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posi??????

Discussion in 'General Chevy & GM Tech Questions' started by k/4x4/93, May 24, 2010.

  1. k/4x4/93

    k/4x4/93 New Member

    How can i get my rear end to have full time posi? can i get some tips or links please??
  2. MrShorty

    MrShorty Moderator Staff Member 1000 Posts 100 Posts

    The hardest part of answering a question like this is what do you mean by "full time posi"?

    As I understand the history of the term, "posi" originated as a GM term for a clutch or a cone type limited slip. It seems to have evolved to include all differential types except the conventional "open" differential. The usual options:

    1) Clutch type limited slip: this is a full time (as in it is always engaged) unit that uses clutches to limit how much the wheels can slip. Limited slips work well as long as both tires have some traction. In a case where one wheel has no traction (think one wheel hanging in the air), a limited slip may not transfer enough torque to the wheel with traction to move the truck. The clutches also do wear out over time, so they need to be replaced periodically.

    2) Geared limited slip. Similar in operation to a clutch type limited slip, only it uses gears rather than clutches. The main advantage is that, without clutches to wear out, it doesn't need to be rebuilt like a clutch type LS.

    3) Eaton G80 (GM's factory "posi" since at least the '80's). Not really a full time unit, in that it only engages when needed, and then only below 25 mph or so. More of a locker when engaged in that you get a solid lock between the wheels so that one wheel can't spin without the other.

    4) Auto locker (like a Detroit locker or your "lunchbox" lockers). These are also "full-time" in that they are normally locked, with a ratcheting mechanism that allows the wheels to differentiate when cornering.

    5) Selectable locker (ARB for example). This is what I put in mine. Not really "full time" because it is normally off. When turned on, you get a solid lock where the wheels have to turn at the same speed.

    6) Spool. The most "full time" option, in that it permanently locks the axles together so there is no mechanism for differentiation. Not really suited for everyday driving, but they can be a good option for a dedicated trail rig.

    Those are the usual options. What are you looking for?
  3. 2COR517

    2COR517 New Member 1000 Posts 100 Posts

    The Eaton Tru-Trac is a solid differential for your truck. Eliminates the weak factory carrier, un-noticed on the street.

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