24V 84 bj42 alternator charging trouble and voltage regulator confusion (1 Viewer)

jim land

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new trouble with my charging system , filter and brake light stay on all the time for a week now , voltage on the battery is 24.4 with the throttle slightly pull , with the headlights on it drop to 23.8 , same voltage numbers on the b+ post on top of alternator , i've done a lots of reading and hope its the brushes .

im confuse about the VR , it is mounted to the cowl , so its an external regulator , right ?
i saw pics of internal VR alternator that look just like mine
i will post pics for expert advices like @bj40green 🙂
 
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jim land

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jim land

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I think this could be the problem 🧐 less than 3mm , minimum is 5.5 .

Questions

1- New set should be at 20mm ?
2- Do i need specific brushes or is generic ok ?
3- should i clean inside the alternator where the brushes tips contact ?

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Slip ring on OEM are in stainless, not much to clean. I would start by changing brush.
Just had a close look at your pic and seem to have lots of dust from brush?
Would be good to take appart the unit and give a good clean, inspect slip ring surface.

Edit: if you take appart the alt, change the bearing in the front, not expensive. Jammed on mine and at the end damaged my rotor.... they are difficult ro source.
 
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jim land

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It work 😁 new brushes and a little cleaning , the bearing is good .
Brake and filter light are no longer lit and normal voltage is back

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Had a very similar issue occur. Took the alternator to a small town alternator shop. Got the call a week later to come pick it up and when I did, the guy told me it looked good, but he couldn't test it... Didn't have a cradle for it, or something. Put it in, still throwing low voltage. I finally took it to a shop, since I was going to be gone on business for a few months... When they finally took a look at it, they said it was the alternator. Now, I'm waiting for them to find the time in their busy schedule to remove it so I can get it rebuilt.
 

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