Compatibility of Shimano freehubs.

General cycling advice ( NOT technical ! )
ANTONISH
Posts: 1654
Joined: 26 Mar 2009, 9:49am

Compatibility of Shimano freehubs.

Postby ANTONISH » 15 May 2015, 11:18am

Is there a site where such information is available?
Some time ago I changed a 7 sp shimano freehub from a deore lx hub with a 9/10 sp freehub from a damaged RS20 wheel.
It works ok and I want to repeat the exercise with a 105 hub - but there seems to be a wide range of these items and I'm not sure what ones ( if any ) will be suitable.

Brucey
Posts: 37415
Joined: 4 Jan 2012, 6:25pm

Re: Compatibility of Shimano freehubs.

Postby Brucey » 15 May 2015, 12:21pm

you need to say which model of 105 hub you have really. There are lots.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

ANTONISH
Posts: 1654
Joined: 26 Mar 2009, 9:49am

Re: Compatibility of Shimano freehubs.

Postby ANTONISH » 15 May 2015, 4:44pm

FH-1055 Brucey. Any information gratefully received.

Brucey
Posts: 37415
Joined: 4 Jan 2012, 6:25pm

Re: Compatibility of Shimano freehubs.

Postby Brucey » 15 May 2015, 5:46pm

this pic

Image

from

http://forum.ctc.org.uk/viewtopic.php?f=5&t=96294&sid=086df405032b39b502d57a4c3a7d1fe4

shows the correct style of body fitting, bottom right.

I think that this one

http://www.sjscycles.co.uk/shimano-deore-lx-fh-t660-cassette-freehub-body-3d6-9804-prod31406/

will fit the hubshell (although I don't think you will need the washer) convert to 8/9s and will accept the FH-1055 RH cone seal. You will need a spacer on the RHS. There are other bodies that will fit but the LX one has a seal in the back, which not all the others do.

Actually I quite like keeping the 7s body, to which you can fit 8 from 9 of a 9s cassette, and have a stronger rear wheel with less dish.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

ANTONISH
Posts: 1654
Joined: 26 Mar 2009, 9:49am

Re: Compatibility of Shimano freehubs.

Postby ANTONISH » 16 May 2015, 5:25pm

Thanks for that Brucey - as always a font of knowledge - I must have just got lucky the first time.
I'm trying to "standardise" on 9's so that I can swap wheels if I want to .
I take your point about 8s on a 7 body giving a stronger wheel. The hub in question already has an 8 from 9 on it in fact.

Brucey
Posts: 37415
Joined: 4 Jan 2012, 6:25pm

Re: Compatibility of Shimano freehubs.

Postby Brucey » 17 May 2015, 8:03am

the body fitting on those hubs (as per the RHS ones in the photo above) is the most common type that has been used on freehubs. In fact (barring Dura-Ace and one or two others which have used oddball variants) it was the original type used on the first shimano freehubs even before they used a bolt to secure them. You can even use the freehub body from a non-bolt secured freehub on a later bolt-secured hubshell. Some (MTB ones mostly) have a backing washer in the hubshell but the freehub body spline can still be similar, even if the freehub body has a seal on the left end.

The RH bearing seal varies with all such hubs though and this is a major source of incompatibility. Swapping RH seals round is a bit of a pain.

In recent years there have been more variations in body spline design; the RM series have mostly used the bottom left style spline, paired with a standard bolt and axle. The top left spline style has appeared in various more recent freehub designs, but I'm dashed if I can see any pattern to it. Recent RM series hubs, and various road /offroad hubs have had this fitting; it exists in at least two distinct styles, with different sized bolts up the middle to match different axle diameters.

I do not believe that there is a definitive list of compatible hubs/bodies. Shimano used to publish a list but the list was incomplete, and they deleted it from their website a few years ago.

When investigating compatibility, a very useful method is to look on SJS because they show photos of both ends of each end of every spare freehub body they sell.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

ANTONISH
Posts: 1654
Joined: 26 Mar 2009, 9:49am

Re: Compatibility of Shimano freehubs.

