348 transaxle questions | FerrariChat

348 transaxle questions

Discussion in 'Technical Q&A' started by spider348, Jan 31, 2004.

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  1. spider348

    spider348 Formula 3

    Nov 3, 2003
    Full Name:
    Question for those far more knowledgeable than I.
    I posted some time ago regarding a bearing failure in my 348 spider transaxle.
    Have stripped the trasnaxle down and determined the bearing that failed is the roller bearing that supports the input shaft midway between the clutch and the crankshaft.
    In the parts manual #131049/138341(#21 in the view)
    Thinking a total failure of this bearing somewhat odd, I am attempting to determine root cause of failure.
    I believe a part of the cause is positioning of my input shaft too far toward the clutch.
    I mounted my now empty gearbox on my motor, installed the input shaft and the clutch assembly. Reaching through the empty differential port I could move the shaft 5mm+ in either direction. I believe 5mm+ is in excess of correct allowable movement.
    Measuring the relative position of the input shaft at various locations I noted that with the shaft forward the input shaft OD/inner race is positioned correctly in the center of the roller bearing. With the shaft back 5mm the input shaft OD/inner race is partially out of the roller bearing contact surface. I believe this could result in the roller bearing collapse.
    My questions:
    How much movement with axis is acceptable for the input shaft?
    How is this movement controlled? Spacer?
    Thanks for the help.
  2. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    Try it again with the snap ring on the clutch side of the input shaft next to the three input shaft seals. Snap ring prevents movement toward engine. Cutout in FW prevents movement to Bellhouse. Input shaft supported fore and aft. Center bearing to control harmonics only. Very little force here so those bearings are not doing much. ASk your dad about "Steady rest" for a lathe.
  3. spider348

    spider348 Formula 3

    Nov 3, 2003
    Full Name:
    Good point Fatbillybob, the snap ring was not in place. I will measure and see if the problem still exists.
    Saw my father this AM, he is from the "steady rest" lathe era. Unfortunately, I think all too much in the current CNC era. Craftsmen are vanishing from the landscape! Sad.

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