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AW axle bolts keep coming loose

Posted: 5 Sep 2020, 3:51pm
by jb
Anybody else had problems with the wheel nuts on an AW hub coming loose?

I've made a bespoke axle lock to prevent any turning movement but still they loosen off after hefty climbing and long rides.

Re: AW axle bolts keep coming loose

Posted: 5 Sep 2020, 4:33pm
by fausto99
No. Never - and I've got a very iffy setup with the hybrid gearing on my Mk 1 Moulton. I use the longest available axle to get past the 6 gear extended 5 speed freewheel and still only get the nut on 3 or 4 turns; never the full depth. I can't risk the extra depth of a washer either! It's never come loose on its own.

Re: AW axle bolts keep coming loose

Posted: 5 Sep 2020, 4:56pm
by robc02
Does your bespoke axle lock replace the standard no turn washers? If so, how does it fit?

You probably already know this, but the standard no turn washers are fitted to both ends of the axle. If the axle is only restrained at one end it may be flexible enough to twist slightly under heavy load.

It does sound as though the axle is managing to turn under load.

Re: AW axle bolts keep coming loose

Posted: 5 Sep 2020, 7:12pm
by jb
It has the standard pressed steel Strurmey Archer non turn washers at the non drive side & my homemade one at the other.

The one I made is a perfect fit to prevent movement and is bolted to the derailleur hanger. It also has a bolt to prevent the chain pulling it forward.

One would have thought that the axle was fairly well captive between the two.

Re: AW axle bolts keep coming loose

Posted: 5 Sep 2020, 8:23pm
by Brucey
If you are going to have just one really good lockwasher it should be on the left side of an SA AW, since the axle is stiffer left of the sun pinion than to the right.

For the lockwasher setup to work there are four requirements

a) that the axle fits the dropout OR that there are two tangs on the lockwashers
b) that the tangs fit the dropout
c) that the axle flats are a snug fit in the lockwasher
d) that the load is shared between sides

There is no such thing as 'a standard SA lockwasher'; they make about a dozen different sorts. In most installations the high gear torque is not so high that the axle requires positive restraint, so the usual thing is that the axle rotates backwards in gear 1 and then stays there. However if the axle is not a good fit such that the reaction torque causes the axle to sit lower in the dropout slot than normal in low gear, the axle will move around between gear 1 and gear 2 let alone gear 1 and gear 3.

SA lockwashers have various issues;

- standard powder met ones (with two tangs) fit well but crack too easily
- thin wrought steel ones are a bit flimsy
- single tang powder met ones are more robust (because they are thicker but can still crack
- thicker wrought steel ones don't always fit the axle perfectly
- 3/8" sized ones fit RX series 3s hubs only

So if you want a robust setup then using up to four HMW518 washers on an AW 3s hub is possible; you can use two each side, one inside the dropout , one outside, with the tangs facing in opposite directions, or shortened and facing in the same direction.

Image

being wrought material they won't break easily and can easily be modified to fit most frames.

cheers

Re: AW axle bolts keep coming loose

Posted: 5 Sep 2020, 10:06pm
by jb
Thanks for that Brucey,
I think I may have to make another bespoke non turn plate for the non drive side. The problem with the standard ones supplied was that there was no room left for chain tensioning. I think the dropout slots are shorter than normal on this frame.

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 12:41am
by Sid Aluminium
jb wrote:Anybody else had problems with the wheel nuts on an AW hub coming loose?


Constantly...until I replaced the HMW155s with HMW494s.

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 1:30am
by mjr
I've had one nut fail to stay tight shortly before it stripped its thread under minimal force. Old nut, came with the bike, probably corroded. Beware!

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 8:01am
by Brucey
Sid Aluminium wrote:
jb wrote:Anybody else had problems with the wheel nuts on an AW hub coming loose?


Constantly...until I replaced the HMW155s with HMW494s.


Image
HMW155

Image
HMW494

these powder met lockwashers score well on point c) above and the different widths of tang allow a better fit re point b)

cheers

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 8:20am
by jb
Thanks for all the replies folks, the problem would seem to be a badly fitting anti-turn washer on the non drive side. I did not think the non drive side would be as important but lit ooks like it is.

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 8:42am
by fausto99
jb wrote:... I did not think the non drive side would be as important but lit ooks like it is.

I did not realize that either. It's only my drive side which is iffy. The ND side has full nut engagement and the Mk 1 Moulton dropouts are quite long.

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 8:50am
by Brucey
if the setup has a really good lockwasher on the RHS and a bad one on the LHS, this can provoke premature axle failure, because the slotted part of the axle is subject to the worst twisting loads.

cheers

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 9:01am
by jb
Double post

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 9:06am
by Brucey
jb wrote:Double post


I didn't mention axle breakage previously, only stiffness.

Re: AW axle bolts keep coming loose

Posted: 6 Sep 2020, 9:18am
by jb
Brucey wrote:if the setup has a really good lockwasher on the RHS and a bad one on the LHS, this can provoke premature axle failure, because the slotted part of the axle is subject to the worst twisting loads.

cheers


Good point