ZF S5 17 Synchro Ring Question | FerrariChat
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ZF S5 17 Synchro Ring Question

Discussion in 'Maserati' started by Jcgrimes, Oct 4, 2025 at 9:50 AM.

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  1. Jcgrimes

    Jcgrimes Rookie

    Dec 20, 2024
    20
    Full Name:
    John Grimes
    #1 Jcgrimes, Oct 4, 2025 at 9:50 AM
  2. redfred84

    redfred84 Formula Junior

    Dec 24, 2010
    756
    SF Bay Area, USA
    #2 redfred84, Oct 6, 2025 at 11:21 AM
    Actually it's the inner diameter of the brass syncro ring that does the work. It acts like a brake on the gear surface that it mates with. This is why it's important to use the proper, old fashioned gear oil for this application; NOT the modern synthetics.
     
  3. Jcgrimes

    Jcgrimes Rookie

    Dec 20, 2024
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    John Grimes
    #3 Jcgrimes, Oct 6, 2025 at 12:39 PM
    Thank you, Do you know what the tolerances are for this part?
     
  4. redfred84

    redfred84 Formula Junior

    Dec 24, 2010
    756
    SF Bay Area, USA
    #4 redfred84, Oct 7, 2025 at 10:54 AM
    No idea on tolerance. The ID of the brass ring actually "grabs" the mating surface of the steel gear, and acts as a brake. Any wear, or microscopic polishing can foul this up. It's probably not perceptable to the naked eye? This is why the gear lube is essential; it has to be the old fashioned oil. Sorry I don't have a good answer for you.
     
  5. Jcgrimes

    Jcgrimes Rookie

    Dec 20, 2024
    20
    Full Name:
    John Grimes
    #5 Jcgrimes, Oct 7, 2025 at 5:11 PM
    A little online research helps…the inside of the synchro ring has a slight taper which mates to a similar taper on the shaft, As the shifting fork pushes the synchro ring, the friction on this taper brings the ring and shaft to the same speed. As the inside of the synchro wears, the ring can move farther up the taper, until the synchro ring touches the gear on the shaft. At this point, the synchro ring can’t create friction ant the taper and needs replacement. On my transmission, this gap is pretty even for the rings at about .97mm. This appears to be about the standard clearance for synchro rings, so they look very good!
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