Are this surfaces OK for to put new synchros? | FerrariChat
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Are this surfaces OK for to put new synchros?

Discussion in 'Technical Q&A' started by fishing, Mar 1, 2008.

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  1. fishing

    fishing Karting

    Sep 3, 2006
    137
    Norway
    Full Name:
    Harald
    #1 fishing, Mar 1, 2008
    Last edited by a moderator: Sep 7, 2017
  2. RMDC

    RMDC Formula 3

    May 15, 2005
    1,005
    Boston, North Shore
    #2 RMDC, Mar 1, 2008
    Verell?
     
  3. fastradio

    fastradio F1 Rookie
    BANNED Professional Ferrari Technician

    Apr 26, 2006
    3,664
    New England
    Full Name:
    David Feinberg
    #3 fastradio, Mar 1, 2008
    Harald,

    I've rebuild more than my fair share of these gearboxes and can't recall ever seeing those groves. This is not necessarily a bad thing, as it would appear from you photos that these "rings" are machined-in grooves, rather than wear. Presuming that I am correct, we're concerned about two other items.

    (If I'm incorrect...and those grooves are indeed from wear, or lack of lubrication....a gear set is in order. You'll need to inspect this area and the old synchros very carefully for a determination.)

    -1) The teeth on the gears (4th gear looks very serviceable, 5th gear looks fine!
    -2) Here's the big decision maker...If you have the new snychro rings, push them down over the cone and measure the clearance (gap) between the two synchro ring/slder surfaces. The factory WSM gives this spec. If you have less than the spec, with a new syncro ring, the gear assembly is no longer useable, as the cone is worn "too steep"...hence, you don't have enough "material" remaining to match the speed of the shaft to the next gear your trying to engage.

    Although the cone and corresponding teeth appear to be a replaceable item, and similar to an old Volvo truck, sourcing these parts typically is futile...despite the undertones that they are/might be avaialble.

    Regards,
    David
     
  4. fishing

    fishing Karting

    Sep 3, 2006
    137
    Norway
    Full Name:
    Harald
    #4 fishing, Mar 2, 2008

    This grooves are machined. And those grooves are showing some wear. The synchro in 4th gear did not have any clearance. 5th gear is also under the clearance limit.
    I did not buy the synchros yet so I can not check them together with new synchros.

    The 1st gear did not have this grooves, but they also have different synchros.
     
  5. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
    5,379
    NWA
    Full Name:
    Paul
    #5 Artvonne, Mar 2, 2008
    How are you considering the wear on the grooves? Those are not supposed to be like screw threads with sharp edges, they are simply grooves machined into the smooth cone shaped surface and appear to look fine. As long as the rest of the gear looks serviceable, try a new syncro ring (clutch) on the gear and check clearance before condemning the gear.
     
  6. fishing

    fishing Karting

    Sep 3, 2006
    137
    Norway
    Full Name:
    Harald
    #6 fishing, Mar 2, 2008
    I going to order new synchros tomorrow and then I see. Thanks
     
  7. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    7,022
    Groton, MA
    Full Name:
    Verell Boaen
    #7 Verell, Mar 2, 2008
    Ferrari used 2 types of gear/synchro combinations:
    One set type the synchro inner conical surface is smooth, & the mating gear's outer conical surface was grooved. That's what you appear to have.

    In the other set type the synchro inner conical surface in the synchros was grooved & the gear's conical surface was smooth.

    In either case, the way that the gear's conical surface wear is checked is to place a new synchro on it & verify that the gap meets or exceeds the WSM Spec. There are drawings & descriptions of this test in almost all the WSMs from the GT4 WSM to the 308QV/328 WSM.
     

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