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Clunk when putting in gear

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Sparky, Jan 7, 2001.

  1. Sparky

    Sparky 1/2 ton status

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    I get a nasty clunking noise when I put my truck in gear. Espessialy reverse. I just put the part time kit on my NP 203, and that seemed to increase the problem. I am pretty sure it is the rear axle because last time I took the rear drive shaft off there was alot of play when I turned the U joint on the axle by hand. Dont really remember, but I thing it was about an 1/8 of a roation before It would actually move the axle shafts. It also does it when I am driveing if I coast for a minute and then get back on the gas. What causes this problem and is it something I can live with or am I going to have to replace the rear axle soon? Also, I could not feel any play in the transfer case, but could a stretched chain on the 203 cause the descriptoin I gave? Thanks again?

    Sparky

    When all else fails... Check the blinker fluid.
    78 K-5
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    It sounds like a bad U-joint to me.

    Rene

    [​IMG]
     
  3. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    Sounds like u-joints. A little free advise. Spend a little more and buy the good heavy duty ones..

    [​IMG]
     
  4. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    sounds like u-joints to me also

    s.smith 77blazer lookin 4 mud
     
  5. Bigmeats

    Bigmeats 1/2 ton status

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    DITO

    Bigmeats

    Carl...75 Blazer...Manhattan IL
     
  6. BillyBob

    BillyBob 1/2 ton status

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    Yeah, that clunking noise was what I had before my driveshaft fell out! Definately invest in some U-joints. I learned the hard way... Refurbashing a driveshaft ain't cheap! I'm $160 poorer!
    [​IMG]

    <A target="_blank" HREF=http://billybob.coloradok5.com>http://billybob.coloradok5.com</A>
    It's all fun 'n games, till someone gets stuck.
     
  7. ftn96

    ftn96 1/2 ton status

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    Ditto on the u-joints. But there is slack in the rear end. And you will get that until you rebuild the rear end. The u-joints will help with the slack you have in the driveshaft. But there is still going to be some slack in the rear. Mine does the same thing.

    Will work for parts, beer and sex.
    90 Jimi,350/700R4/241/10bolts/3.73's/33's/4"
    <A target="_blank" HREF=http://mccordhouse.freeservers.com>http://mccordhouse.freeservers.com</A>
     
  8. Sparky

    Sparky 1/2 ton status

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    I'll buy the U joints and replace them. If that does not solve the problem it must be the rear end right? If that is the case should I let it go or do I need to rebuild the rear axle? New axle shafts? new spider gears? new ring and pinion?

    thans again
    Sparky

    When all else fails... Check the blinker fluid.
    78 K-5
     
  9. ftn96

    ftn96 1/2 ton status

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    It will just gradually get worse over time. It's just something you'll have to get use to or you can splurge and get a new ring and pinion and spider gears. You may want to replace the axles while your in there. But it all depends on how they look when you pull them out. The spider gears are most likely the culprit though. If you get yourself a different differential unit, like an Auburn Limited slip or something like that should do the trick or you can replace the spiders with a locking unit. Just depends on what kind of wheelin you do. Im replacing my ring and pinions and my carriers (spider gears) with Aurburn limited slips in the front and the back.

    Will work for parts, beer and sex.
    90 Jimi,350/700R4/241/10bolts/3.73's/33's/4"
    <A target="_blank" HREF=http://mccordhouse.freeservers.com>http://mccordhouse.freeservers.com</A>
     
  10. BigTex

    BigTex 1/2 ton status

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    Whoah, Sparky. I wouldn't rush to change the U-joints just yet. I have THE EXACT SAME PROBLEM on my '79 with the NP203 and the part-time conversion kit as well. Mine does it very loudly whenever I put it in gear (especially reverse) and when I let off the gas as I am about to stop. This was before AND AFTER I installed the part-time kit. I also changed all the u-joints because I also thought it was the U-joints but the problem persists to this day. I don't know if it is a problem as I have talked to some shops and was told that unfortunately this was normal on trucks with the NP203. To tell you the truth, I had already accepted that fact and have learned to live with the nuisance, but who knows? I wonder if anyone else has had this problem. I'll tell you what: I know what bad u-joints sound like and this does not sound like bad u-joints to me. Especially after they have all been replaced. I would like to know how everything turns out. Good luck. How about it guys, has anyone else experienced this loud clunk?!!!
     
  11. Blue85

    Blue85 Troll Premium Member

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    I think that these results are to be expected. Some clunking is normal from worn U-joints, but it is also common for clunking to come from an aged rear end. It comes from the ring and pinion, yes, but even more so from the spider gear assembly. The reason that you notice it more after converting to part-time is that all of your torque is going to the rear end. In 4WD, there are more gears and more inertia and a tight front-end may unload the kick from the tranny before the rear end has a chance to clunk. With my NP208 in 4HI, I don't get any clunking when I drop it in gear. In 2HI, the familiar old clunk is back.

    I minimized my clunking by doing the following:
    -new Ujoints in the rear driveshaft, greased every couple of months.
    -swapped my "more worn" cross-shaft and spider gears in my front differential and moved the "less worn" gears to the rear end.
    It actually doesn't make much noise anymore, which leads me to believe that the spider gears are responsible for the majority of the clunk. I can only imagine how much better it would be with new spiders! Of course, with a 203, you probably have D44/12Bolt, so you couldn't swap spiders, but new ones or a case-replacing locker/LSD would probably solve almost all of your problem. That's just my guess, though, you'll probably have to open the diff and see if there is any slop in the ring and pinion.

    <font color=blue>Powered by a Goodwrench 4-bolt longblock [​IMG]
    240hp...for now.</font color=blue>
     
  12. Todd78/87

    Todd78/87 1/2 ton status

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    I agree with BigTex,, I have a 78 with a brand new rebuilt 203 with the part time kit,, new rebuilt tranny, new drive shaft with new u-joints and new gears in the rearend. Mine clunks pretty good going into rev. also. I just turn my idle way down [​IMG]

    Todd 78/87[​IMG]
    [​IMG]
    Haines,Alaska
     
  13. chevydude

    chevydude Registered Member

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    i just rolled a 14 bolt ff under mine and it has a severe clunk in it i will be tearing it apart soon to replace the spider gears that seems to be a common problem with all gm corporate rear ends


    marcus
     
  14. coopertwpk

    coopertwpk 1/2 ton status

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    Minehad a clunk like your it turned out to be the mount ,It had stripped the nuts and was shifting around .

    88k5 silverado w4"lift soon to have <font color=orange>d44 and corp14ff</font color=orange> with 4.56s
     
  15. HarryH3

    HarryH3 1 ton status Author

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    New spider gears? Why not go ahead and put in a locker while you have it apart? [​IMG] Of course, it will really clunk then! [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
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