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Clunk in driveline when pulling tranny out of Park....?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Greg72, Nov 28, 2004.

  1. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    It's a minor complaint, but every time I start the truck and pull it into reverse I get a substantial "BANG" which feels like driveline slop being taken up somewhere.

    The rear driveshaft is a nice High-Angle CV-style jobbie that's a few years old (but probably only has 5000 miles on it) there are no vibrations in the driveline at speed. The rear's got a Deeetroit in it, but this problem didn't seem to exist way back when that was swapped in.

    Could this be excessive play in the ring & pinion? Do Detroits get "looser" over time, or is this a classic symptom of a driveline that needs a new u-joint (or three?) /forums/images/graemlins/crazy.gif

    Idears?
     
  2. elacruze

    elacruze 1/2 ton status

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    Besides the obvious, I've seen vehicles with higher idle speeds (cams, poor tuning, etc.) bang really hard when the motor mounts are shot. Just something to look at.
     
  3. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    I doubt you have the awesomely popular slip yoke going into the transfer case; but if you do, I've read that pulling the driveshaft and greasing up the splines on the slip yoke will help. I've tried it and it works.

    I know I'm smarter than that knowing you wouldn't have something so poser, but maybe there's something in the drivetrain somewhere that just needs a little bit of grease........

    /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
     
  4. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    [ QUOTE ]
    I doubt you have the awesomely popular slip yoke going into the transfer case; but if you do, I've read that pulling the driveshaft and greasing up the splines on the slip yoke will help. I've tried it and it works.

    I know I'm smarter than that knowing you wouldn't have something so poser, but maybe there's something in the drivetrain somewhere that just needs a little bit of grease........

    /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif

    [/ QUOTE ]


    No slip yoke....just the standard 1972 issue NP205.
     
  5. 70~K5

    70~K5 1/2 ton status

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    Have you greased the slip in the rear driveshaft?
     
  6. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    get under the truck with wheels chocked and parking brake on. someone else in the rig to go from park to drive and then to reverse. if the d-shaft is moving slop in u-joints or ring and pinion. if the driveshaft isnt moving motor mounts or splines from tranny to t-case.

    im betting on a u-joint or its time to adjust your ring-pinion.

    i also keeping my fingers crossed for you that it isnt tranny to t-case, thats a lot of work for something so small that cna leave you so stranded /forums/images/graemlins/eek.gif
    grant
     
  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Greg, you do have a detroit back there, sometimes mine will do the same if the truck is at an angle. It is normal since the drivetrain becomes loaded when you parked it and the truck settles.
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'm betting it's a bad u-joint...

    Rene
     
  9. joez

    joez 1/2 ton status

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    U-joint, probobally the one on your pinion yoke.
     
  10. duece21

    duece21 1/2 ton status

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    mine does the same thing but pinion joint is just fine. But mine is in the T-case
     
  11. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    [ QUOTE ]
    Greg, you do have a detroit back there, sometimes mine will do the same if the truck is at an angle. It is normal since the drivetrain becomes loaded when you parked it and the truck settles.

    [/ QUOTE ]


    I agree with it being the detroit. My buddies bangs also. There will be more play at the pinion with a detroit, then if there was a standard diff.

    Oh and you dont adjust R&P play.
     
  12. MudFrog

    MudFrog 1/2 ton status

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    Mine started doing the same thing once I put a detroit in it. Probably that, if not I would say Ujoint.
     
  13. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    My C14FF Detroit has a good 25% rotation from "lock to lock". It can be very noticeable going from forward to reverse, especially if idle is up...
     
  14. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Would a Detroit get "looser" over time?

    Seems like it's been getting worse over the last 6 months..... the u-joint on the pinion end is a 1410, but I suppose when they go bad it doesn't matter how BIG they are.....
     
  15. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Not sure about that, I don't think it should change much, but no facts to base that on...
     

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