Suitable Dynamo for 1951 NH 350

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James Hickman
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Suitable Dynamo for 1951 NH 350

Postby James Hickman » Tue Dec 12, 2017 1:05 pm

Draganfly say Lucas E3LM

My contemporary parts list says E3LM L1-0

Have seen an E3LM-LO advertised

Mine has come with a non-functioning, tatty E3HM-LO (Which I'm sure isn't original)

Are they interchangeable? Do the different E3LMs (LO and L1-0) actually have significant differences?

Anyone know?

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Re: Suitable Dynamo for 1951 NH 350

Postby pete.collings » Tue Dec 12, 2017 5:47 pm

Looking at my Lucas catalogue covering the period 1936-57, E is eccentric mounted armature, 3 is 3" diameter, L is long type yoke and M is magneto mounted. It also lists a E3L for the NH range across those timespans, presumably as an upgrade to 60Watt output from the earlier E3H 48 watt output. It doesn't give any obvious explanation for your L0 or L1-0 suffix.
My experience is so long as the dynamo is compatable with mounting on a magdyno magneto, and has the correct 22t drive gear, it doesn't matter too much. Output/rotation can be altered by swopping the position of the brushes. I have rebuilt a number of dynamos on this basis.
The earlier drive gear was widened to suit the 60w dynamo and wider fibre drive gear on the magneto, Ebay offerings are usually the narrower type, although they can be used with the wider fibre wheel, it just loads a smaller area of the gear.

No doubt an expert on Lucas electrics may be able to improve on my observations above, but as a rule of thumb they should be helpful.

I have upgraded dynamos on previously owned Ariels to 12v by just purchasing an electronic regulator, and although this did not give me any particular problems, I think there is a risk if you use the outfut to the maximum frequently. There are 12v armature/field coil conversions available, I think these give greater output at lower rotation speeds. My magdyno single was fine, but my Huntmaster would not balance the QI headlight until 40mph.

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Re: Suitable Dynamo for 1951 NH 350

Postby admin » Tue Dec 12, 2017 5:56 pm

Image

i think the LO/LI codes are to do with rotation which you can change really easily anyway.

Long/short are interchangeable but ideally you need a long one - so one with an "L" in it - mainly because it's got more output
You can physically tell because the long ones have two screws, holding the field coil in the body and the short ones have one. The only other difference between a long/short one is obviously the armature length too. All the other bits, like end caps and bearings etc are common.
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Re: Suitable Dynamo for 1951 NH 350

Postby James Hickman » Wed Dec 13, 2017 6:25 pm

i think the LO/LI codes are to do with rotation which you can change really easily anyway.


Sorry - but I'm still learning lots... How do you change and how do you know if you need to change (is it just a matter of connecting the brushes the other way round...?

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Re: Suitable Dynamo for 1951 NH 350

Postby nevhunter » Wed Dec 13, 2017 9:46 pm

Running a higher voltage will require more field current. Probably not that much but these generators aren't internally cooled. No air goes through them like most car ones do. I have had the solder fling out where the wires are soldered into the commutator. When that happens all the wires centrifuge out and the armature needs rewinding. One place I know does this by welding the copper wire to the end of each commutator segment rather than soldering it. That should fix the problem which could happen any time you are "working it hard".. Nev

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Re: Suitable Dynamo for 1951 NH 350

Postby admin » Fri Dec 15, 2017 10:28 am

James Hickman wrote:
i think the LO/LI codes are to do with rotation which you can change really easily anyway.


Sorry - but I'm still learning lots... How do you change and how do you know if you need to change (is it just a matter of connecting the brushes the other way round...?


Yup. You can just swap the field leads over.

if you motor the dynamo then it will tell you which way it's going and you just check the rotation that the magneto is driving it and swap accordingly.

You can motor the dynamo by joining the F&D outputs together and touching then to the positive side of a battery. You need to attach the negative side of the battery to the dynamo body ( I clamp the dynamo in a vice and use a jump lead to the vice). That will spin the dynamo and show you it's rotation.
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Re: Suitable Dynamo for 1951 NH 350

Postby nevhunter » Sat Dec 16, 2017 1:43 am

The later bikes would have had the longer dynamo. It has a ball bearing both ends, bigger brushes and matches a bigger regulator which has a resistor in it the earlier one doesn't, which helps the regulator points to not arc as much. More regular action. The ammeter doesn't dance around as much. Easy to pick as it has (as John Says ) TWO screws on the top holding the field coil in place. You can't see one of them IF the strap is on holding it on the magneto. Nev

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Re: Suitable Dynamo for 1951 NH 350

Postby James Hickman » Mon Jan 22, 2018 6:43 pm

OK - I'm making progress and have learnt lots about Lucas dynamos! (As an aside James Smith's "Classic Motorcycle Electrics Manual" is excellent)

Some Lucas E3Ls I have seen advertised are fitted with a metal gear - presumably for direct drive rather than for maydyno mounting.

Anyone know if these could reasonably easily be converted by changing the drive end bearing plate to the more "triangular" one and fitting a fibre gear? If the armature is the same it looks like it should be relatively easy...

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Re: Suitable Dynamo for 1951 NH 350

Postby admin » Tue Jan 23, 2018 5:47 pm

The dynamo will have a metal gear.
The magdyno has the fibre driving gear.

the body and brush end of the dynamo is the same (the later ones have a different cover). However, the gear end cap will vary (by fitment) and so will the armature.
You should be able to get most of the bits second-hand - there are boxes of these bits at most autojumbles.
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