gm 8.5" posi unit rebuild or replace?

Discussion in 'Camaro Questions' started by 71RS6SPD, Oct 10, 2017.

  1. 71RS6SPD

    71RS6SPD Veteran Member

    Nov 14, 2016
    Thanks I found them Part #C12-PSS. Is there any way to measure the clutches to know if they are worn out? Tom doesn't run the springs at all? I thought that they were left out just for the setup procedure. Mine does have the single S spring.
  2. jthomas

    jthomas Veteran Member Lifetime Gold Member

    Dec 5, 2007
    NorthCentral PA
    To see if the clutches are worn check the axle end play. Put a dial indicator on the face of the axle. Push the axle in all the way and then pull it out. What is the reading? .005 is the minimum and new clutches can be .008 to more. Once the differential has a lot of miles on it, the clutches wear and end play gets larger. I've seen .060 and more. If you have much end play I would replace the clutches since you are in there. When you pull it apart check the clutch plates for wear marks and hot spots. You'll be able to tell. If it were me, for the small cost, I would just replace the clutch packs on each side.

    As for the spring, Tom does not reinstall. I do. Just put the S spring back in when done.

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