Freehub a bit too free - not engaging - options

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LittleGreyCat
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Freehub a bit too free - not engaging - options

Postby LittleGreyCat » 13 Aug 2017, 4:18pm

First a bit of history.

I have a Dawes Galaxy which is half way through fettling and has been for a long time.

Things already bought; cartridge bottom bracket, new chain, new large chain ring.

Although it worked last time I rode the bike, the freehub spins in both directions.
I have squirted some WD40 in there and that frees things off for a bit but someone advised me that it would be advisable to replace it.

Firstly, is a freehub with sticky innards destined for the bin?

If so, I seem to have multiple options.

    Replace it with another 7 speed freehub (if I can find one) and use the existing cassette
    As above but replace the cassette at the same time
    Fit an 8 speed freehub and cassette and a new derailleur (if required)

I have STI gear levers which I assume would handle an 8 speed cassette.
I am assuming I would need a new derailleur to get the extra gear.
I don't know if I need extra space in the frame for the extra gear.

Final thing, three front rings 52/42/30 and the 7 speed rear cassette is 12/28 (which I assume is road bike gearing).
Given that I sometimes get very close to the "granny" on my MTB with road tyres on my regular rides, should I consider a different set of gearing?

Sigh.
I started out replacing the chain and............ :shock:

Keezx
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Location: The Netherlands

Re: Freehub a bit too free - not engaging - options

Postby Keezx » 13 Aug 2017, 4:51pm

I would bin a non-working Shimano freehub.
Not worth the trouble of taking it apart and messing with tiny pawls and bearing balls.

fatboy
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Re: Freehub a bit too free - not engaging - options

Postby fatboy » 13 Aug 2017, 5:01pm

What hub is it? SJS cycles do at least one 7 speed freehub. I'd try and stick with 7 as getting an extra gear can quickly get expensive!
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gaz
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Re: Freehub a bit too free - not engaging - options

Postby gaz » 13 Aug 2017, 5:04pm

There are a variety of fittings between Shimano freehubs and the hub itself. I'll see if I can dig up some relevant threads.

Do you know the model number (FH-xxxx) for your hub? Is the hub 130 or 135 OLN?

A 7 speed rear mech will work fine on 8 speed. 7 speed index shifters will not shift an 8 speed cassette (8 will usually shift 7, so if you already have 8 no problems) although they'd be fine for a 7 from 8. 7 speed cassettes are still available and will fit an 8 speed freehub when used with a spacer.

Try this thread for freehub servicing.
viewtopic.php?f=5&t=115327
These for different types of freehub/hub fitting.
viewtopic.php?f=1&t=96825
viewtopic.php?f=5&t=113087
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531colin
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Re: Freehub a bit too free - not engaging - options

Postby 531colin » 13 Aug 2017, 5:16pm

8 speed STIs will do 7 gears, with a "click" left over......but 7 speed STIs won't do 8.
8 speed cassette/freehub is bigger than 7 speed by 1 sprocket and spacer, about 5 or 6mm.
You can put a 7 speed cassette and a spacer on an 8 speed freehub, if you want.......you can't put an 8 speed cassette on a 7 speed freehub unless you remove one sprocket/spacer.
If you swap 7 & 8 speed freehubs, you will have to re-dish the wheel, because you will change the hub width.
The gap between the rear dropouts must match the hub width reasonably well....it would be worth measuring your hub & frame, they could be 126, 130, or 135mm.
You may struggle to find a freehub that fits your hub.....of any speeds!

All in all, my approach would be to flood the freehub with something like WD40 or any other thin oily aerosoly thing, and then flood it with oil. That should fix a gummed-up freehub, but not necessarily a rusty one. Then re-grease the hub bearings.
Cross-posted with Gaz....as he says, the mech. is likely to be the least trouble!

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Gattonero
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Re: Freehub a bit too free - not engaging - options

Postby Gattonero » 13 Aug 2017, 5:38pm

Keezx wrote:I would bin a non-working Shimano freehub.
Not worth the trouble of taking it apart and messing with tiny pawls and bearing balls.


The thing is, tooling for repairing a Shimano freehub is hard to find and does cost money. And it may well be like flogging a dead horse.
Given that a faulty freehub can leave you stranded in the middle of nowhere, or to completely ruin your trip if a competent bike shop is not on hand, I'd say that £15 is money well spent for peace of mind and many miles to come.
I do have access to the specific tooling, and I've done this type of repair many times. But I won't recommend it to most, because it does need the tooling, the knowledge of how to do it, and a few donor freehubs for a replacement pawl, or spring, or outer ring, etc.
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Brucey
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Re: Freehub a bit too free - not engaging - options

Postby Brucey » 13 Aug 2017, 7:20pm

there are two pawls inside a shimano freehub and commonly they become stiff to work if the freehub is allowed to get water in or run without lube for too long. Often the problem is dried grease; spraying WD40 provides temporary relief because it softens the dried sticky grease for as long as it takes the dried grease to absorb the WD40. You need something else in there really.

My advice; run some oil (preferably ATF) in from the RH end and just use the bike. After a week or so of riding it a few miles each day, (add more oil as required; dirty stuff will come out on the side nearest the spokes) assess the condition of the freehub. If you can hear two pawls clicking away (wheel the bike very slowly forwards; there are ~eighteen ratchet teeth, and two pawls that are meant to engage at the same time; go slow enough and you will usually hear the two pawls separately). If the clicking is healthy and the wear in the bearings isn't too bad then you will almost certainly get some more use out of it.

