Locker VS Posi

Discussion in 'Performance' started by BlueTahoe2001, Dec 25, 2009.

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  1. BlueTahoe2001

    BlueTahoe2001 Full Access Member

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    Ok, I have heard a lot of information about both lockers and posi units for the rear of our trucks.

    I have some questions concerning both. For a locker- I know it's more off-road but I love the way my Fathers 78' Camaro drives with a locker. That thing doesn't miss a lick and seems like it still rides really well on the road despite the fact it is a locker. Doesn't have a ton of wheel hop but does have some.

    For a Posi unit- What's the difference between this and a locker? I am assuming that a Posi locks when needed and is unlocked when it's not? I have also heard you don't get the wheel hop you do of a locker?

    Let's hear some opinions on this. Not sure which to go with yet but almost leaning toward a locker because of the Price over a Posi unit. Something like a Power-Trax because I can get them for $259.00.
     
  2. rob71

    rob71 TYF Newbie

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    Posi is a trade name for a limited slip differential; the automakers all have had different names over the years for limited slip - Posi-traction, Sure-Grip, etc...

    A limited slip differential has the same internal gears as a normal open differential but also has friction clutches that can transfer power to both wheels when one wheel loses traction. The clutches are set up to slip a certain amount to allow normal differential action - that's where the left and right wheels have to turn at different speeds when you're turning a corner or going around a curve. The down side is that in extreme conditions (climbing up over slick rocks, or off roading where you lift a rear wheel of the ground - neither of which are likely situations for a Tahoe or Yukon) the clutches may not transfer enough torque to actually get the vehicle moving.

    Lockers are more aggressive and have a locking mechanism like a ratchet between the left and right sides. They're great in severe offroad conditions like rock crawling, but if you drive in winter weather (ice, snow, even sometimes just rain) they can make the vehicle handle really unpredictably.

    I've had vehicles with both types and I wouldn't have a locker on a street driven vehicle again unless it was really smooth acting. The abrupt ratcheting action of the aftermarket locker that was in the 14 bolt rear on my truck was unpleasant on the curved street I used to live on, and the rear end would kick out in turns in the wet weather. I used to live on a circle and I'd have to let off the gas about five times to let it unlock and get around the circle.

    I don't like lockers on street driven vehicles - they're great for offroad though. That's just my opinion, take it for what it's worth. Today I was driving in about four to six inches of snow on the roads and I need predictable cornering, so a locker is out.

    I have had limited slip differentials that were so tight they'd chatter in slow turns and people thought I had a locker ('89 Caprice police car for one), but it was just that the friction modifiers in the gear oil were all used up. I had a Porsche that would burn up the friction modifiers in about 2,000 miles and the diff would start groaning in slow turns until I changed the transaxle oil again.

    The stock Gov-lock on these trucks is a bastard hybrid that should never have been sold - the limited slip clutch action is too weak, the case is too weak, and the locking mechanism is too weak. I'm looking forward to replacing mine with a normal clutch or cone style limited slip in the spring. You can pick up a good limited slip differential for around $400 these days, and that's not bad for what you get.

    That's all my opinion, but it's up to you what you choose - it depends what you want to get out it.
     
    B2sdad and David Paul like this.
  3. Sasquatch

    Sasquatch Full Access Member

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  4. pmbiker

    pmbiker Member

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    The link above is addressing wheel hop caused by straight line acceleration. The wheel hop were talking about is when the inside wheel hops going around a corner with a locker. That is due to the inside wheel going a shorter distance around the corner thus causing a bind.
     
  5. Sasquatch

    Sasquatch Full Access Member

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    oh, ok. i`ve only known one version of wheel hop and thats the one in the link. thanks for clearing that up.
     
  6. Max

    Max Mile High

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    I prefer the detroit tru trac helical limited slips in these 10 bolts, much smoother transition and less stress on parts.
     
  7. MOBmentality

    MOBmentality Has a $25,000 Punch Supporting Member

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    i agree with rob.. definitely would rather just run posi on the street.. but if i was that set on having the rear end lock..
    i would honestly rather just deal with the wear and tear of a spool than i would the unpredictability of lockers. at least then you KNOW its gonna chirp on tight corners and stuff.. and not have to toss a coin each time
     
    Last edited: Jan 1, 2010
  8. rucr8z2

    rucr8z2 Full Access Member

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    Everyday driving get a posi unit or a electric locker(turn on when you need it)
    Don't get the powertrax its just a replacement for the spider gears and its clicking got on my nerves badly!!!!!!!!!!!!! ( but easy to install though)
     
  9. BOSS

    BOSS The People's A D M I N Supporting Member

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    Great information, keep it coming - gunna stick this one

    B
     
  10. rucr8z2

    rucr8z2 Full Access Member

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    The Tru Trac is the Factory limited slip on Dodge trucks.
     

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