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locker or not to locker? What is a Posi?

Discussion in 'The Garage' started by 82GR8WHITE, Apr 19, 2003.

  1. 82GR8WHITE

    82GR8WHITE Registered Member

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    This question confuses the HE!! out of me so I will ask it to you guys. Assuming that Posi and Limited Slip are the same thing and that the other kind of differential is called an open differential... And that I have a posi/limited slip... What benefit would I get by putting in a locker? or are lockers for open differentials.Confused I am /forums/images/graemlins/rotfl.gif
     
  2. florida4x4

    florida4x4 1/2 ton status

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    Well lets start from the top...

    open differentials allow the tires to spin at different speeds. This is needed as you take a turn and the inner wheel will travel a shorter distance than the outer wheel. With an open differential if you stop your car with one tire on the grass and one on the road and floor it, the tire on the grass will spin like mad.

    posi is a generic term for a traction control device. There are several types and they all work differently but the overall effect they hope to make is to have power on acceleration delivered to both tires evenly. With one tire on the grass, a posi will distribute the power evenly and you will accelerate without as much wheel spin. There are two types of posi - limited slips and lockers.

    lockers - these devices use a mechanical locking action to absolutely eliminate differentiation under acceleration. during coasting they will unlock to allow wheels to spin at different rates around a corner. Serious off roaders use lockers in the rear axle pretty much exclusively. When used in the front they tend to straighten out the tires during acceleration so front locked axles require serious power assist to get the wheels to turn. Examples: Detroit Locker/No-Spin, EzLock, Lockrite, ARB, others.

    limited slips - These use clutches to regulate the power output. They will slip and allow a tire without traction to spin and are therefore not desireable for rock crawling. They work well in front ends in mud and sand because they allow you to steer more normally than a locked front end. The king of the hill in limited slips is the Precision Gear / Spicer Power-Loc. It uses a gear section that expands under power to compress the clutches tighter as more power is applied. Examples: Powr-Lok, Auburn, Trac-Lok, Truetrack

    So what do you choose? Well that depends on your driving style. If you are on the street 90% of the time and are mainly concerned with crossing speed bumps at the mall then save your money for neon running lights and keep the open differentals. If you are offroad most of the time or just want the best performance you need a rear locker. You also need to know that a rear locker can make the truck unstable when it disengages around a turn. In wet conditions, if you havent adjusted your driving style to the locker, the disengagement may cause you to loose gription and go slideways hitting another motorist. If you know what to expect you shouldn't have any problems. For the front you can install a locker and it wont change the way the vehicle handles as long as the hubs are unlocked. Lockers in the front are a poor choice unless you absolutely have to have the ultimate traction (rock crawling) because they dont steer well under power. In the mud and sand a limited slip is a better choice for the front because it allows some slippage so you can maintain directional control when you floor it.

    Hope this helps /forums/images/graemlins/tongue.gif
     
  3. heavy4x4

    heavy4x4 1/2 ton status

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    Excellent post. /forums/images/graemlins/laugh.gif /forums/images/graemlins/thumb.gif
     
  4. HarryH3

    HarryH3 1 ton status Author

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    Good explanation, except the last one on this list: [ QUOTE ]
    It uses a gear section that expands under power to compress the clutches tighter as more power is applied. Examples: Powr-Lok, Auburn, Trac-Lok, Truetrack


    [/ QUOTE ]
    The Truetrac doesn't have any clutches. It uses a set of worm gears in the case to bias torque between the axles. There's a picture and a brocure available at: http://www.tractech.com/Products.htm#slip /forums/images/graemlins/thumb.gif

    Another interesting traction aid is the Zexel Torsen differential. It also uses an array of worm gears to bias torque between the axles. I've got one in the rear axle of my S-Jimmy. It has no unusual manners at all. The truck drives as if it has an open diff in the back, except it never slips a rear tire, even on gravel, snow/ice, etc. There's some interesting info on the Torsen at http://www.torsen.com/products/T-2.htm You'll also find Torsen diffs in the origial Hummer. /forums/images/graemlins/cool.gif The one used there is the Torsen T-1, which can be seen here: http://www.torsen.com/products/T-1.htm

    The Torsen is a really slick unit that operates so smoothly that you don't even know it's there. But it, and the Truetrac, do not get along well with tires over 33 inches tall. The Torsen is capable of handling up to 600 HP. However, it seems that when the tires are very tall, and used in hardcore offroad situations, the leverage that they have to push torque back into the differential overloads it in a most spectacular fashion. /forums/images/graemlins/eek.gif /forums/images/graemlins/frown.gif I'm not sure of the power ratings on the Truetrac, but it also will self destruct when used with big tires.
     
  5. 69K5

    69K5 1/2 ton status

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    so how do ox lockers fit into here??

    nathan
     
  6. 82GR8WHITE

    82GR8WHITE Registered Member

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    Hey Thanks Guys.
    That really clears up alot of my confusion. /forums/images/graemlins/smile.gif Most of my wheeling is on/in the sand at the beach. /forums/images/graemlins/thumb.gif Not many rocks around here. Any suggestions for sand?
     
  7. florida4x4

    florida4x4 1/2 ton status

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    Ox is a mechanical locker that is cable operated. Apparently they are a real pain to engage, the cable is stiff and almost unroutable so you might be better off with the tried and proven ARB which is engaged by air pressure. Plus I thinks Ox is out of business...
     

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