The chances are that before the thing started to freewheel in both directions, it had only one working pawl for a while anyway.

If the freehub is a bit knackered, you can rebuild it or replace it. Last time I looked SJS still stocked a 7s freehub that (with a little fiddling) will fit most 7s shimano hubs (apart from some of the RM-series). You can fit 8 from a 9s cassette onto a 7s freehub body, and a small tweak to the rear mech pinch bolt gets the indexing to work with 8s shifters even though the sprocket pitch is different. I favour a 7s freehub for a touring bike because you can still have a wide gear range and a 7s/135mm rear hub (as Dawes fitted for a while) build into the strongest (standard) wheel for touring purposes.

If you want me to, I will rebuild your freehub body BTW.

hth

cheers
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LittleGreyCat
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Re: Freehub a bit too free - not engaging - options

Postby LittleGreyCat » 13 Aug 2017, 9:12pm

Brucey, thanks.

Others also many thanks.

I will read this again in the morning (my current impression is that the easiest thing to do is see if it will free off with plenty of lubrication).

Can I check what ATF is, please?

I recognise it as a TLA for Automatic Transmission Fluid (which used to be well known for stripping paintwork) but does it mean something else in this context?

Brucey
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Re: Freehub a bit too free - not engaging - options

Postby Brucey » 13 Aug 2017, 9:25pm

ATF = Automatic transmission fluid

not noticed it taking paint off; brake fluid and antifreeze do that well enough though...

cheers
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drossall
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Re: Freehub a bit too free - not engaging - options

Postby drossall » 13 Aug 2017, 10:32pm

Gattonero wrote:The thing is, tooling for repairing a Shimano freehub is hard to find and does cost money. And it may well be like flogging a dead horse.

Following advice from Brucey and others in Another Place, I've just bought a tool for stripping freehubs for less than £7. But I'm interested to see inside mine, I've already got a spare freehub in stock, and I like flogging dead horses :lol:

I'll let you know how I get on.

reohn2
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Re: Freehub a bit too free - not engaging - options

Postby reohn2 » 13 Aug 2017, 10:56pm

FWIW,I think I may have a 7sp freehub in "the box" if the OP wants it :)
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LittleGreyCat
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Re: Freehub a bit too free - not engaging - options

Postby LittleGreyCat » 14 Aug 2017, 8:00pm

Just been spinning it and the bearings feel a bit rough.
The dust covers say Sachs.

Even more stripping down in store; if the rear hub is shot at then the minimum is a wheel build with a new hub but I'm rapidly approaching the point when all that is left is a worn alloy rim and a very aged tyre.

New wheel, freehub and cassette is beginning to look like a possible cheaper option.

How do I tell what shifters I have and what they are capable of?
Looking back, I probably bought them around 2008/2009 to suit the 7 speed setup but I don't really understand these shifters built into the brakes on drop bars.
With the normal indexed shifters you have an indicator for which gear you are in but these just seem to click sideways for up and down.
Do they just keep clicking until the derailleur says enough?

Whatever, I think I will keep the frame even if everything else evaporates.

Edited to note that I am very touched by the generous offers of help and bits.

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gaz
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Re: Freehub a bit too free - not engaging - options

Postby gaz » 14 Aug 2017, 8:13pm

LittleGreyCat wrote:Just been spinning it and the bearings feel a bit rough.
The dust covers say Sachs.

Are you sure it's a freehub? Sachs did make these but they also made both threaded and helicomatic freewheels. Pics will help if you have any doubts.
LittleGreyCat wrote:How do I tell what shifters I have and what they are capable of?

IIRC if you roll the covers on the hoods forward (as if to fit bar tape) you'll discover the model number, ST-xxxx. Post that for more info.
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Brucey
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Re: Freehub a bit too free - not engaging - options

Postby Brucey » 14 Aug 2017, 8:15pm

Sachs were taken over by SRAM nearly twenty years ago. SRAM sold parts with Sachs branding on (including 7s freehubs, although they are not commonplace) for a while until they ran out of stock. However is it possible that you are looking at the cassette not the hub itself? If it is a Sachs hub (rather than just a Sachs cassette) freehub spares will not be easy to find. It can still be rebuilt though.

Anyway the freehub bearings don't really matter that much; they only turn when they are not under load, and they are only under load when they are not turning. My advice re oil flushing and use of the freehub stands, but if the rest of the wheel is knackered, a replacement doesn't seem like a bad idea...

cheers
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531colin
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Re: Freehub a bit too free - not engaging - options

Postby 531colin » 14 Aug 2017, 8:21pm

LittleGreyCat wrote:...........
With the normal indexed shifters you have an indicator for which gear you are in but these just seem to click sideways for up and down.
Do they just keep clicking until the derailleur says enough?......


No, its the lever thats the clever bit, the derailleur just does what its told.
The lever has a set number of clicks. Free the cable from the derailleur either literally by undoing the pinch bolt, or functionally by taking the gear cable outer out of the slotted stop on the chainstay....if indeed it is slotted.
Then, holding the bare inner cable next to the down tube, you can "count the clicks" going from one end of the movement to the other.
6 clicks = 7 positions, of course!

....i think I still have the tool to remove Sachs (Neos?) freehubs....instructions in French, naturally!