VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1940s' Starter Armature

I have no electrical background so please excuse my terminology, etc. I have three starters that I am rebuilding and have two with damaged armatures. The one on the left (top far left) has a half inch of exposed wire that goes across the armature. The one at the right has several exposed wires. The left armature seems to use some king of varnish material to keep the wires isolated, the right one seems to have a rubber encasing all the crossing wires. I checked all the exposed wires with a volt meter and non seem to be grounding onto the wide silver bands. I assumed I could epoxy over, or varnish over the exposed wires and that should fix the armatures?

I also have the cloth wrap on a field that is frayed and is unwrapping. I thought this could be easily fixed by also using some varnish to reseal the cloth to the field. Is this okay?

Lastly is their anything else that I should be looking carefully at? I have read through the manual and lacking the instruments to do tests will test the starters on an old engine I have mounted on the front of a sawed off car frame. Thanks, Mike

P.S. I did post this in the "Electrical- 6 Volt" Forum.

Mike, I'm no expert at this but my brother used to rewind electric motors all the time as part of his trade and he used varnish to insulate the wiring in them. I think you are on the right track if nothing is shorted. I think he actually dipped parts in varnish, ofcourse you wouldn't want to dip the commutators (sp).

Mike
Both armatures have a winding that appears to be very close to rubbing on the pole shoes which will cause problems. Apart from rewinding them I dont think there is a sure way of fixing that problem.
The right hand 1 may well only be that way from rubbing in the frayed pole winding cloth though.
Tony

When these armatures were wound originally,they were dipped in a liquid bakelite solution,then cured in an oven,hence the "flaking" of the the brown bakelite on both armature pictures,as it becomes brittle with age.
If from your tests you have no short circuits or earthed armature windings,the best thing to do would be to preheat the armatures in a small baking oven,then submerge them in a polyester type varnish.I use Isonel 30-98,and it needs to be baked at around 140 degrees centigrade for at least 3 hours.
If the cotton ape is fraying off the field coils,it would be best to get them stripped,washed,dried and retaped.Then fitted to the field frame.After all this time,they're probably full of oil and copper carbon dust from the brushes as they wear.
Check the shaft for bend in a pair of "V" blocks,the drive end plate bushing for wear(if worn excessively it could cause the armature to "pole" on the field pole pieces,and the clearance of the commutator end shaft in the brush gear end plate.If you find excessive clearance there,get the endplate bored & fitted with a porous bronze bush.I use "SINTALITE" brand here in Australia on my re-builds.

Mike,
Let me see if I can help you a little. First off, if I were rebuilding these starters I would not re-use these armatures. With that said, I'm not saying they will fail right away, but I would not be able to stand behind the rebuilt unit they are going in. Originally the wire itself had a varnish coating on them, the steel laminations had a fiber insulator on both ends to keep the turns from grounding, and they had a sleeving pressed in. I can see in yours, the varnish is missing, the sleeves are damaged and missing in spots. If I remember correctly the one on the right has started to rub, which indicates it is starting to lift out of its slot. Without banding it you will not be able to keep it put. Feel free to contact me with any questions. I also should have these armatures in stock. Go to my website for complete contact info.
Jason
Advanced Electrical Rebuilders
Grand Ledge, MI
www.aerrebuild.com

The original coils were formed from bare tinned copper section with no varnish on the conductor.The armatures were dry wound,using "fish paper"(just a form of paper)as slot insulation,
and had a piece of "fish paper" to separate the top & bottom leads.The lamination end insulators were usually made from grey fibre,much like red fibre washers are today.There were NEVER any binders on these armatures,as Delco-Remy relied on the armature being impregnated with liquid bakelite,then cured under heat.
The flaking you see in the photos is the original bakelite dipping insulation coming off,as it gets brittle with age.As long as the coil sides aren't loose in the slots,then a good polyester baking varnish will be more than satisfactory to hold the coils.

Thanks everyone for the help. The three starters I am cleaning up were from various engines/cars I have salvaged for parts. I enjoy trying to clean things up and salvage them! This weekend I used some varnish and a small brush to paint over the damaged areas. The one armature had only about a half inch of damage on it so I see it as being okay to rebuild and reuse. The one on the right I damaged the insulation by lightly sandblasting the armature to get a lot of rust off of it. So I do not see a problem with the copper wire raising up and the insulation being worn off causing an eventual failure of the armature. But taking everyones best advice I do think I should walk away from that armature.

In my unsupervised time I like to not only work on my 41/77 but locate inexpensive project cars/engines and salvage parts. I have a nice two story garage so store my cleaned up parts in the attic. My latest find was a 47 engine sitting on its sawed off front frame in a field. Hopefully, I can sell some of the parts back to Chevs of the 40's and end up with some nice parts. As some of you know I have sold parts on this site, and will continue to help others with parts as I can. I think there is a real need for sources of parts that are not available in our catalogs, and hope those with extra parts are not just throwing things out?

Really appreciate everyones help, especially the Australians. Glad you got to see Tiger.