4WD trouble

Discussion in 'Trucks and Trailers' started by Silver7, Jan 21, 2001.

  1. Silver7

    Silver7 LawnSite Member
    from PA
    Posts: 10

    I just bought a 1988 GMC stepside Z71,automatic,350. I am having trouble with the 4wd. It shifts into 4wd, but when I start to drive I can feel it pop out of 4wd and into 2wd. It does this in 4wd high and low. Sometimes I will shift into 4wd, but the front gear box won't engage. If I shift into 4wd low and high a couple of times, it will eventually kick into 4wd. Any suggestions on what cause be causing the problems? Thanks!

    Josh
     
  2. 4x4k20

    4x4k20 LawnSite Member
    from ga
    Posts: 148

    sounds like the front axle actuator is bad they give lots of trouble if you need one buy a aftermarket one such as one from rancho. it is located on the front right axle tube it has 2 wires going to it if you dont know where it is.
     
  3. Silver7

    Silver7 LawnSite Member
    from PA
    Posts: 10

    After doing some reading, it turns out these thermal axle actuators are a real POS. The options I've seen so far are:
    1. Replace with new thermal actuator
    2. Replace with vacuum actuator
    3. Replace with servo controlled actuator (not sure if this can be done)
    4. Replace with manual controlled actuator

    What is everyone else doing out there and why?
    Thanks!

    Josh
     
  4. mike reeh

    mike reeh LawnSite Member
    Posts: 229

    i think a few months back, petersens 4wheel mag did a conversion which eliminated the actuator.. i dont think they changed the t-case, but i think the hubs were changed.. if you're really interested i can probably dig it up..

    mike reeh
     
  5. Silver7

    Silver7 LawnSite Member
    from PA
    Posts: 10

    I ended up getting the late model (97 and up) electric actuator. It's partially installed right now. Everything is hooked up except for the wire which is supposed to be wired to the 4wd signal wire just above the transfer case. Does anyone know which wire that would be? (There are 4 wires, black, blue, purple, and yellow.) It seems like the easiest solution right now. If this fails, however, then I'm going with a manual actuator or possibly eliminating it all together like you mentioned. Would this elimination kit involve going with locking hubs to engage 4WD? If not, how would 4WD be engaged with this elimination setup?
    Thanks!

    Josh
     
  6. MTCK

    MTCK LawnSite Senior Member
    from Idaho
    Posts: 254

    I think I remember the article that Mike is talking about. It's a manual lever that goes under the dash, and you pull it out and turn it to engage the axel just like the electric one would, but with a cable. As far as finding the right wire, get out the multi-tester. See which wire goes hot when you pull in the 4x4. That's your wire. Good luck.
     
  7. wyldman

    wyldman LawnSite Member
    Posts: 182

    Just a thought,but if you are connecting that actuator to the 4WD signal wire,just make sure the switch can handle the current,and you use decent size wiring.A relay would be a much better idea.
     
  8. Silver7

    Silver7 LawnSite Member
    from PA
    Posts: 10


    I have seen the posi-lock system ($149 from JC whitney) you are talking about. This doesn't get rid of the actuator though, it just converts the system to a manual type actuator instead of an electrical or thermal actuator. It doesn't require hub replacement either. Is this the system you were referring to Mike?

    The wiring harness to adapt the newer type actuator was purchased at the dealer. All the wiring needed to complete the job is included in the kit. I don't think a relay will be necessary and even though the wire isn't what I would call heavy duty, I am assuming it will handle the current.

    Josh
     
  9. 4x4k20

    4x4k20 LawnSite Member
    from ga
    Posts: 148

    what are yall talking about locking hubs ? i never have seen a 88to present gm with ifs that had locking hubs
     
  10. Silver7

    Silver7 LawnSite Member
    from PA
    Posts: 10

    I was referring to Mike Reeh's post where he mentioned there is a 4WD kit that replaces the actuator and may involve changing hubs as well. I have not seen any kits that involved changing hubs, that's why I was asking. Maybe he can find the article he saw and let us know the deal on this kit.

    Josh
     

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