Not for sale, but need an opinion on a NOS part !

Over the last 20 years, despite doing less than 7,000 miles over that period, my W/NG has suffered from two failed modern rewound magneto armatures which I suspect were due to the condensors failing........

Instead of getting yet another armature reconditioned, I had a boxed NOS WD armature in deep storage.......I've had this for at least 12 years and since being in my ownership it's been kept boxed, sealed and warm within the house.............I recently opened it, and beneath all the wrappings the shellac insulation felt hard and with no deterioration visible at all...............I even took it to a magneto specialist who put it on a test rig for over an hour and the opinion was "a cracking blue spark - no issues at all"...................

I've read that most armature failures are due to condensors failing (modern rewinds) or the windings becoming corroded (NOS)..........added to that the shellac insulation softening and breaking down (NOS), in the main due to poor or damp storage............

But this one looks fine and has been tested..................do I use or fork-out (again) on yet another potentially risky re-wind ? There may be long-term risks both ways................

I'm certain we will have "two camps" here......!

If it has tested OK under load I would use it...The worst case scenario is that you may have to look at it again....

The alternatives are to scrap it or knowingly sell something on that you doubt is fit for service...

The first course would never prove whether the component is still sound, which testing indicates it may well be...

The second course could be regarded as unethical I would say...

I fitted a complete NOS madynamo to my B33 in 1978 and that one completed 52,000 miles before I had to replace a points end bearing..It then went on to do another 26,000 miles before overhaul...so you never know...

I have been offering a reconditioning service for magnetos and dynamos for 17 years...During that time I have averaged about 14 magnetos a year..So a total of around 240 units...There have been failures from all causes of approx. 4%...
That works out to 10 magnetos and is a failure rate I can work with...

The problem with any reconditioned piece of equipment is sorting out the wheat 'from the chaff'...They are all only as good as the components used and the skills of the person carrying out the work...

I have around 30-35,000 miles on the 'new' rewind currently fitted to my M20 and around 10,000 miles on my B33 with the same thing fitted...No problems with either machine....

From my experience I would say your record of failures in rewound armatures is not typical....Ian

email (option): ian@wright52.plus.com

Ian, as always, your reply is informative and appreciated ! Can't really get any better than this.........thanks mate !

May I ask, in your personal experience have the (few) failures been down to condensors ? I heard of some of the well-known reconditioners having been affected, on occasions, by "rogue" components............

Failures have not exclusively been down to condensors..I had a couple that had bearings coming loose in the housings...This was cured by a combination of thicker insulating washers and Loctite...

I've had one (magdyno unit)that had a problem with the dynamo clutch slipping...

And finally I've had a few with condenser failures after a short time....

There was a spell when there were some substandard components and the problem was that many people who recondition mags and dynamos use the same supplier for components and (mainly) two companies that do rewinds for 'ready to fit armatures'...

Thus the problem had the potential to affect many 'in the trade' which at that time it did...I haven't had any repetition of those problems for some time though...

Rob Miller was unlucky enough to have two mags done at that time which both failed and that also shook his confidence...

However, he is currently running a replacement unit and it's been OK this time...Ian

email (option): ian@wright52.plus.com