Postby ANTONISH » 17 May 2015, 1:05pm

Thank you again for the info Brucey.
I sometimes think that manufacturers like to have a little confusion around their products.

Cyckelgalen
Posts: 22
Joined: 21 Sep 2018, 11:29am

Re: Compatibility of Shimano freehubs.

Postby Cyckelgalen » 14 Feb 2020, 11:21am

I have failed to find so far a decent freehub compatibility chart to see clearly which freehubs match various hubs.

I wonder if is necessary taking a freehub spare on an extended tour outside Europe, given the frecuent reports of newer freehubs failing. If so, I'd need to find a freehub compatible with different hubs.

We use an XT FH-M756A and a new generation alu-axel XT FH-M758. Different free hubs with different part numbers are listed by Shimano for these two hubs, y3sw98060 and y3tg98030, but that may not necessarily mean that they are not interchangeable. Sometimes parts have different numbers because of cosmetic variations, different materials, seal quality etc, but are functionally identical. Actually the M756 freehub is compatible with the M5XX Deore hubs, I believe .

Anyone knows these two freehubs in question or a good compatibility chart on the issue ?

Thanks.

Brucey
Posts: 37415
Joined: 4 Jan 2012, 6:25pm

Re: Compatibility of Shimano freehubs.

Postby Brucey » 14 Feb 2020, 11:52am

those hubs definitely use different freehub bodies for the (very simple) reason that they have a different sized hole up the middle.

I would suggest that for touring, using shimano freehubs with 10mm steel axles is probably best; these usually have a hub fitting which is common to the greatest number of other shimano freehubs. FH-M756 uses this most common fitting.

If you look at SJS's page of shimano freehub spares there are dozens of them. Well, IME, about half of them will fit to hubshells like the FH-M756 one (with the 'original' pastrycutter interface) and the differences between these freehub bodies mainly reside in the seals in the RH end. These seals can easily be replaced with the correct/alternative one, or in an emergency, left out altogether, so if you use the most common type of hub, you are most likely to be able to effect a repair in the event of problems.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Cyckelgalen
Posts: 22
Joined: 21 Sep 2018, 11:29am

Re: Compatibility of Shimano freehubs.

Postby Cyckelgalen » 14 Feb 2020, 12:11pm

Thanks Brucey,

I should have thought of that! The aluminium axels have thicker walls and large outer diameter than the older steel XT's, so the freehubs have to be different. The hollow fixing bolts use 10 vs 14 mm Allen wrenches.
Bad news, the wheel came on a bike that was a very good deal otherwise, but I would never have chosen a new XT alu-axel hub for touring. I even find the adjustment with the Allen locknut cap more difficult that the good old two 17 mm nuts.
If I may ask you Brucey, are these M785 hubs really more prone to failure that the older ones? Many high end world touring bikes have these hubs now, The only improvement I can see is that the RHS cone, the one that most frecuently works loose, is fixed to tne axel.

Brucey
Posts: 37415
Joined: 4 Jan 2012, 6:25pm

Re: Compatibility of Shimano freehubs.

Postby Brucey » 14 Feb 2020, 1:02pm

the bearings are certainly not as strong in the M758 hubs, and I agree the adjustment method is in no way an improvement over simpler designs; a combination of these things means that reports of bearings going bad in these hubs are more common than you might otherwise expect. A design/manufacturing flaw made the first shimano freehubs with the fatter axles prone to failure. This problem was so bad that many MTBers said 'shimano hubs? never again'. They have improved matters since then but I still think they are not as reliable as other freehub designs; the problem is that (especially if there is any free play in the freehub bearings) the pawls see a skew load, and the 'ear' on the end of the pawl can break off. The 'ear' is there to allow the return spring to work correctly. Bits of metal floating round the freehub will inevitably cause trouble. XT hubs of this sort usually have four large pawls (for 2/4 engagement), so the whole thing ought to be far stronger than the old design, but in practice it isn't. Similar 'road' freehubs have just two similar pawls (for 2/2 engagement I think) and these don't seem to fail in the same way, possibly because they see lower torques than in MTBing. Touring torque is of course more like MTB torque.

