Author Topic: Free hub play  (Read 512 times)

quixoticgeek

  • Mostly Harmless
Free hub play
« on: March 05, 2019, 05:03:05 pm »

I have a free hub on my wheel, it's a shimano MTB 135mm disk hub (Deore XT FH-M6000), it's done about 10000km. I just noticed when replacing the cassette that there is a little play in the freehub. With the cassette installed and the wheel fitted to the bike, there is no play.

Is this an indication it's time to replace the bearings? or is it the freehub body unit that needs replacing?

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Re: Free hub play
« Reply #1 on: March 05, 2019, 10:15:33 pm »
it isn't quite normal for there to be free play in the freehub bearings which disappears when the wheel is installed.  It may indicate that bolt #9 here

https://si.shimano.com/pdfs/ev/EV-FH-M6000-4196.pdf

isn't tight.

If there is play in the main hub bearings when the wheel is out, which disappears when the wheel is installed and the QR is tightened, this means the hub is perfectly adjusted.

If there is play in the freehub body bearings this usually persists when the wheel is installed. It can be adjusted out by re-shimming the freehub body.

cheers

Re: Free hub play
« Reply #2 on: March 06, 2019, 09:39:22 am »
Most freewheels wobble like Weebles.  It makes no real difference to anything, since the freewheel bearings never have to work under load.  It's actually helpful on a singlespeed if your chainline is a bit off, because it allows the sprocket to align itself.  Singlespeeds are nearly always quiet, whereas fixies can be rather vocal.
Never tell me the odds.

Re: Free hub play
« Reply #3 on: March 06, 2019, 11:25:24 am »
that's not quite right; the bearings never move under load only if there is no play in the bearings.

 If there is play in the freehub bearings then the freehub body is usually squirming around under load. You can tell this is happening  because freehub bearings that are slack already just get slacker and slacker, whereas play-free freehub bearings stay good for a very long time because they aren't squirming around under load. If you take a freehub body that is wearing, and reshim it so that it doesn't have free play any more, normally the wear rate then diminishes to virtually nothing.

It is virtually impossible to say how much power the squirming absorbs, but it won't be zero.

For several reasons it is a bad idea to ride around with slack freehub bearings and you would be quite mistaken in thinking "it doesn't matter".

cheers

quixoticgeek

  • Mostly Harmless
Re: Free hub play
« Reply #4 on: March 06, 2019, 12:02:30 pm »
it isn't quite normal for there to be free play in the freehub bearings which disappears when the wheel is installed.  It may indicate that bolt #9 here

https://si.shimano.com/pdfs/ev/EV-FH-M6000-4196.pdf

isn't tight.

Oh goody. To get to that I'm gonna need pull the whole thing apart. If I am going to that effort is it worth replacing bearings at the same time?

Quote
If there is play in the main hub bearings when the wheel is out, which disappears when the wheel is installed and the QR is tightened, this means the hub is perfectly adjusted.

If there is play in the freehub body bearings this usually persists when the wheel is installed. It can be adjusted out by re-shimming the freehub body.

Just checked, and there is play in the cassette/freehub when it's installed in the bike, but no play in the wheel. How does one re-shim the freehub body?

Looks like the freehub is Y3SW98060, which I think is the same as the freehub body on my spare wheels.

Would swapping the freehub from one wheel to another likely fix it? Looks like new freehubs are only €11.

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Re: Free hub play
« Reply #5 on: March 06, 2019, 12:31:55 pm »
if you can buy a new freehub body that is an easy fix. However they don't all come 100% play-free from new.

I re-shim freehub bodies, and I aim to make them 'better than new' so that there is no free play at all.  I achieve this by lapping the adjusting race to the correct thickness, which means an accuracy of better than 5um. Contrast this with the minimum variation you can get with shims which might be ~50um.   However this isn't easy to do and most folk don't bother with even re-shimming freehub bodies, leave alone lapping the parts until they are perfect.

