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rear end "clunk" question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Neil, Sep 9, 2001.

  1. Neil

    Neil 1/2 ton status

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    rear end \"clunk\" question

    what causes a rear end to clunk when put in forward gear or changed to reverse gear. It is a 79 K10 SWB 350/TH350 4x4 farm truck. Also when the brakes are applied, the truck naturally slows then, but then a clunk hits when the truck comes to a complete stop. when you start to go again, the clunk hits again. Is this a loose axle, driveshaft play, or what? Anyone ever have this happen? It feels like the truck has been rear-ended by an army tank when it clunks!

    Neil H. Alabama.. '78 K5 400ci 4x4 AT,AC,PW Cheyenne., '74 C10 4x2
     
  2. hammer

    hammer 1/2 ton status

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    Re: rear end \"clunk\" question

    check the pinion nut is it loose. Have you done any thing to the rearend lately?
     
  3. MudNurI

    MudNurI 1/2 ton status

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    Re: rear end \"clunk\" question

    Everyone automatic full-size Chevy I have ridden in/driven, from a 85 up to hub's 99, does the same thing, It is NOT as bad as you are discribing yours, doenst feel like an army truck hit ya, but after numerous bouts with my dealer- with our 89, we were okay with the "it's just play in the rear end" reply. We have not done ANYTHING to the 89's rear end.., and to this day with onver 300k miles, it still does it. LIke i said, its not as bad as yours, but a normal clunk is, one thing to make sure specially with how WELL gm makes there tranny's STOP before shifting from D-R or R-D. We did replace two in the 89, anyhow, I think its normal.. but then again, I have been wrong before. I would have it checked.

    1986 K5 4" skyjacker suspension 3 " body, 14 bolt rear,(sitting next to truck) 12 bolt (still in truck) dana 44 front, TIRED ol 305----
     
  4. RedDwarf

    RedDwarf 1/2 ton status

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    Re: rear end \"clunk\" question

    Later auto trannies have an auxliliary valve body that keeps them from clunking. I think that came around in the early 90's.

    Lift It, Lock It, LIVE IT!!!
     
  5. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: rear end

    Pull the driveshaft. De-burr the output shaft on the trans, and check the yoke on the shaft for debris and any other crap hat would make it bind. Then apply some white lithium grease to the splines on the yoke. My 88 P/U did this, and the dealer showed me the trick after they charged me $300. BASTARDS!

    Let me know if this helps at all.... What happens it that the brakes on the back of the truck wear out, and the rear diff drives the yoke onto the output shaft REALLY HARD, and it sticks. Then once the truck stops, the weight settles, and the yoke goes BANG! back off of the output shaft, the rear axle moves backward (the army truck I suspect) and things are happy again. It might also stick until you leave from a stop.


    <font color=red>GOT MUD???</font color=red>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a>
     
  6. Highlander

    Highlander 1/2 ton status

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    Re: rear end \"clunk\" question

    I was going to say the u-joint but now I'm not so sure.
    I know that my tranny shifts hard up and down but it doesn't clunk. Good luck Eric

    <a target="_blank" href=http://cethern.tripod.com/erics-home-page-and-other-stuff/>http://cethern.tripod.com/erics-home-page-and-other-stuff/</a>
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  7. Neil

    Neil 1/2 ton status

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    Re: rear end

    I looked and it didn't appear that the driveshaft/rear yoke was greased at all. I know the rear driveshaft was replaced because it had got bent. If they didn't grease it when they replaced it, could this be a problem? Is there a way to prevent it from sticking and settling in the rear besides replacing a yoke? Thanx.

    Neil H. Alabama.. '78 K5 400ci 4x4 AT,AC,PW Cheyenne., '74 C10 4x2
     

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