle etc

I wouldn’t bother with changing bits about, you may as well just swap the hub. If you’ve any wheelbuilding experience at all it’d be almost as quick. I’m quite keen on repairing things rather than replacing but in this case
a) A new hub is <£23 at CRC
b) it’s pointless stripping the new hub down just to be left with a spare body you’re unlikely ever to use.

Sorry, that’s nonsense. You can replace ALL the wearing parts of the hub easily:

Wheel strip and build – 1hr for me (10yrs lbs experience)
Replace axle, LH cup and freehub body – 10 mintes.

Sorry, that’s nonsense. You can replace ALL the wearing parts of the hub easily

I don’t agree. The cups aren’t an easy replacement for a home mechanic.

Replace axle, LH cup and freehub body – 10 mintes.

Well, that sounds quite quick but maybe you can. The OP doesn’t yet know if he’s got the right allen key for the freehub so he might not be able to.

I know I couldn’t get the old cups out of a broken hub, take the new cups out of a donor and fit them to the old hub in 10 minutes. Along with removing and refitting a freehub and swapping over the axles, cones and bearings and adjusting them.

Cups go in and out with a hammer and screwdriver.

Still way quicker than stripping a wheel and rebuilding it.

Will be stripping the hub. It’s got to be faster/easier than rebuilding the wheel. I’ve done loads of cup and cone before so it’s no sweat. I use a ground down pedal wrench to do the lock nut and cone up, it works miles better than most purpose made cone spanners!

I did both sets of bearings about nine months back and replaced one of the cones so the axle parts will most likely be in good condition. It’s just the freehub pawls randomly sticking/not engaging.

Think the freehub is about 20 quid and like you lot said the hub is not much more so will most likely get that for spares.

To keep the freehubs lasting longer you can create a homemade grease injector for shimano freehubs from a plastic milk bottle lid, and repack them periodically:
Press fit the bottle lid firmly over the ratchet side of the freehub body, make a small hole (2-3mm) in it that aligns with the tiny bearings, inject grease through said hole until fresh grease emerges from the qr side.

So you can replace all the wearing parts can you?
Brilliant. Can you point me to free hub internals please. Not a free hub, that’s a bit of metal with bearings in it. Its the bearing that have gone, I want them.
You could well be the saviour of all those useless freehubs kicking around.

You mean the hub internals? (vs Freehub body).

You need to remove a LH bearing cup from a hub (hammer and drift) and swap if over. Then new bearings and cone.

@ mattsccm – Some freehub bodies you can. The bearings are tiny can’t remember the size TBH. There’s a tool for doing it.

What it boils down to is replacement hubs/freehubs are cheap enough to not bother. It’s sort of similar to why bottom ball joints on cars, in most cases now get replaced with new wishbones, as opposed to removing and pressing in new bushes.

I know you can do them in theory. Its those tiny bearings that are screwed. If any bright spark can find me the Shimano tool I will be so pleased.
I can’t see round the idea that a bearing isn’t replaceable. That is no more than selling a chunk of a bike not a part. And I fail to see 20 quid as a reasonable price for a few bearings.
“cheap enough to not bother” Nope.

Sorry about rant . I loath the throw away society that cycling has become.

@ mattsccm – Fair enough.

I’m not keen on it myself but reluctantly accept it in some cases and move on with my life.

You can replace the bearings, I “think” there is a tool to get in there.

You can replace the bearings but the bearing races will be ****ed – little point.

Last time I took a freehub apart I just used a a punch. Comes apart easily. I did it to check the failure mode.

ohhhhhhhh liking this bodge.

You get the tool from………

Johnny Foreigner

😆

Looks like that super b tool is listed by moore large ( very large uk trade distributor ) so should be easy to get in the uk.

Well that was a piece of piss, had a 10 mm in my set which was nice.

The new hub (Shimano Deore M525A) has revised freehub race, seal and cone arrangement (didn’t look cross compatible). The new cone being accessible from outside the freehub rather than tucked inside, which made it easier to fit. Didn’t have to lock it off on the drive side first, slide the whole axle in, then lock it off on the non drive side.

Tune in next time for another exciting episode of Chester’s Riveting Repair Odyssey.