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348 alternator removal & rebuild

Discussion in 'Technical Q&A' started by ernie, Mar 12, 2007.

  1. ///Mike

    ///Mike F1 Veteran

    Dec 11, 2003
    5,990
    Bugtussle
    Glad it’s working again.

    Got the regulator from finditpart$$ and it at least seems to be a real Denso part (although counterfeiters have gotten pretty good these days).
     
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  3. Ga68_

    Ga68_ Karting

    Jul 16, 2017
    71
    France
    Full Name:
    Gaetan
  4. dahveedem

    dahveedem Formula 3

    Mar 12, 2012
    1,550
    Maryland
    Full Name:
    David
    I'll post this on the various Alternator posts so it's everywhere.

    For those of us who need the 103mm rectifier, I did confirm with Regitar earlier this week the only difference between the RN-02 and the RN-04 is the size of the stud.

    RN-02 -- 6mm stud
    RN-04 -- 8mm stud

    Both are 103mm and have the 8-50Amp diodes

    so they are both interchangeble by tapping out the stud and putting in the one from your old rectifier.
     
  5. dahveedem

    dahveedem Formula 3

    Mar 12, 2012
    1,550
    Maryland
    Full Name:
    David
    Interesting convo with an alternator rebuilder today. The 105amp version in my car was superseded to a 5071 for the last 4 digits of the part number Mike provided.

    When looked at the BOM for parts...it did list the RN-04 as the rectifier but he found a different voltage regulator... 126000-1500.

    I just put new brushes in, new rectifier new VR. It put out plenty of volts but only about 25 amps on his test bench.

    Maybe his RPM werent high enough?

    Stator looked good.

    Thoughts?



    Sent from my SM-G965U using Tapatalk
     
  6. dahveedem

    dahveedem Formula 3

    Mar 12, 2012
    1,550
    Maryland
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    David
    Anyone put their rebuilt alt on a test bench and see how many amps it was putting out?
    mine with new Denso Reg, new Regitar rectifier and new brushes is only putting out about 20amps.

    maybe a stator issue? anyone have that part number?
    Also some mention in a thread about the windings.. but everything looks good with them at this time.
    I'm half afraid to take her any distance as she'll leave me sitting.

    I've checked all the grounds, even made a new ground wire from Alt to chassis as the other one had some corrosion. No parasitic draw either.

    Help?
     
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  8. Mike Wroe

    Mike Wroe Rookie

    Jul 12, 2018
    1
    Full Name:
    David Michael Wroe
    Having had long time problems with the alternator on my 355 spider including multiple recoveries when it left me on the side of the road I took the plunge and rebuilt my alternator insitu using the parts recommended by Ernie only to find that it was still only putting out just over 13 volts as previously so I then trawled through the site and found the thread on 355 alternators and earth straps, back under the car and lo and behold there is no earth strap fitted to my alternator so I made one up out of heavy duty cable and fitted it and bingo 14+ volts so maybe I didn't need to rebuild the alternator after all. Just a warning to other 355 owners to check the alternator earth straps before getting into alternator rebuilds.
     
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  9. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,023
    The Brickyard
    Full Name:
    The Bad Guy
    Nice job, and good heads up.
     
  10. dahveedem

    dahveedem Formula 3

    Mar 12, 2012
    1,550
    Maryland
    Full Name:
    David
    So i never upated my thread on this?

    Whoops. Will post deets soon but a new stator and rotor fixed me right up.

    Sent from my SM-G965U using Tapatalk
     
  11. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,023
    The Brickyard
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    The Bad Guy
    Well get on it son!
     
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  13. dahveedem

    dahveedem Formula 3

    Mar 12, 2012
    1,550
    Maryland
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    David
    wow... I'm a bit late.

    303-52003 Rotor 80A-100A --- paid $49.87
    340-52002 Stator 4 Lead -- paid 30.91
     
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  14. AceMaster

    AceMaster Three Time F1 World Champ

    Feb 6, 2009
    30,675
    Calling a penalty
    Full Name:
    Mike
    Better late than never
     
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  15. Lolwut

    Lolwut Rookie

    Aug 21, 2019
    9
    Full Name:
    Sundeep
    Thanks for the thread. It was very helpful.

    That said, are there any special tricks for refitting the belt? I have the alternator back in but cannot get the belt back on for the life of me. I have the tensioner all the way loose and have tried to run the belt beside the tensioner for some extra slack without any luck. It is the correct belt (Dayco 199826).

    First time I have been defeated by a belt
    Help please!!
     
  16. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,023
    The Brickyard
    Full Name:
    The Bad Guy
    There where 2 different size belts. Take your old original belt with you to the parts store and just have them match it up. One belt is 774mm long while the other is 776mm long. Chances are you need the 776mm long belt.
     
  17. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
    3,885
    Sydney
    Full Name:
    Ian Riddell
    Are you sure you're screwing the tensioner in the right direction? I've been told the adjustment is counter-intuitive.
     

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