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Clunk, Clunk, Clunk, Clunk

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by johnny reb, Dec 18, 2000.

  1. johnny reb

    johnny reb 1/2 ton status

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    I've searched the archives but couldn't find anything specific to my problem.

    Was wheeling last weekend in 4HI. When done, I backed up 10' to unlock the hubs as usual (auto hubs). Seemed to unlock fine. Drove on highway for about 15 mins. at 65+ mph with no problems. Turned off ignition. Started truck 10 mins. later and began driving. As soon as I started accelerating, I had a consistent and hard "clunk, clunk, clunk" as the wheels turned. It felt and sounded as though it was coming from the rear. Stopped immediately, put it back in 4HI, went forward about 20 ft. (hubs locked up fine), took it out of 4WD and backed up. Problem solved.

    Haven't had it in 4WD since last weekend. But every once in a while I'll still get that "clunk, clunk, clunk" although not quite as hard. It only happens when I first start accelerating. To me it sounds and feels like it's trying to lock itself into 4WD, but not engaging all the way. Then it disappears. So, I repacked the front wheel bearings a couple days ago, and I had to replace the wheel bearing adjusting nut on the passenger side (the little pin had broken off).

    Could it be that it's trying to engage the 4WD? What should I check next?
     
  2. 85blaze

    85blaze 1/2 ton status

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    my dads old '83 with the auto hubs used to do that... we just took the hubs off and cleaned everything and it solved it. Or you could do what the rest of us have done, get some nice warn premium lock out's ;-)



    Finally done after 8 months.. Not really.. IM never going to be done. Stroker motor is next
     
  3. johnny reb

    johnny reb 1/2 ton status

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    I was planning on getting some Warn hubs, but I wanted to be sure that's the only problem. Thanks for the input.
     
  4. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    i would also suggest warn manual hubs also you will be more happy with them

    s.smith 77blazer lookin 4 mud
     
  5. johnny reb

    johnny reb 1/2 ton status

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    So you think if switch to manual hubs, that will solve the clunking that I'm positive is coming from the rear? Could the front hubs locking up be causing the clunking in the rear?
     
  6. Shawn

    Shawn 1/2 ton status Premium Member Author

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    It could be your rear 10 bolt!

    Shawn
    87 K5
    few mods[​IMG]
     
  7. johnny reb

    johnny reb 1/2 ton status

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    That's true. But I had the gears replaced about a year ago. And when they blew out, it wasn't a clunking noise I heard. I could actually hear the gears busting apart. And every time I made a sharp turn one of the rear wheels would look up. This "clunking" only occurs when I'm driving straight. Maybe I'll pull the diff cover and take a look just to make sure. Thanks
     
  8. backlash

    backlash 1/2 ton status

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    May not need to be said, but check out your u-joints!
     
  9. Thunder

    Thunder 3/4 ton status

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    Its those POS auto hubs. Its amazing how many horrible sounds they make when they start going out. Clunks, clangs clicks,vibrations ect When mine went out the noise sounded like it came from the rear, and the front, and the middle, Put manual hubs on and solved all problems
     
  10. riz

    riz 3/4 ton status

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    <font color=purple>I too think it's the hubs. Mine sounded like everything inside was exploding it was clacking so bad. I replaced mine with WARN premiums and solved the problem. Remember, with a lifted vehicle, the sounds underneath get swirled around and sound like they are coming from the rear when it can actually be the front. It's tricky some times to pin point a sound because of it. Does this make sense ? I had to lay on my dad's running boards once to zero in a noise his 84 pickup was making. It worked however, what sounded like the front was actually coming from the rear on this occassion. Until we did that, we would have bet our lives it was in the front. Weird stuff. Anyhoo, replace the hubs and you'll never regret it.</font color=purple>

    <font color=purple>L8r,

    .Riz.<font color=purple>
     
  11. K5Jimmy

    K5Jimmy 1/2 ton status

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    You may also wanna take a look at the tranny mount...could be just a coincidence that it dismantled itself when it did...that would account for the clunking sound at accelleration going away when ya get to speed...it may be binding the angle on the front U joint til everything sorta catches up to the torque applied at take off...it sounds like it is coming from the rear, and if it's bad enough, you can feel the vibration in your seat...could be a bad U joint also, but those tend to vibrate at speed if they are bad enough to make any noise at all...also, if a U joint is bad enough to "clunk", the sound tends to "ring" the driveshaft...I have broken several of "all of the above", so that's just what it sounds like to me...I've been rwong before...just sorta helping out with a list of things to worry about...good luck...JD
     

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