Shimano freehub fail

[murz100]

Hi
so my shimano freehub on 2020 AT has failed again . It has already been replaced under warranty
so there obviously a load of crap I’m looking for recommendations on what to change to ?
cheers

 

[Mikerb]

failed how? Maybe find out why. There must be thousands of EMTBs using the shimano freehub without problems.

 

[murz100]

failed how? Maybe find out why. There must be thousands of EMTBs using the shimano freehub without problems.

The first one wouldn’t engage so was replaced under warranty
and now this replacement won’t disengage . Maybe it’s just my bad luck

 

[Mikerb]

Is this the standard 3 pawl shimano hub? If so engagement or non engagement just sounds like the pawls being stuck either with too much grease or dirt. If nothing was actually broken it is just down to proper installation and maintenance. It literally takes minutes to remove the cassette and freehub to clean and lube. The mechanism is very simple but totally effective as long as the pawls are free to engage and disengage. Why not strip it and do it yourself?

 

[ggx]

Shimano freehubs are solid, never had issues in several bikes (from entry line until more up in the scale range). . 2 with problems? So bad luck? Or just a matter of cleaning it/maintenance.

 

[MrPeaski]

2020 160 Action Team
I had mine 'seize' the other day when i was out on a 'road' stint, I only noticed something was different as I could hear the motor ratchet when freewheeling.

Found the cause when I went to oil the chain and felt the cassette, solid to the hub. The hub is a XT FH-M8110-B 12 spd micro spline.

I downloaded the tech doc and pulled it apart. one of the internal coil springs had a couple of rust spots, so sanded it off with 800g wet n dry, little dab of grease and reassembled., and it seems to be back to normal.
The most difficult pat of the reassembly was the stupid plastic 'fingered' spacer, awkward to get back in the correct place.

As yet I haven't had a chance to actually ride it, so will have to see if it happens again.

A friend of mine has had 1 XTR 12spd microspline hub replaced under warranty.

And this is the first Shimano hub I've ever had go bad

 

[MrPeaski]

Tech Docs
Manuals & Technical Documents - (dealers manual) covers XTR, XT, SLX hubs

Manuals & Technical Documents - (XT exploded diagram)

There are a few parts within the freehub that are supposed to be run dry! no grease, oil etc.

 

[MrPeaski]

Just been looking at other sites with failed 12 spd Shimano hubs.
multiple XT M8100 hub failures

One dealer had so many customers with hub issues, he decided to do a video on its disassembly, greasing and re-assembly
(mentioned in this post multiple XT M8100 hub failures)
The video is here... Its in Portuguese, but you can turn on the auto translate to get an idea of what he is saying.

Now, when I did mine the other day, the tech docs and the video reference a piece called a 'slider'. In the video it the black plastic piece that gets placed back on the inner spring (about 3.42 mins in), in my freehub this was not present!
I have just gone back out to the garage and scrambled around looking to see if it had fallen out when taking it apart but I couldn't see it.

I Think I'll give the shop a call over the next day or so and get their thoughts

 

[murz100]

Just been looking at other sites with failed 12 spd Shimano hubs.
multiple XT M8100 hub failures

One dealer had so many customers with hub issues, he decided to do a video on its disassembly, greasing and re-assembly
(mentioned in this post multiple XT M8100 hub failures)
The video is here... Its in Portuguese, but you can turn on the auto translate to get an idea of what he is saying.

Now, when I did mine the other day, the tech docs and the video reference a piece called a 'slider'. In the video it the black plastic piece that gets placed back on the inner spring (about 3.42 mins in), in my freehub this was not present!
I have just gone back out to the garage and scrambled around looking to see if it had fallen out when taking it apart but I couldn't see it.

I Think I'll give the shop a call over the next day or so and get their thoughts

Thanks for posting this info
but To have two fail in quick succession I just don’t trust it and have swapped it out ?