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[General] Bosch alternator, fix/replace regulator brushes

Discussion in 'Holden Commodore How-To's' started by Jxfwsf, Mar 6, 2012.

  1. Jxfwsf

    Jxfwsf Well-Known Member

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    Don't you hate it when you're driving along and that damn red charge light comes on?
    Check all leads and connections on the alternator and battery are good and nothing has come off.
    When you're checking the signal/light plug on the reg you hear the alternator kick in and whine, push the plug another direction and it cuts out again..... well looks to be an issue with the reg and brush contact.

    A set of new brushes and spring will set you back about $10, if the rest of the alternator is still in serviceable condition, slip ring isn't worn to far and grooved to deeply, bearings are okay and not noisy etc.... it'll be a cheap fix.
    a new reg is about $40-60 and a new alternator is in the 100's.

    Images are of a buick 3.8 but once you have the alternator moved to a point and can access the screws to remove the regulator it'll be the same from there.
    Covers anything with a bosch alternator, from an old hq to anything new with this style regulator.

    Disconnect the battery, this is a must and you shouldn't skip this step failing to do so will result in shorts and sparks when you try to remove the reg and may blow the thin metal contacts to pieces inside the alternator.

    Remove the belt and start undoing the alternator, remove 1 bolt and you may need to loosen the swivel point.
    Remove the signal and light plug and rotate the alternator so you can access the screws holding the reg in

    [​IMG] [​IMG]
    [​IMG] [​IMG]
    [​IMG] [​IMG]

    Undo the regulator and check the contacts inside the alternator for excessive wear or corrosion, make sure there is no grease or oil on them as this will cause arcing and premature wearing of the copper and brushes (this is what kills alternators in chooktins, p/steering leaks over them and they burn out).
    Slightly worn in this pic but it's still got some life left in it, if they're black and dirty get a small piece of emery paper etc and push down lightly and rotate the pulley to clean them up.


    Get the soldering iron hot and start removing the old brushes. Lift/bend the tab up so you see the hole where the braid feeds thru.

    [​IMG] [​IMG]

    Remove the old brushes and as much solder as you can (desoldering braid or a solder sucker come in handy for this)

    [​IMG] [​IMG]

    Install the new brushes, measure the braid length on the old set and mark the new ones (a texta mark will be fine, the flux in the solder will remove it) so you solder them in at the correct length.
    Reinstall the reg back into the alternator and bolt it all back togther.
    Last edited: Mar 7, 2012
  2. RUN415

    RUN415 Member

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    Dec 6, 2011
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    = Oct 2016 - Update =

    New Alternator = $200+
    New Regulator = $60 ---> $100
    Brushes = Under $10

    Note 1 : Brushes were no longer available at Repco, Supercheap, Autobarn etc. (or the wreckers for that matter.)
    I did find an auto electrician who sold them and also sold Regulators at the cheapest price. ($60 or $72 depending on the type)
    So my advice would be to seek out an auto electrician when you're sourcing or pricing parts. [See note 2]

    Note 2 : I've been advised by two people (an auto electrician and the Repco parts guy)
    that when the brushes are worn, overheating and/or damage MAY occur in the Regulator unit
    which MAY result in damage.
    It is generally recommended therefore, to replace the entire Regulator...
    ...which is why, I guess, it's hard these days to just buy the brushes.
    So this is probably the best option if you have the cash and/or can't solder.


    PS> Thanks for this post 'Jxfwsf'...I know it's old but was very helpful.
  3. EYY

    EYY Well-Known Member

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    Repco and supercheap can get the regulators in for you (for a decent price iirc), and the local wreckers here has more regulators than you can count. Most of the ones I've had/seen fail haven't failed through worn brushes, they just stop regulating or stop working altogether. Always good to replace the unit

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