Chain skip after freewheeling

For discussions about bikes and equipment.
mark a.
Posts: 1349
Joined: 8 Jan 2007, 2:47pm
Location: Surrey

Re: Chain skip after freewheeling

Postby mark a. » 19 Nov 2018, 9:01am

Well the freehub is fixed. Thanks for all the help.

I managed to grab a couple of short fixing sessions in the garage yesterday. The LH seal came off OK, then a squirt of WD40 made everything clicky again. Later, once the WD40 had dried a bit, I added some oil and it's all gone back together and working.

It's not all perfect, though, since I now have cassette oscillation when freewheeling on the stand. I'll need to decide if it's not worth worrying about (I know it's common) and it might have been there before just not noticed. But I'll also check to see if I've put anything together incorrectly, perhaps there's a missing spacer somewhere.

I consider this a temporary fix until I get some proper oil for the freehub, so I might just see how the bike's doing for the next couple of weeks before taking it apart again and checking oil and grease quality.

Brucey
Posts: 32690
Joined: 4 Jan 2012, 6:25pm

Re: Chain skip after freewheeling

Postby Brucey » 19 Nov 2018, 11:45am

Deore hubs have a washer between the freehub body and the hubshell. If this is misplaced or absent then the freehub body will not run true. Another common cause of the sprockets swashing is that the last sprocket (which only goes a short way over the splines) isn't correctly installed, even if the freehub body is running true. It is easily done.

Either way I wouldn't be too keen on riding the bike if there is a fault of that kind.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

mark a.
Posts: 1349
Joined: 8 Jan 2007, 2:47pm
Location: Surrey

Re: Chain skip after freewheeling

Postby mark a. » 19 Nov 2018, 12:56pm

I've checked both, but I suppose the final sprocket being "definitely on correctly" might still not be but feel like it is. Thanks again.

Brucey
Posts: 32690
Joined: 4 Jan 2012, 6:25pm

Re: Chain skip after freewheeling

Postby Brucey » 19 Nov 2018, 2:42pm

the other thing that it might be is the shape of the teeth; a lot of sprockets have half the tooth tops on the sprockets facing one way and half the other. This can make the sprockets appear to swash even when they are running true.

Also note that the body washer often has burrs on it and may seat differently each time it is used unless it is carefully deburred.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Canuk
Posts: 1105
Joined: 4 Oct 2016, 11:43pm

Re: Chain skip after freewheeling

Postby Canuk » 19 Nov 2018, 9:10pm

I have a Mavic free hub with just this problem. A sticky, annoying hub which would jump when it felt like it. Tried all sorts, eventually I bit the bullet and soaked the whole awfully assembly in diesel for a week. The wheel had previously been stored in a warm cupboard for over a year

Runs a sweet as a nut now, WD40 on this occasion, was not my friend

Brucey
Posts: 32690
Joined: 4 Jan 2012, 6:25pm

Re: Chain skip after freewheeling

Postby Brucey » 19 Nov 2018, 9:16pm

Note that one reason for advocating ATF for this job is that it has a high detergent value; it is quite good at dissolving into dried grease and removing residues of various kinds from delicate mechanisms etc. It is these qualities (rather than its qualities as a lubricant per se) which make it good for use in sticky freehub bodies.

If you ride around with a lot of ATF in a hub for a few weeks and then strip and clean everything, you will usually find that the parts clean up rather easily. However it isn't the best long term lubricant for various reasons and it isn't good stuff to get on your skin; in this case 'avoid skin contact' is very good advice.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~