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308 clutch thickness

Discussion in '308/328' started by flyngti, Mar 9, 2010.

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  1. flyngti

    flyngti Formula 3

    Jul 16, 2009
    1,246
    Snohomish, WA
    Full Name:
    Eric L
    #1 flyngti, Mar 9, 2010
    Last edited by a moderator: Sep 7, 2017
    A recent post about 328 clutch thickness brought me to post something interesting (at least to me) about the clutch I just pulled out of my 308. My clutch was slipping pretty badly so I decided to replace it rather than trying to adjust it.

    Per the 308GT4 WSM:

    Thickness of driven plate without load: 9,2 - 9,5 mm
    Thickness of driven plate under load: 8,5 mm
    Wear limit of driven plate: 1 mm

    I read this as the new plate should be between 9.2-9.5mm and the disc is considered worn and "out of spec" if it's less than 8.2mm thick. My new friction disc is about 9mm thick (depending on where it's measured). The fried one I pulled out was 6mm thick. A difference of 3mm, or 3 times the wear limit. Hmmm...I think my clutch is worn out.
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  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,826
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #2 Steve Magnusson, Mar 9, 2010
    I think you've come to the right conclusion! ;)

    One problem with an exact number for the wear limit is that it implies 0.99 mm of wear is just fine and 1.01 mm of wear should be bad -- when it's way more "fuzzy" than that. I'd venture a guess that the designers learned that they were a little overly cautious with the 1.0 mm spec, and they just increased it on the later cars, even though the clutch design itself isn't much different. Also, the condition of the flywheel and pressure plate surfaces could get into it -- i.e., if you abuse the clutch and glaze the clamping surfaces, it might slip (badly) at less wear compared to a well-treated clutch with a lot of wear on the disc -- just a thought...
     

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