Scary lower drop gear damage...where should I look for the missing teeth!? | FerrariChat
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Scary lower drop gear damage...where should I look for the missing teeth!?

Discussion in '308/328' started by jimmynail, Sep 2, 2009.

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  1. jimmynail

    jimmynail Rookie

    Aug 22, 2008
    17
    Playa Del Rey, CA
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    Jimmy N
    #1 jimmynail, Sep 2, 2009
    Last edited by a moderator: Sep 7, 2017
    For some time I've noticed a rattling sound coming from my transfer case when the car idles in neutral. The sound would go away when the clutch was depressed. It was unclear if the sound was present in other gears. So I decided to open up the transfer case and take a look...

    As the attached pics show, the bottom drop gear is missing a few teeth! Amazingly, the other two gears are flawless, even the middle gear that was meshing with the destroyed lower gear has no damage that I can see.

    The oil plugs have been pretty clean for the last few changes- I've only done two since I purchased the car a year ago.

    Another clue that might be unrelated- the transfer cover shows scaring from the lower drop gear and ring nut. From the looks of it, this may have occurred at a different time, it is really hard to tell. Also, the ring nut and shaft are pretty chewed up, large chunks missing as seen in the picture.

    At this point, I plan to replace all three gears with a matched set. Some lingering questions...

    -What is the flow of oil...where should I look for the missing teeth fragments?
    -Any idea what might have caused the scaring? Loose ring nut or incorrect gear?

    Thanks in advance!
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  2. FF8929

    FF8929 Formula Junior

    Apr 12, 2008
    799
    Livonia, Michigan
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    Fred Flynn
    #2 FF8929, Sep 2, 2009
    The "mechanic" (ax murderer) who worked on that lower ring nut should be "gut-shot"! It just disgusts me to see machinery treated that way.
     
  3. mustardfj40

    mustardfj40 Formula 3

    Jun 17, 2004
    1,142
    Northen California
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    Ken
    #3 mustardfj40, Sep 2, 2009
    Yep, looked like whoever worked on it previously used a chisel/hammer to turn the nuts, can't believe that was done to a Ferrari. Ouch!
     
  4. theunissenguido

    theunissenguido F1 Rookie
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    Guido
    #4 theunissenguido, Sep 3, 2009
    Those missing teeth are not there anymore. This happend before and the upper gears are already changed I suppose. Otherwise they are damaged also and the cover would have been scrached alot. If I where you, I just change the lower gear and gearnut. Flush the oil from the transfercase and look if there are some metalparts on the oilchange nut. Normaly it has a magnetic top.
    Take of the middel gear and see if the bearings are clean. Also see if that little oil hole on the left side of this gear is open.

    Guido
     
  5. fastradio

    fastradio F1 Rookie
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    Apr 26, 2006
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    David Feinberg
    #5 fastradio, Sep 3, 2009
    Sadly, a semi-familiar sight....as someone though those nuts could:

    -Be removed without the correct tool
    -Be re-used, versus installing a new nut and peening it "in place"
    -Be reinstalled; i.e. torqued correctly without said tool

    With a new lower gear from Ferrari now approching $2,900, this will be a costly repair, even using used parts. One can help but wonder if those broken gear teeth weren't "wangered" when the "pro" used their air hammer to remove that lower nut. I sure hope the shaft coming out of the tranaxle wasn't damaged, as well.

    Best,
    David
     
  6. rizzo308

    rizzo308 F1 Rookie
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    riggio
    #6 rizzo308, Sep 3, 2009
    who ever did that needs to be hunted down and face the Fchat jury or better still we can all have a go at knocking his teeth out with a cold chisel..... i'll have nightmares tonite
     
  7. Ricambi America

    Ricambi America F1 World Champ
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    Dec 7, 2003
    16,451
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    #7 Ricambi America, Sep 3, 2009
    Last edited: Sep 3, 2009
  8. Doug

    Doug Formula 3

    Nov 13, 2003
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    #8 Doug, Sep 3, 2009
  9. jimmynail

    jimmynail Rookie

    Aug 22, 2008
    17
    Playa Del Rey, CA
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    Jimmy N
    #9 jimmynail, Sep 3, 2009
    Yeah, I'm beginning to believe that the previous owner assembled it this way, teeth missing and all.

    New Hill Eng nut + tool ordered from Ricambi. Might have found a decent deal on a gear from Bill @ GT Auto Parts.

    What's the consensus on replacing a single gear vs. going for a set?
     
  10. robbie

    robbie F1 Rookie

    Aug 26, 2005
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    Robert
    #10 robbie, Sep 3, 2009
    What is your peace-of-mind worth? I'd spend the Benjamins and get the set.
     
  11. swift53

    swift53 F1 Veteran
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    Alberto
    #11 swift53, Sep 3, 2009
    Jimmy,
    I got three used gears from Peter at Forza Motor - [email protected] - at a very reasonable price. Gears are gears, they are not a matched set. We have been mix and matching gears in other European makes for a long time and never had a problem,unless a gear failed due to bad metallurgy.
    When you replace a gear inside a transmission you do not buy all the other ones, right?
    Regards,
    Alberto
     
  12. mustardfj40

    mustardfj40 Formula 3

    Jun 17, 2004
    1,142
    Northen California
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    Ken
    #12 mustardfj40, Sep 3, 2009
    I don't know about Ferrari specifically but on my other project, I replaced my transfer case gear as a set, they are like differential ring and pinion on which is sold as a set and with time and mileage they wear out together. I think you can replace one in a bind but usually they make more noise and wear out each other faster.
     

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