Author Topic: Lazy pawls?  (Read 678 times)

Lazy pawls?
« on: 03 June, 2022, 07:03:49 pm »
On today's ride, the Elan produced a subtle but weird problem. As I pedal it feels like slack gets into the transmission which then subtly clunks under the power stroke. I've had a 'wiggle' and I can't see anything loose on the pedals, crank, cleats, chain-rings, spokes etc. I'll take the cassette off and check the freehub and for divots. That would create some play which could 'clonk'. But if it isn't that then it might be the pawls - almost like they are too slow to flick back into catch. Is that such a thing?

Am I barking up the wrong tree? Is there anything else I might be missing?


BFC

  • ACME Wheelwright
Re: Lazy pawls?
« Reply #1 on: 03 June, 2022, 07:50:34 pm »
Probable cause is the freewheel pawls, two common causes are:

Grease is a bit too thick and chewy - tends to be a problem on re-greased or serviced freehubs - too much grease in the wrong places but this settles, or with mature freehubs which can be temporarily fixed with solvents/oils.

Corroded fiddly bits in the freewheel are more terminal - non stainless tiny springs fail and have to be thrown away.

Re: Lazy pawls?
« Reply #2 on: 03 June, 2022, 07:58:55 pm »
I had this problem when I serviced some Dura Ace hubs and used too much grease.  On a very cold ride shortly after the pawls stopped returning so the freewheel wouldn't engage at all.  Ride abandoned  ::-)

Since then I mix Wahl clipper oil with a thinner grease on the pawls and this seems to work well - at all temperatures!
The sound of one pannier flapping

Re: Lazy pawls?
« Reply #3 on: 03 June, 2022, 09:11:39 pm »
I've had pawl springs fail. Luckily, I've managed to get replacements. Not always possible.

Re: Lazy pawls?
« Reply #4 on: 04 June, 2022, 09:02:14 am »
Thanks all - reading up on t'internet, this seems quite a common failure mode for my Shimano hub (cheaper RX010 wheelset). It goes quiet, the chain gets slacker, and eventually it fails to engage.

SJS have a replacement freehub for a decent price. They are easy to fit so I've ordered that.

Might be time to invest in some nicer wheels... although I hate noisy freehubs, which might limit the selection.

BFC

  • ACME Wheelwright
Re: Lazy pawls?
« Reply #5 on: 04 June, 2022, 11:53:52 am »
I have serviced a shimano freehub in the past - it is possible but extremely fiddly, done more to confirm suspicions on the failure mode. The pawl was sticking in old dried up grease, and entered into permanent freewheel mode on a chilly ride, seals and bearings were in good condition. Rebuilt unit is in the spares box.

If new parts are available buy them. Taking old ones apart is an interesting experiment for an adventurous mechanic, if any sub components have failed they are not available, and they are a real pain to re assemble. Also really needs an old hub to bolt them onto and mount in a vice.

If there is significant play between freehub and the hub, usually with brown residue, the bearings are shot due to water ingress. Once the bearings develop play the seals cannot be salvaged or replaced. I have seen a few shimano style bolt on freehubs that have died this way.

Re: Lazy pawls?
« Reply #6 on: 04 June, 2022, 01:02:11 pm »
Exactly my thinking. I watched youtube video's last night. As you say, it is straightforward, but fiddly. A new freehub is a reasonable cost, and easy to replace.

It will be interesting to see if there is an obvious problem. It's only done 3000 miles, although it is a cheap wheelset (Shimano RX010) and I ride in all weathers along lanes/byway/canal/forest paths etc.

BFC

  • ACME Wheelwright
Re: Lazy pawls?
« Reply #7 on: 04 June, 2022, 06:52:08 pm »
To analyse a dead freehub (shimano or a copy of)...

Making a tool (a bit of suitably stiff metal) to engage in the slots in the collar - that hides beneath the drive side cup and the seal that pops out - is the key to getting these things apart, whilst the freehub is firmly attached to a hub.

I can't remember what I used/did, but the collar was not that tight on a late 90's ultegra freehub. I suspect I made something from a piece of stainless steel I had in stock or a "spanner" for one of the angle or die grinders turned by an adjustable spanner. Try both directions - it may be a left hand thread.

If there is brown crap in the bearings when you take the axle out, don't waste your life going any further (if spare freehubs are available).

Re: Lazy pawls?
« Reply #8 on: 05 June, 2022, 11:55:17 am »
I had the exact same problem as BFC and took the same action, replacing the freehub and rebuilding the old one which is now kept as a spare.  I tried to "drift" the cone/race nut (it has a reverse thread) with a screwdriver in the notch but couldn't budge it, so I bought a tool from ebay - only about £8 - and it did the job nicely.

https://www.ebay.co.uk/itm/224522195238




Re: Lazy pawls?
« Reply #9 on: 05 June, 2022, 12:05:16 pm »
I now use semi-fluid grease on my drive side hub bearings.  To apply it, I use a hair dye bottle but I later saw an identical bottle for sale cheaper at Wiggle - sold as "The Joe's No Flats Applicator Bottle is specifically designed for use with tyre sealant".  It really is the same bottle except for the name printed on the side.

https://www.wiggle.co.uk/joes-no-flats-applicator-bottle