FH-M756A is made more cheaply than FH-M756 was and there have been reports of failures with those hubs too, possibly an isolated QA problem.

FWIW with any freewheel or freehub I would always

a) make sure there was no free play in the bearings and
b) only go on tour with a well-used (rather than brand new) setup.

The reason for b) is that most freewheel mechanisms (all freehubs probably) are designed to engage both pawls at once and if this doesn't happen, the mechanism sees abnormally high loads which can result in premature failure. However manufacturing tolerances mean that new mechanisms are not usually 'perfect' and one pawl clicks before the other. If you are unlucky enough to 'hit the gap' you are doubling the loads on that single pawl. However after a period of use because of wear on the favoured pawl, this situation usually improves.

If you turn the wheel very slowly forwards and listen carefully, you can hear if the pawls are properly synchronised or not. The best mechanisms go 'clickkk' as both pawls engage, no matter how slowly you turn the wheel. However it is far more common to hear two distinct clicks in a new mechanism. In four-pawl freehub bodies (eg the XT 758 ones) there will be two different alternating types of click as 2/4 pawls engage. These freehubs will probably take much longer to 'run in' if there is any significant error, because the wearing areas are both larger and more numerous.

'Twas ever thus; BITD seasoned racers would only use a well proven freewheel body for critical events, such were the chances of newer ones developing problems.

Note also that if the outer part of the freehub body is even slightly eccentric, no amount of running in will ever make it perfect. You can tell if this is the case if the 'click-click' pattern varies systematically with the wheel position when you turn the wheel slowly as described above.

hth

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Cyckelgalen
Posts: 22
Joined: 21 Sep 2018, 11:29am

Re: Compatibility of Shimano freehubs.

Postby Cyckelgalen » 14 Feb 2020, 2:18pm

Thanks Brucey! Great piece of advice!

Ideally one should strip the freehub to have a look for abnormal wear. That sort of unbalanced engagement and load should leave visible wear traces, but doing that is such a faff.
Short of replacing the hub (not an economical option these days, rather get a new wheel), I will simply get rid of all play at the freehub bearing to decrease those risks, there is some play in all my hubs, and try to keep the mechanism well lubed.
The M785 has almost 3K miles and should ok, well worn in. The M756A is new, but impossible to know if it is one of the earliest, less reliable batches. It has been around for ages but they can be stocked for years by suppliers.
On taking away all play, doesn't the quick release have any compression effect on this adjustment as it has on the axel C&C bearings?

Brucey
Posts: 37415
Joined: 4 Jan 2012, 6:25pm

Re: Compatibility of Shimano freehubs.

Postby Brucey » 14 Feb 2020, 7:49pm

If the QR affects the freehub bearings in a shimano freehub, it means the main hub bearings are badly adjusted and under massive unnecessary load from the QR. In practice when setting up the freehub bearings, you don't need to worry about QR loads. Just be aware that it is a matter of trail and error, and you need to be consistent about tightening the cup/lockring/cone on it's LH thread, else you may get a false reading.

When adjusting a freehub, often the shims don't allow fine enough adjustment; in this case you can grind or lap the bedding face of the lockring. You can get within 10um (or better) this way, c.f. the thinnest shim which is 50um thickness.

If you don't have the correct shims, you can make them (with great care) using scissors and beer can.

Tip: if using a very thin shim, best to have it sandwiched between two thicker shims; if on the top of the stack, it may be torn or damaged more easily as you tighten the lockring.

FWIW measuring/inspecting parts is unlikely to tell you much unless they are actually broken; it is both easiest and best to listen to the pawls if you want to know if they are properly synchronised or not. If you do dismantle a good freehub body, it is important that the pawls are each returned to their original location; other arrangements usually result in the pawls becoming unsynchronised again.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~