Alternator Overhaul

Starting to drive the Datsun Roadster again, on the off halfway clear days here. Did the 5spd trans swap with new clutch. Much better.
I noticed the battery was suddenly low, when the tunes cut out and the electronic ignition shut down..... Pulled and tore done the alt. I had modified and installed an Nippondenso alternator; a small 65A unit common on 80's Toyota P/Us. The rotor was fried, and the brushes burned out. Shit. Picked up a used replacement for $40 and stripped it down. EOL...the brushes were very short and the slip rings deeply grooved almost to the min diameter. I turned the slip rings to .510, .006 above the min. Turned a copper slug to .750 dia and .835 length, the length of both slip rings. Bored for a .002 interference fit, heated it and shrunk it on to the slip ring set on the rotor. Turned it to .635, the max slip ring dia, and used a parting tool to cut to the insulation between the rings, forming two new slip rings. A little emery....perfect. Swapped parts as req between the 2 alts to make a good unit. Picked up a new brush set at O'Reilly ($4.00) and soldered them into the brush holder. Works perfect. JR
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JR North wrote:

It's nice when things work out the way you planned, isn't it?
You prolly saved a few hundred bucks over taking it to a dealer for an alternator replacement.
Jeff (Who wishes he didn't remember how little auto parts cost in the '50s.)
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Jeffry Wisnia
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On Fri, 22 Apr 2011 11:18:25 -0400, jeff_wisnia

--snip--
You bet. The Parts Departments of Honda and Toyota both seem to think that the minimum price on any one item should never be less than $400.00. Go figure.
-- Accept the pain, cherish the joys, resolve the regrets; then can come the best of benedictions - 'If I had my life to live over, I'd do it all the same.' -- Joan McIntosh
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Larry Jaques wrote:

Sheesh! Back only a decade or so, I could get a rebuilt Chrysler alternator for about fifteen bucks! Of course, that counts the core allowance for the old one I traded in.
Thanks, Rich
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JR North wrote:
(...)

You left out the part where you smelted the copper from ore. :)
But seriously though. Good Man, Jason!
--Winston
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It's now probably better than new.
One caution... emery cloth/paper is conductive, and really shouldn't be used on slip rings, commutators, contacts or around electrical equipment in general.
Erik
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I doubt you'll get a reading right off the cloth/paper, it's the grit left behind thats conductive.
As I recall from A&P school, microscopic emery 'inclusions' also end up embedded in soft materials like copper that can raise hell with brushes, and promote arcing.
They said sand paper only... and if you were using it to seat generator/starter/motor brushes, to be absolutely sure no sand particles were left under a brush, stuck between commutator segments or generally loose where they could blow into wherever.
Erik

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Erik wrote:

Some years ago I had a couple of "brush seating sticks" to be used after installing new brushes.
They were white, a few inches long, and about 1/4" x3/8" cross section.
You'd press them against the commutator next to a brush while it was spinning and the white stuff ground the contacting surface of the brushe to become a good mate with the commutator.
Guess they're still around:
http://www.goodvac.com/Rainbow_brush_seating_stick_p/r-prt-seatingstone.htm
Jeff
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Hmmm, first I've ever heard of this!
Looks like it's mostly silica sand:
<http://www.msdsxchange.com/english/show_msds.cfm?paramid1 $05943>
Erik
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jeff_wisnia wrote:

I used to use those large gray ink erasers to polish the armature. I was rebuilding vacuum cleaner motors as a side business. A lot only needed new brushes and to clean the armature. They ran fine on a variable DC power supply, which made it easy & safe to polish them while running.
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jeff_wisnia wrote:

I use them quite often. They come in different sizes and grits. On the little tach generators I just use an eraser on the back of a pencil since they usually just get a coating on them.
John
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On Sun, 24 Apr 2011 13:51:03 -0400, jeff_wisnia

I use these at work on large dc motors to clean up a worn commutator. A bit pricier, with fine mediun and course grades depending on the wear on the commutator. If its really bad then turning on a lathe is required. The white sticks are used to seat the new brushs to the commutator. http://www.drillspot.com/products/45229/ideal_industries_inc_80-075f_commutator_resurfacer
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On Sat, 23 Apr 2011 10:35:37 -0400, "Stormin Mormon"
Use aluminum oxide, (sold as commutator paper in rolls) or for fine polishing, crucus cloth. NEVER Emery.
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On Sat, 23 Apr 2011 10:35:37 -0400, "Stormin Mormon"
Emery is a mix of magnetite and corundum, if I remember correctly. Magnetite is an iron oxide (Fe3O4) and IS conductive.
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On Fri, 22 Apr 2011 08:12:37 -0700, JR North

Most excellent, sir. Kudos.
-- Accept the pain, cherish the joys, resolve the regrets; then can come the best of benedictions - 'If I had my life to live over, I'd do it all the same.' -- Joan McIntosh
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