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C39 Lucas Dynamo rebuild - Moss armature does not fit

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angelfj1

angelfj1

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You know, I really get ****** off when suppliers do this.

We recently bought a replacement armature from Moss USA, part number 162-900, for $42.95. I was very impressed with the quality of this piece and the price seemed fair.

BUT, here we are in the 11th hour trying to fit the new dynamo and discovered, to our astonishment that the keyway/key in the new armature shaft is smaller than that in the original fan/pulley!

AND

The original nut does not fit the new armature shaft. I bet its metric.

This is going to be a very difficult fix.

OK - what really frosts me to no end is that there is/was no indication in the parts list or in the box that this part was in any way different from the original.

So, if you plan an armature replacement, a word to the wise!!!

Gee I'm ******!!!:madder:
 
If the keyway is too small, you can re-cut it to the appropriate size without the need to re-cut the pulley. I have noted your electrical problems and can relate. I have a 1969 GTO that I restored and rewired. The alternator fried itself every 200 miles. Replaced armature several times, stator several times, and diodes several times. After the sixth time failing they finally replaced the internal voltage regulator and have not had a problem in the last 4000 miles. If your generator fails again consider replacing your solid state voltage regulator with another one. You may have a component in the regulator with a transient fault that allows the voltage or current to spike and burn up the generator, all the while testing OK on the bench.
Robert
 
In looking at the Moss web site, it appears that they sell only parts for the later C40 generator, and that might well be the armature they sent you? According to Lucas, the C39 and C40 armatures are different and have different nuts as well. They do fit the same end bearing and bushing, but that's about it; most other parts are different.

Oh, and the Lucas p/n for the C39 armature is 227693; p/n for the nut is 180740. (This is assuming an original 22258 generator.)

I also found an online source that implies that the armatures are somewhat interchangeable. (Presumably you would have to source the correct nut, key and maybe even pulley from a C40?)

https://www.aspwholesale.com/index.php?act=viewProd&productId=8055
 
Last edited:
The dynamo has been completely rebuilt.

We replaced the armature, field coils, front and rear bearings, basically a new dynamo. We did all of this work to retain the correct and original case with proper date code.

some notes:

The armature available from Moss USA is metric. It has a key way narrower than the pulley and fan. This required a special key which had to be milled. In addition, the nut which secures the fan and pulley is metric, so the original nut will not fit. It would have been helpful for Moss to indicate the differences between this replacement armature and the original Lucas unit.

The front open cage ball bearing was replaced with a sealed, lifetime lubricated unit, model 6201, German made (INA). https://www.mcmaster....earings/=n4pzny

The rear oilite bronze bushing was replaced with a needle bearing. (model number later). The needle bearing has a lubrication grove. We were careful to retain the original felt which we will keep oiled and it should feed lubrication to the new bearing.

The new dynamo spins very freely with no noticeable radial or lateral deviation.

I am currently using an original Lucas, electromechanical control box. I believe there is an intermittent fault in the solid state unit I had been using, perhaps one of the electronic components is breaking down. I have returned this for evaluation.

For long trips I intend to travel with a spare dynamo and control box.

Additional detail later as I gain experience.

Cheers,

Frank
biggrin.png
 
angelfj said:
... For long trips I intend to travel with a spare dynamo and control box.
Click to expand...

I always do. Yeah, you can drive hundreds of miles w/o a generator and forever with a friend who will swap batteries with you from time to time but a spare is handy. Had to use it once to save a Mini on our tour when his dynamo died on the Navajo Reservation.
 
Frank I think I heard you were planning on going the TRA, I hope this does not interfere with your plans. I sure would love to drive down the tree lined back roads of Kentucky.
 
Hi, Since you're taking a spare, your trip will be a perfect road test. I'm curious about the needle bearing. Do the needles ride on the armature shaft surface? I think I would use a slightly heavier oil than with the bushing, especially with the likely unknown of the shaft's hardness. As mentioned above the armatures are somewhat interchangeable, if you use a 40 armature with 39 field coils you gain about an amp over a stock 39/39 set up. With the reverse 39 arm and 40 fields, you wind up with about an amp less than a 40/40, having tested both set ups. Have a great trip.
 
I still wondering about the needle bearings from the lubrication standpoint. After I started rebuilding my own generators and insuring that the oilite bushing was soaked in oil for 24 hours (heated initially), I had very good luck with generators lasting.

Scott
 
angelfj said:
I am currently using an original Lucas, electromechanical control box. I believe there is an intermittent fault in the solid state unit I had been using, perhaps one of the electronic components is breaking down. I have returned this for evaluation.
biggrin.png
Click to expand...

Frank...

In this thread and earlier ones you mentioned the upgrade of your generator to the electronic version that was done by Bob Jeffers at Wilton. I had planned to have the same upgrade completed on mine and had exchanged e-mail with Bob earlier this year. I was getting ready to send mine off to him recently when I heard the sad news that he had passed away.

A club member told me that I should check out a company in the UK called "Classic Dynamo & Regulator Conversions". That company can be found here: https://www.dynamoregulatorconversions.com. After sifting through the information on their site it appears that they provide a similar service. Have you (or anyone else on the forum) had any experience with this company? Were you ever able to find any other local company in the US to help resolve the problem with your electronic version?

Rick...
 
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