Author Topic: Alternator Brushes  (Read 101 times)

Offline stokester

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Alternator Brushes
« on: April 07, 2018, 02:14:41 PM »
In today's world of installing rebuilt alternators I do like to go back where brushes were replaced and need to on my BMW Airhead motorcycles.  I recently had to replace the rotor, updated the diode board and voltage regulator with modern components and noticed the brushes were looking  a bit short.

On these motorcycles the rotor is driven off of the end of the crank with a tapered press fit so after removing the front chest cover I only needed to remove the outer case and stator to take it to the bench for dismantling and soldering.  As you can see, the brush is a bit shorter than the replacement but after about 75K miles I guess it was due new brushes and springs.


_Nick
vwradios.com

Offline goodfellow

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Re: Alternator Brushes
« Reply #1 on: April 07, 2018, 03:31:06 PM »
Pretty cool! -- looks like a lot of wear for 75K. A great DIY fix!!  thumbsup2 thumbsup2

Offline stokester

  • Sr. Member
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  • Join Date: Jan 2014
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  • Location: Yorktown, Virginia
  • Airhead Aficionado
    • Classic VW Radios
Re: Alternator Brushes
« Reply #2 on: April 07, 2018, 07:50:27 PM »
Pretty cool! -- looks like a lot of wear for 75K. A great DIY fix!!  thumbsup2 thumbsup2
Yes, brush wear on slip rings should be minimal but possibly in the environment of a motorcycle it is greater.  RPMs are generally higher (3500 - 4000 at cruise) and with an air-cooled, the operating temperatures vary significantly.  The temperature swings is what causes the rotors to fail as the wire insulation breaks down.
_Nick
vwradios.com

The Garage Gazette

Re: Alternator Brushes
« Reply #2 on: April 07, 2018, 07:50:27 PM »