Broken connector on SON dynamo

[thesloth]

Disaster! One of the connectors on my SON dynamo has broken off:


I suspect that the axle may not have been done up tightly enough causing the hub core to rotate. The wire then pulled against the terminal.
The connector had moved to one side: (II to I/).
I tried to move it back and it popped out.
I'm not sure if this is designed to be movable part and it can just be pushed in to place, or does it require servicing 

I had planned to be going places with this wheel in the not to distant future and so would like to make sure that it's not out of action for too long.

[simonp]

Can't help I'm afraid - bad luck.

Do SJSC do SON servicing? If not you might have to send it to Germany.

I have just bought exactly the same hub for my new bike. I wonder if the use of disc brakes makes this problem more likely.

[Kim]

Do SJSC do SON servicing? If not you might have to send it to Germany.

AIUI SJSC are how you send it back to Germany.

[thesloth]

Thanks both.
I've contacted Hunt, whom I bought the wheel from.

From what I can tell SON only receive and service standalone hubs. It needs to be removed from the wheel.
That would be ...unfortunate.

I wonder if the use of disc brakes makes this problem more likely.

Indeed. Make sure that they're done up tight!

[Oxford_Guy]

When I needed to send my Son 28 to Schmidt for servicing (via SJS)  I sent the whole wheel, this was about 5 years ago, mind

[Brucey]

you have nothing to lose by just pushing the piece back and seeing if the hub  works OK. If it doesn't, ask SJS about how to send your hub for overhaul.

Some while back I commented that the SON connector was a poor design because it wouldn't release itself very easily in the event of a fault. IIRC others may have told me that the wires pull off easily enough that this kind of damage isn't very likely.

cheers

[zigzag]

that's a right bummer!.. could the design of the hub axle be improved by making a serrated surface that meets fork ends (to prevent it moving)? if this is alteration is done (e.g. using a triangular needle file) would this void warranty?

[andrew_s]

Some while back I commented that the SON connector was a poor design because it wouldn't release itself very easily in the event of a fault. IIRC others may have told me that the wires pull off easily enough that this kind of damage isn't very likely.

Mine always pulls off easily when I forget to unplug before taking the wheel out, but it will depend on whether you put the connectors at the top, in line with the pull, or not.

For this hub, I'd expect that it will have to go back to SON, as any "fix" by just pushing the spade back in will be strictly temporary.
What is worth doing is emailing th photo to SON, asking whether it's necessary to unbuild the wheel, or whether the connection is sufficiently external to fix without opening the hub

[thesloth]

could the design of the hub axle be improved by making a serrated surface that meets fork ends (to prevent it moving)?

I did wonder about that. It's common to see that on QR hubs.

I've used SP hubs for a couple of years and IMO that connector system (similar to Shimano I believe) is far superior.

I'll probably try to bond the two spades together somehow to create a better connector. I see that others share this concern.

[andrew_s]

A thru-axle hub won't have any movement against the fork ends, or any twisting force on the hub locknuts as you tighten the axle (as can be a problem with solid axles and track nuts), so serrations won't make any difference.

I'd guess a faulty hub, and/or failure to unplug before dropping the wheel out.
I think I'll try a bit harder to remember to unplug myself.

[Samuel D]

It is surprisingly hard to remember to unplug every time you remove the wheel, especially if – like me – you sometimes use another wheel that doesn’t have a dynamo hub.

However, the plugs have always pulled off cleanly when I’ve accidentally dropped the wheel out without disconnecting. It helps that I grease the contacts.

When I unplug manually, I jiggle the top (wire end) of the plugs in a left-right arc with the hub orientated as in your photo, removing one plug at a time. This greatly reduces the force needed and risk of damage.

[jiberjaber]

A thru-axle hub won't have any movement against the fork ends, or any twisting force on the hub locknuts as you tighten the axle (as can be a problem with solid axles and track nuts), so serrations won't make any difference.

......................

Not quite understanding this, if I don't tighten my t/a front my dynamo connection rotates...

[Brucey]

a surprisingly common fault in any hub/BB that contains cartridge bearings is that a small amount of (salty) water penetrates the bearings which then seize (partially or wholly) when the bike is standing. The result is that when the bike is next used the bearing may unseize itself (usually without you knowing), or cause the bearing to try and spin wholesale where it normally shouldn't. In the latter case a hub dynamo will try (very hard) to spin in the forks.

Typical 5mm spade connectors require an insertion force vastly in excess of that required to provide a secure electrical connection on a bike, and anyway will pull off if they are tugged in one direction only.

As an aide memoir on bikes with hub generators, I usually fit the (conventional) QR skewer the wrong way round, so that the lever is 'on the wrong side' and is close to the electrical connections. This makes it more difficult to forget them when removing the wheel.

cheers

[BobScarle]

As an aide memoir on bikes with hub generators, I usually fit the (conventional) QR skewer the wrong way round, so that the lever is 'on the wrong side' and is close to the electrical connections. This makes it more difficult to forget them when removing the wheel.

That's a good tip. Going to the garage to change mine round.

[thesloth]

Hunt replied to me. They are sending a courier to collect the wheel and are going to send it to SON for servicing.
Top service from them! 

I think in future as well as making sure that the thru-axle is done up tightly I'll look at greasing the contacts. Looks like "dielectric" grease is what's needed.
...or am I overthinking it, will any old grease conduct?

[Brucey]

Vaseline will do.

cheers

[hbunnet]

As an aide memoir on bikes with hub generators, I usually fit the (conventional) QR skewer the wrong way round, so that the lever is 'on the wrong side' and is close to the electrical connections. This makes it more difficult to forget them when removing the wheel.

That's a jolly good wheeze which I will implement. Thanks Brucey.

[chrisbainbridge]

I had already swapped my QR on my hub Dynamo a few years ago. I must have got the idea by telepathy from Bruce!

[Kim]

I've got a better tip:  Secure your expensive dynamo wheel with a non-QR skewer, and put the tool end on the right side by the connectors.  You still get a reminder to unplug the cable, your wheel's slightly less likely to be nicked and the significantly better clamping force ought to help avoid the type of damage in the OP.

[andrew_s]

I used to deliberately have the QR lever at the disc brake side, so any tendency to self-unscrew was more obvious.
I'll have to check I've swapped back to undo end at the connector side now I've got Hexlox (the QR for which has anti-turn tabs on the nuts)

[thesloth]

Dynamo repaired and returned with zero cost to me by Hunt/SON after two weeks, so top marks to them both.

Interesting to see that the designed of the plastic bit that surrounds the spades seems to have changed a bit. Previously it was just circular, but now it protrudes out a bit...possibly to offer more support?

[Polar Bear]

I had already swapped my QR on my hub Dynamo a few years ago. I must have got the idea by telepathy from Bruce!

Perhaps Brucey got the tip by telepathy from you.