Shimano XT M785 Freehub jamming

Jim Junkie

Used to sell drugs, now he just takes them
Hi All,

I foolishly laced up some wheels somewhat recently with some Shimano XT hubs - M785 rear and M788 front to be exact.

Recently, after about 400km's on them, the rear freewheel has started intermittently jamming up. I'll be cruising along and it just sucks freezes and throws the chain off. Sometimes a bit of a clunk will be all it does and it spins again, other times it needs some encouragement. It will occasionally decide it's OK for 30km of riding, sometimes 30m.

Has anyone come across this before and know what the cause is? A quick google search seems to indicate it's moderately common, but no reasons apparent. It seems to be a problem more apparent with clydesdales & hard use too. I'm guessing it's just not up to the heavy abuse as much as it should be.

So, I've learnt my lesson. I'm planning on cutting my losses and just re-lacing the wheel with some Hope Pro2 Evo hubs to be done with it. I've got the time and it would give me peace of mind that I'm not going to rip the mech off mid ride or something.
 

Flow-Rider

Wheel size expert
Sounds like the pawls are grabbing in the freehub, worn or broken springs or the lube is too thick.
 
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Jim Junkie

Used to sell drugs, now he just takes them
Sounds like the pawls are grabbing in the freehub, warn or broken springs or the lube is too thick.
That was my guess, I'll be pulling it apart to inspect.

Geez, a more thorough Google does not cast a good light on these hubs. Really should have read more into it before trying to save money on the wheels of all places.
 

MountGower

Likes Dirt
That is what happens when a Shimano free hub needs replacing. It has happened to me once after a very respectable life span. I have big Ks on a Pro2 wheelset and less on two Pro2 EVO sets and can't knock them, but weigh it up against $40 and five minutes.

Definitely keep pedaling when it happens in the mean time and get it done before your next ride of any distance.

EDIT: I haven't seen the most recent version, but you may struggle to get it apart. Please post back if it can be opened and reassembled. Chhers.
 
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Flow-Rider

Wheel size expert
That was my guess, I'll be pulling it apart to inspect.

Geez, a more thorough Google does not cast a good light on these hubs. Really should have read more into it before trying to save money on the wheels of all places.
I have one that has been thrashed and lasted the distance. The replacement freehubs are pretty reasonable in price.
 

Jim Junkie

Used to sell drugs, now he just takes them
I have one that has been thrashed and lasted the distance. The replacement freehubs are pretty reasonable in price.
New hubs. As for freehubs at a reasonable price, well that depends on what your view of reasonable is. $60 (Chain Reaction) is fairly cheap, but when weighed up against the cost of the entire hub at $53, I'm not so sure.

I also have one that has been thrashed & lasted the distance. It's an older model so I suspect it has different internals, but it's done more than it's fair share of off & on road riding no with no troubles at all. My research indicates that it's only a certain model of freehub that has this issue, which is mostly restricted to the M775 and M785.

Information I've found on disassembly of these seems to show it's possible, but not too easy. Either way, I like a challenge so I'll be getting into it as soon as I have some time. The main problem for me is the loss of trust (more so after a bit of reading into the issue with this particular model), and the potential damage it could inflict. With a seized dérailleur, I could be quite easily looking at $100-$200 damage at the rear of the bike. I'd prefer not to take the risk, even though I recognise that a large portion of it is just perception. I'll still see if I get any luck on the warranty and possibly use them as replacements on my commuter when that hub eventually dies, but not on the Blur any more.
 

slippy

Likes Bikes and Dirt
If that's the freehub that requires a 14mm allen key to take it off, then just cut your losses and replace. The design is a fail and you'll keep having the same problem.
 

Haakon

Call me Ken, whoreken
If that's the freehub that requires a 14mm allen key to take it off, then just cut your losses and replace. The design is a fail and you'll keep having the same problem.
This. They dont come apart easily and are fooked anyway if they ever get bad enough to cause problems. Toss it.

Another reason I don't like Shimano wheels. Its weird, they do everything else really well, but persist in these awful freehubs and god dammned bloody cup and cone nonsense...
 

Jim Junkie

Used to sell drugs, now he just takes them
If that's the freehub that requires a 14mm allen key to take it off, then just cut your losses and replace. The design is a fail and you'll keep having the same problem.
Yup, it's that one alright.

This. They dont come apart easily and are fooked anyway if they ever get bad enough to cause problems. Toss it.

Another reason I don't like Shimano wheels. Its weird, they do everything else really well, but persist in these awful freehubs and god dammned bloody cup and cone nonsense...
I'm also a little confused with this. Nearly everything else Shimano that I've used has been of good quality, I just can't understand why that doesn't apply to the hubs. Maybe for the Alivio or Deore end of things, but XT?
 

slippy

Likes Bikes and Dirt
Yup, it's that one alright.
Get out quick. Your whole life is cursed until you get that evil talisman out of your possession. Just make sure whoever you give it to truly deserves it, with great power comes great responsibility.
 

Flow-Rider

Wheel size expert
Don't jinx me you witches :rant:, mine is fine. Yeah, they are cheap shit, I have seen people snap the free hub in half.
 

Jim Junkie

Used to sell drugs, now he just takes them
Get out quick. Your whole life is cursed until you get that evil talisman out of your possession. Just make sure whoever you give it to truly deserves it, with great power comes great responsibility.
And all becomes clear, it's the hubs fault. I have been wondering why my luck has been so rotten lately, at least now I know.

Now I just need to decide how I'm going to unload this thing. Surely there's a deserving individual somewhere, I hear they're perfect for e-bikes.
 

Haakon

Call me Ken, whoreken
I have a pair of MT65 (SLX) wheels on my Anthem, they were supplied as a warranty exchange when the OE wheels went wobbly on the first ride. They are tubeless and straight pull so i thought score.

To their credit, they have stayed straight through some hard yards, and ride well enough. But the bearing are never properly smooth and they are a screaming pain in the arse to get set up not too tight not too loose... Freehub died pretty early on, and I think its underengineered and poorly made.

Much happier with the tightarse tuesday Mavic Crossrides on the other bike.
 

Emigna

Squid
Mine suffers the same problem, but its 4 years old or so.

Ive found dribbling some heavy duty lanolin oil in behind the freehub and spinning it fixes the problem for a while. I leave the wheel on its side overnight for the oil to work down.

Lanolin oil is also a top chain lube.
 
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