Dynamo headache

[admin]

I have a 40W E3H dynamo.
It motored but was putting out virtually no voltage.
The field coil resistance was about 3.8 OHM (vs the book value of 3.2)

Having been down this road before, I assumed armature, as that is what it was (in a similar situation) twice before.

I changed the armature.
It still motors and now puts out voltage, but only about 5v maximum (using my drill to spin it up).

I am thinking Field Coil as well.
I had an absolute bitch changing the last one - the screws only *just* came out and pushing it back in was worse.

[pete.collings]

I have changed a field coil before, the Lucas manual shows a neat expandable jack being used to push the field coil mount into position, but not having one of these most useful contraptions, I used two large bolts cut to a length such that the attached nuts could be rotated to push the mount upwards enough to start the screws. It was necessary to use some packing above the nuts, and involved some fiddling about to get it to do the job, and the replacement coil had to bend slightly to fit the inside contour of the dynamo body, but I don't remember it being a job involving a lot of cursing and swearing.
I think the screws are a BSW thread, I obtained some suitable replacements from a local stockist without too much difficulty, although that was some time ago. I also used an impact driver with a broad bit fitted to remove/replace the screws.

[keith.mettam]

Hi John,
I couldn't get my field coil screws out so, having completely mangled them, I drilled off the heads and then easily removed what was left from the field coil mounting plate with a mole wrench (they came out easily not being under tension). The field coil screws are available from feked.com the following link refers:-
http://www.feked.com/field-coil-screws.html

Funnily enough I did exactly what Pete did to install the new field coil. You do need to make sure that the coil mounting plate has plenty of pressure applied to it to get the screws fully tightened up as, again as Pete says, the new coil is curved such that it has to be compressed when fitted. If the coil is not properly home the armature may not fit back in the unit or, if it does, it may foul the field coil pole face (mounting plate). Remember to peen the screws so they can't come undone once you have assembled the unit and are happy that the armature has clearance and rotates ok.
Regards,
Keith Mettam.

[david.anderson]

John
while you have already spent money on the generator, unless you want originality I would fit an Alton. My last E3L cost me $250 for a new armature and field coil and not long after that the regulator packed up so it was another $120 for an electronic reg. After that I had 60watts (I didnt cut the reg wire to go to 12v) With the last VH I built I needed a generator and when I priced the Alton it was only a few dollars more than what I had spent on the last set up and that included the regulator. Paul was great to deal with and I had the unit within a week. Since fitting the Alton I couldnt be happier. I am running a Xenon 60W headlight so that I can see at night and there is enough power left to run handle bar heaters. Worth thinking about rather than chasing your tail.
David

[john.nash]

Alton's are around £330
Compared to the £22 for a Field coil for this one ?