Dynamo Rebuild

Rikki White · Post by **Rikki White** » Tue Feb 20, 2007 5:41 pm

Can anyone recommend someone that could rebuild/refurb my dynamo.

Many thanks

Biscuit · Post by **Biscuit** » Tue Feb 20, 2007 7:40 pm

Rikki, unless you have very deep pockets, I would earnestly recommend that you consider doing this your self, it's not difficult and with care and attention is achievable.

Some of the prices members have paid, quoted on this site are astronomical

Don Madden · Post by **Don Madden** » Wed Feb 21, 2007 2:12 am

The archives hold copies of the original Lucas service sheets giving details of overhaul of these & other components.

Read the relavent ones & see if you can manage the repair, perhaps with help from the forum.

Cheers, Don.

lolski · Post by **lolski** » Wed Feb 21, 2007 6:53 pm

Hi Rikki i rebuilt my dynamo and as Biscuit and Don say its not to difficult with the help of the forum if you have use of a lathe or know some body you might have to skim commutator you could take some pictures as a reference as you take things apart good luck if you go down this route

regards lolski

lawrence · Post by **lawrence** » Wed Feb 21, 2007 8:04 pm

Hi Rikki
Welcome to the forum!

Just to give a different viewpoint I disagree with the others. Unless you have a large degree of engineering sensibility and can fabricate the pullers etc you will need I would send it to a specialist rebuilder.

They are very simple and properly assembled will run for years with little attention. I had mine rebuilt for about £125 and it ran for 4000 miles trouble free. Then I fitted electronic ignition . Unwittingly, by doing this I took the load way over the maximum 65W on 12V. About a thousand miles later the dynamo developed a massive through oil leak and stopped working. The armature had burnt out and taken the oil seal with it. Rebuild No.2 and a short while later the oil seal went again. Lawrence thinks “I’m not going to pay to have an oil seal replaced, it’s an easy job”. I replaced the oil seal and in doing so cracked the end bridge as I lightly tapped the gear home with a miniature hammer. This allowed the armature to ‘flap’ as it rotated so rubbing on the field coil which eventually failed under the heat generated. Back it goes to the rebuilder who says to me “What are you doing to this unit, besides the field coil the armature is also nearly melted again”.

He ran through the load with me, ‘55w headlight, 5w sidelight (Jap lighting switch so lights with headlight), 5w speedo light, the rear/brake light is LED and indicators don’t count’ so you are just in the limit’. You have a mag as well don’t you? Er, yes says I, it is sitting on the workbench as I have fitted EI. Right, says he, you know they take up to 20w or more do you? This caused all my troubles (I hope). I have downgraded my headlight to 35w halogen and off we go again. After our little chat I re-read the fact sheet he sent with the refurbished dynamo and it stated DO NOT EXCEED 65W LOAD.

With postage and multiple rebuilds I think my dynamo has cost me about £400, mainly due to my inexperience. I would definitely recommend a pro rebuild and DO NOT OVERLOAD IT! If you do rebuild it yourself, and they are indeed simple items, use pushers and pullers and not a hammer for anything.

Just to prove I haven’t learnt anything, next time mine goes outside guarantee I am rebuilding it myself!

Good luck

Blast and double blast! First decent run on the new dynamo and it is pyssink oil through it like the Torrey Canyon. So much for the blow-by caused by dynamo overload theory. back it goes to the professional for about the fifth time. There has to be a problem with the track that the oil seal runs on. Next time I will definitely rebuild it myself. At least then I am adding to my experience, not my debt.Edited by - lawrence on 23 Feb 2007 10:38:21 PM

Biscuit · Post by **Biscuit** » Wed Feb 21, 2007 8:11 pm

Knickers Lawrence. Don't you dare dent his confidence!!!!

56G80S · Post by **56G80S** » Wed Feb 21, 2007 9:00 pm

I expect to be doing this before very long myself, when I can find time away from work, three kids and my desperate urge to dismantle my body by continuing to train for and play squash competitively at an advanced age.

My advice is to listen to Alan and Don, when dismantling draw pictures or use digi camera, make notes and be gentle and slow if things appear not to want to release. When pulling or pressing allow time for things to act rather than winding things too fast amd dont use parts of the dynamo to lever against - particularly the armature itself.

Only hope I have the patience to heed my own advice; not famous for it.

Johnny B

Duncan · Post by **Duncan** » Wed Feb 21, 2007 9:07 pm

I had mine refurbished by Tony Cooper – T.C. Motorcycles 0121-559-2405, I have not tested it yet but do not anticipate any problems as he has refurbished a Magneto for me in the past. It cost in the region of £80, you can also get the service parts from him if you decide to go DIY.

Alternatively Paul Goff can supply parts see www.norbsa02.freeuk.com/goffyelectrex.htm, there is usually an advert in the OBM as well

Duncan · Post by **Duncan** » Wed Feb 21, 2007 9:18 pm

Should have said that if you go to Kempton Park you can normally see Sean Hawker, Tony Cooper and Paul Goff if you decide to use any of them and save on the cost of posting the dynamo or DIY service parts.

Biscuit · Post by **Biscuit** » Fri Feb 23, 2007 11:24 pm

Don't you just hate people who say 'I told you so' Lawrence?

Obviously your repairer knows more than I, but I can't grasp what the electrical load has to do with overloading the dynamo, direct lighting yes, but in our situation the load is on the battery, which the dynamo tops up. The regulator controls the dynamo potential and the internal resistance of the battery controls the current. If the battery cannot supply the load, then it gradually discharges, the dynamo tries to keep up but it can't. It may be working at full capacity which isn't the same as overload.

Someone will now point out the error in my reasoning

Edited by - Biscuit on 23 Feb 2007 11:35:19 PMEdited by - Biscuit on 23 Feb 2007 11:37:04 PM