Shimano originally intended freehub bodies to be rebuilt, and indeed used to sell tools for this purpose. However this isn't economically viable in a bike shop so they have stopped selling the tool. You can still buy suitable tools to do the job though.

New bearings should only be required if the old ones are in any way damaged.  It won't hurt to fit better balls (eg Gr10) but new Gr25 balls may be a step backwards from used Gr25 balls; barring catastrophes the balls tend to wear themselves to better match one another.

cheers

rr

Re: Free hub play
« Reply #6 on: March 06, 2019, 01:13:58 pm »
it isn't quite normal for there to be free play in the freehub bearings which disappears when the wheel is installed.  It may indicate that bolt #9 here

https://si.shimano.com/pdfs/ev/EV-FH-M6000-4196.pdf

isn't tight.

Oh goody. To get to that I'm gonna need pull the whole thing apart. If I am going to that effort is it worth replacing bearings at the same time?

Quote
If there is play in the main hub bearings when the wheel is out, which disappears when the wheel is installed and the QR is tightened, this means the hub is perfectly adjusted.

If there is play in the freehub body bearings this usually persists when the wheel is installed. It can be adjusted out by re-shimming the freehub body.

Just checked, and there is play in the cassette/freehub when it's installed in the bike, but no play in the wheel. How does one re-shim the freehub body?

Looks like the freehub is Y3SW98060, which I think is the same as the freehub body on my spare wheels.

Would swapping the freehub from one wheel to another likely fix it? Looks like new freehubs are only €11.

J
That bolt takes a 10mm Allen key, be very careful putting it back together, it is a fine tread on a steel bolt into an alloy hub. If you cross thread it it can wreck the thread and the hub. DAMHIKT.

Sent from my moto x4 using Tapatalk


Re: Free hub play
« Reply #7 on: March 06, 2019, 04:40:06 pm »
Some are a 14mm allen key, I think.
Never tell me the odds.

Re: Free hub play
« Reply #8 on: March 06, 2019, 07:35:09 pm »
that's right, but if the hub has a 10mm steel axle, the hollow bolt takes a 10mm allen key.  You can also use a 12pt spline bit, but most are not a perfect fit, because spline bits are usually a tri-square design, not a bi-hex.

cheers

quixoticgeek

  • Mostly Harmless
Re: Free hub play
« Reply #9 on: March 20, 2019, 04:18:43 pm »

It's 14mm... I just took the thing apart, and realised I don't have a 14mm allen key. Have ordered one. I've also discovered that the freehub body I ordered, I've made a off by one error, and ordered Y3SW98060, rather than Y3CZ98050.

Oops.

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Re: Free hub play
« Reply #10 on: March 20, 2019, 04:58:20 pm »

I have a free hub on my wheel, it's a shimano MTB 135mm disk hub (Deore XT FH-M6000),

if the hub is FH-M6000 (as indicated upthread) then the bolt ought to be a 10mm one, Y3BL03000, which is the same as a gazillion other shimano freehubs.

If you have a 14mm bolt, do you in fact  have FH-M8000....?

cheers


quixoticgeek

  • Mostly Harmless
Re: Free hub play
« Reply #11 on: March 20, 2019, 06:30:40 pm »

I have a free hub on my wheel, it's a shimano MTB 135mm disk hub (Deore XT FH-M6000),

if the hub is FH-M6000 (as indicated upthread) then the bolt ought to be a 10mm one, Y3BL03000, which is the same as a gazillion other shimano freehubs.

If you have a 14mm bolt, do you in fact  have FH-M8000....?

cheers

Yep. M8000. Seems I had either read it wrong, or transposed it wrong somewhere. Which is a shame, as I bought 2x freehub bodies for an FH-6000...

Fortunately, I do have 2 hubs on other wheels that it will fit on...

Have now ordered the correct part, should arrive tomorrow.

J
--
Beer, bikes, and backpacking
http://b.42q.eu/