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LLOC-L-N-H-HLOC

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BorregoK5, Sep 16, 2001.

  1. BorregoK5

    BorregoK5 1/2 ton status

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    While out wheelin this weekend, I started playing around a bit with the transfer case LOC positions both low and high on various terrains to see which might apply best. Oddly enough, I loose more traction in LOC than without it from sandy hills on through rocky roads. Making turns downright loads the engine to a point I hope I don't get traction or something will snap. I have an open differential front and rear as of now which limits my overall climb as is. I expected a bit more out of the LOC positions. Anyone use the stock LOC enabled transfer case, any thoughts?

    What, Me Worry?
     
  2. BorregoK5

    BorregoK5 1/2 ton status

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    What, nobody else has a stock unit with these selections, or nobody uses them?

    What, Me Worry?
     
  3. Cmoe

    Cmoe 1/2 ton status

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    Mine works fine....you may want to check your gears in both front and rear for ratio difference....

    C'moe

    <font color=black>the blazer is "Back in Black"
     
  4. 6.2Blazer

    6.2Blazer 1/2 ton status

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    First of all, here's a quick explanation of what the different settings are. The 203 case has an differential (similiar to whats in a front or rear axle) that splits power between the front and rear axles and gives it the capability to be full-time four wheel drive and run on hard, dry surfaces without binding. This differential is basically open, so it can send all of the torque to either the front or rear axles. For example (for a truck with open differentials in the front and rear axles) if you jack the left front tire off of the ground, leaving the 3 others on the ground, the truck will not be able to move because all of the power is being sent through the path of least resistance which is the left front tire, which will just spin in the air, while the 3 others have no power being sent to them.

    When you shift into one of the LOC positions, it locks the differential inside the transfer case (kind of like an ARB locker) and will equally split torque between the front and rear. This means in worst cases, you would have one front tire and one rear tire with power. The problem with the LOC positions is that when turning, the front and rear tires follow different arcs which requires them to turn at different speeds to accomodate for this. The LOC positons does not allow a wheel speed difference between the front and rear so some of the tires will "scrub" or slip when turning.

    The "high" positions means that the overall gear reduction (torque multiplication) is not being changed in the transfer case. When shifting into "low", the gearing is reduced (or the torque is multiplied) by the low range ratio of the transfer case, which is about 2:1 for the 203. This will give you more low-end power and torque.

    In off-road situations, you should have better traction under all circumstances when in one of the LOC positions. As mentioned before, the tires might slip some when in LOC during turning so maybe that's what you are seeing. While it's not really recommended to run in LOC on hard, dry surfaces, you really shouldn't have to worry about breaking anything....especially if you are on dirt or gravel.
     
  5. BorregoK5

    BorregoK5 1/2 ton status

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    Thanks for running through the different scenarios. You've validated my understanding of what each of the loc positions are designed to do. I've verified my front and rear gear ratio to be the same before equiping the front driveshaft. Is there any reason I would slip more when climbing a hill in loc than without loc, especially when crawling slow up a sandy hill (it just doesn't make any sense to me). Could something else be interfering with proper opperation?

    What, Me Worry?
     
  6. 6.2Blazer

    6.2Blazer 1/2 ton status

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    There is no reason why the tires would be slipping/spinning more when shifted into LOC. Now if you were getting some sideways slipping of the vehicle it may make sense, but overall traction should be at least equal, but more likely greater, under all circumstances when in LOC.
     
  7. BorregoK5

    BorregoK5 1/2 ton status

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    Yes, most of the slipage was sideways slipage while travelling straight up. I took a few people up with me to my testing area today at lunch and had a few people spot both sides under both LOC and Open, high and low. The truck was more prone to spinning all 4 in LOC on the sandy hills and drifting left or right than without it. Strangley, it still seams to get up it a bit better without the LOC. I'm gonna throw a locker on the rear axle and try again. Perhaps this will all go away with 3 wheel drive!

    What, Me Worry?
     

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