Lost all gear oil today, 1991 Testarossa

Discussion in 'Boxers/TR/M' started by PA32Pilot, May 9, 2020.

  1. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    southwest germany
    Full Name:
    romano schwabel
    on road and off road? then you need other tires and other suspension to go off road ;)
    paulchua and Natkingcolebasket69 like this.
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  3. paulchua

    paulchua Cat Herder
    Moderator Owner

    Jul 1, 2013
    Menlo Park, CA
    Full Name:
    Paul Chua
    Trail rated baby...and wouldn't be the first time!
  4. ferralc

    ferralc Formula 3

    Sep 2, 2010
    San Diego CA
    Full Name:
    Jamie Hi I PM’d you as well for the spreadsheet thanks in advance

    Sent from my iPhone using Tapatalk
  5. mexicruiser

    mexicruiser Karting
    Silver Subscribed

    Aug 28, 2012
    25oN 100oW
    Full Name:
    Jon Brinckmann
    That 1.55mm shim is the size I need! Still have it? Sent you a PM
  6. mexicruiser

    mexicruiser Karting
    Silver Subscribed

    Aug 28, 2012
    25oN 100oW
    Full Name:
    Jon Brinckmann
    I know the car is fixed but others might read the thread later so I thought I would post some extra info as I also share Dominicks opinion/doubts on the preload subject.

    I’m installing my new diff in the boxer and have been chewing on this because my new diff is larger and requires new shims.

    After removing the crown on my old diff I put it back in with the case on its side and measured the gap on the RH cover, this was .070-.072” and having a .051” shim amounts to a .020” preload.
    I did the same with the new diff and the gap is .080-.081” (.010” larger diff) so in order to maintain the same preload I need a .061” shim.
    To test this I did what Versamill suggested and cut a paper shim from .0095 thick paper, due to lack of the original tool for a more precise measurement I tried both newmans “turn tight without squinting” and Turbo-Joe string around the carrier methods, Result: the carrier was barely movable by my hand on the output flange and using a string 7Kg where needed to spin it (helping it start of course), I also measured 5Nm to maintain spin with a small torque meter on the flange nut.
    I increased gap RH until I got 2.5kg to spin, for this I had to increase an additional .017”, at this point turning the diff by hand could be done with my fingers on the flange and required torque on the flange bolt was 1Nm, it just feels too loose and no wonder as it is only a .003-.004” preload on a wide aluminum case, for comparison a Dana 44 spec is .015” on a robust iron case/axle housing.

    Perhaps the 4:1 gear reduction plays a role to get the 3.6 to 4.0 kg the manual states? My 7kg divided by 4 (gear ratio) is 1.75kg plus 1.8-2kg for the pinion bearing preload. Coincidence?
    Too little preload can cause the pinion to ride on the edge of the crown and fail, I wonder how much of those 7kg are left after the case heats up to operating temp. I wish I had made the string test on my old diff before I removed the bearings , this would have given us an additional benchmark.
    Undecided still but I’m leaning towards adding the .010” to maintain previous gap and preload or at leas close to that.
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  8. MOSS

    MOSS Formula 3
    Rossa Subscribed

    Apr 28, 2004
    So sad to see Shamile no longer posting on Fchat

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