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Hub Lock

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bking, Jan 8, 2001.

  1. bking

    bking 1/2 ton status

    Jan 4, 2001
    Likes Received:
    Alaska /Here from Ireland in Dec 2000
    ok ok, I'm new to a K5, can someone please explain to me about the front hubs. When or why would I lock them? At the min it's snowing and icy here, the hubs are locked all the time, is this right? Sometimes when trying to turn sharply into a parking space the whole front end jumps, is this because of the hubs being locked? Just doesn't like turning sharply, someone please explain the hub thing to me.
  2. mudhog

    mudhog THEGAME Staff Member Super Moderator

    Nov 6, 2000
    Likes Received:
    portland oregon
    when or why would you lock them? well you need to lock them when you want to use 4wheel drive if you do not lock them you can put the t-case in 4hi or 4low but you will not have any power at the front wheels untill you lock the hubs. when snow or ice is present you can leave your hubs locked and shift your t-case into 2hi and when you need 4x4 you can just shift into 4hi or 4low without getting out and locking the hubs i would not do this all year just during the winter months or bad weather

    s.smith 77blazer lookin 4 mud
  3. Goose

    Goose 1/2 ton status

    Feb 17, 2000
    Likes Received:
    South Central Kansas
    Yes, turning sharply in 4x4 on surfaces with traction will cause your front end to jump around on you. In 4x2 power is just sent to the rear. When you put it in 4x4 power is split 50/50 front and rear by your transfer case. However, you still have to lock in your front hubs to get the power to your front tires. The locking hubs are just a gearset that engages the drive axle to the front hub assembly. As for the jumping. When you turn, each tire has a different turning radius and therefore travels a different distance. This is why rear ends have a 'differential' to account for the different radii on turns. The front end also has a differential. This takes care of the difference between individual rear tires and individual front tires. The problem is that the transfer case doesn't have a 'differntial' to account for the difference between the front tires as a whole and the rear tires as a whole. You get what is call 'driveline binding'. The jump is when this tension is releived by the front tires sliding across the ground. That is how a NP205,NP208, etc. works....
    A NP203 is different because is does have a differential in it.(no pun intended) In 'high' or 'low' power is sent to the front and rear but not at 50/50. It's sent to whichever axle has the least traction, just like a differential in the rear of the vehicle with one tire spinning. When you put it in 'high lock' or 'low lock' it locks the differential mechanism in the transfer case together so the power is truely split 50/50 front and rear. The NP203 case also came without locking hubs because it's a full time 4x4 system. They have driven hubs. There is no provision to lock or unlock them. If you have locking hubs, then you don't have a NP203. (unless someone converted it to part time 4x4, in which case it works like the other transfer cases)


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