Cycling UK Forum

I'm restoring, slowly, a 1953 Raleigh Lenton Sports which has a front dynohub. Now I'm not very familiar with them, somewhere between my loosening the connector nuts on the hub so i could take the wheel off to put it in the car and the next day, the bolt fell off and with it, it seems, the protruding bit from the hub. My question is, does this normally come out? I'd remove the other one and look but not certain that's ok and I'd ever be able to put it back! To help me look for it, am I looking for a short bolt with no head? If I can't find it (very possible) is there any way i can replace it?

Pic below will hopefully paint a thousand words. Thanks all!

AFAIK, the contact is not just screwed into its place. So you probably have to remove the rivets from the insripted plate, replace the bolt and fit new rivets afterwards. DON'T DO THIS!

You're a bit in a trouble there as you mustn't remove the magnet (which is housed in the aluminum ring with those four D-headed bolts) from the armature (housed behind the aluminum plate with the inscriptions and the contacts) without a suitable keeper ring. Otherwise the 20 pole alnico magnet will lose most of its magnetism. The inner plate will not go through the outer aluminum housing, so you cannot remove it without taking the magnet off the armature. So you either have to search for the keeper or you have to replace the magnet with a new one (there are a few people who put 20 neodymium magnets into their dynohubs). I'd prefer the first solution, good luck in finding a keeper.

Thanks Hein, Is it alright if I just had a little cry? I did not expect it to be that hideous but not completely surprised either. I wasn't sure about reinstating the lighting, in the unlikely event I rode it at night I'd probably want something a bit more effective. It would be nice to be complete but with it being a drop bar model it seems a little less essential than on a Superbe or something. MAybe it'll just have to be ornamental, I don't fancy the alternative!

All may not be lost! This page:

https://hadland.files.wordpress.com/2012/07/sagh6.pdf

has exploded views and servicing instructions.

The warnings above about not separating the magnet and armature are quite right - don't be tempted to ignore them! However, by removing the magnet retaining screws, washers and nuts, GL612, GL333, GL316, (and the axle / cones) the whole armature and magnet assembly can be removed complete. You need to be careful here, but the magnetism does tend to hold them together - you need to give a deliberate press to separate them. You might want to tie-wrap them together at this stage. Once removed you may be able to see how to refit your missing screw etc. - I can't vouch for this last bit as I haven't done it myself and the only dissassembled one I have isn't with me at the moment (I can have a look at it next week if needs be).

It seems as though you've nothing to lose by trying this. In the worst case you'll put it back together and have a non-working (electrically) hub, just like you have at the moment!

something horrible has happened there for sure.

There is normally a captive bolt held in by the small 'tufnol' plate. I can only suppose that this has been pulled out or (somehow) has dropped inside (although the latter may in fact not be possible in most cases). The bolt is hollow and has a square head on the back. The wire is soldered directly into the hollow back. The AF size of the square is only a little larger than the clearance drill size of the thread, so you can see how it could pull right through; if there are marks in the hole through the tufnol plate this is probably what has happened.

Fixing it? Gah.

You need to remove the tufnol plate (one rivet) and/or the whole cover plate (two rivets) by drilling out the rivets. Then you will find that the copper winding is about the thickness of a human hair and has a shellac coating on it; working in a tiny hole you have to strip the shellac coating and remake the solder connection onto the back of the hollow bolt. Not easy; not at all easy....

The good news (the only good news...) is that you don't need to separate the magnet and the armature in order to do any of this. If you take it apart, do take pics and post them; I'm sure there will be interest in this.

cheers

Thank you all, I may say "stuff it!" and take it apart for the experience, but I don't hold out a lot of hope! I will take pictures if I do. I think it's the "thickness of a human hair" that strikes the most fear, though there is plenty of competition! I really don't know how it could have happened either, sounds like some force would be needed. Weird. And annoying!

If fixing your existing item proves too difficult you could always transfer the magnet and armature assembly from another hub into your shell (assuming that you want your existing shell/wheel kept as they are). Replacement hubs are fairly easy to find (cycle jumbles, online auctions etc) for a few pounds.

I wasn't sure about reinstating the lighting, in the unlikely event I rode it at night I'd probably want something a bit more effective.

The electrical output of these hubs, about 2Watts, is sufficient to drive many modern LED lights. I have a roadster with a combined gear and dyno hub, the output of which is slightly less than your GH6, and it drives Busch and Muller LEDs. The B and M innards are housed inside a Sturmey Archer front lamp, so the original appearance has been largely retained.

It's impressive really isn't it, mine's 60-odds years old and capable of running efficient new lighting. Power is power i suppose, but I still think it's cool. And keeping it period looking is the icing on the cake!

Does it happily run front and rear of modern lights?

If they are LED lights, yes, it does.

[XAP]Bob wrote:Does it happily run front and rear of modern lights?

Mine runs a B&M D'lumotec front and a Seculite rear. A family member has the same combination running from a Shimano dynohub. The Shimano version illuminates at slower speeds (just above walking pace) and maybe a bit brighter when going faster. However, as stated above, my SA hub is combined with a hub gear and provides a little less power compared the front dynohub (1.8W as opposed to 2W if I remember correctly).