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Heavy driveline clunk after install of NP203 part time kit.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 79ChevySB, Aug 10, 2002.

  1. 79ChevySB

    79ChevySB 1/2 ton status

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    Well today I installed MileMarkers part time kit(#501) in my NP203. Everything went together fine, didnt loose any of the needle bearings on the install. When I backed out of the driveway there was a good clunk in the drivetrain. When I drive it around town and I come to a stop it clunks again. Then it clunks when I drive off. I let my foot off of the brake pedal to take up some of the shock, but there still is a clunk.
    Could the driveshaft be shot? We checked it today after the install and it seemed tight.
    The instructions for the MM kit say that you should have some play in between .010-.050 how do you check this with a feeler guage? We had almost no play at all, barley moved.
    Think it could be shot tranny mount or motor mounts?
    Thanks guys.
     
  2. HarryH3

    HarryH3 1 ton status Author

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    My vote is for the slip-joint in the rear driveshaft. When it was full-time, both driveshafts shared in acceleration. Now the back one has to handle the chore alone. Try lubing the splines up really well and see if it helps. If the splines are sloppy you'll need to have them replaced soon. /forums/images/icons/frown.gif Sometimes you can have someone lay down next to the truck (safely out of the way of the tires!) and watch the driveshaft. If the splines are binding, the driveshaft will really jump when the rear diff rotates upwards on takeoff.
     
  3. 76chevy

    76chevy 1/2 ton status

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    That sounds right to me too. I have a major clunk if I remove the front driveshaft, esencially the same thing the part time kit does, because all of the force is now on the rear shaft.

    To check the shaft, apply the parking break, block the wheels and shift your transmission into N and your transfercase into N also. You will be able to feel the slop by rotating your driveshaft by hand from under the truck. Another thing to do is shake it. If it moves at all where the slip yoke sits on the driveshaft it is in need of repair. Possibly the teeth on the driveshaft also.
     
  4. 79ChevySB

    79ChevySB 1/2 ton status

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    Thanks for the ideas guys, I would have never thought of lubbing the rear shaft, but I'll give it try.
     
  5. 79ChevySB

    79ChevySB 1/2 ton status

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    I forgot to ask this but should there be a little play in the drivetrain, or should it be pretty tight all the way through? Again Thanks.
     

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