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scratching my head

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by prjt_blzr, Oct 26, 2001.

  1. prjt_blzr

    prjt_blzr 1/2 ton status

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    COS, CO
    My K30 has developed the death wobble again now that it is getting colder outside. When I hit a series of bumps or occasionally hit the brakes the front end of the truck goes into a SEVERE wobble. I have to peg the brakes to slow the truck down to stop this. The front end of the truck feels like it is about to come apart.

    The rotors have about 0.003" of runout. Tie rods and drag link are tight (and almost new). The king pins have new nylon bushings, springs, bearings etc. The steering damper is tight. I have new bushings in the springs and an ORD steering box brace. The alignment is good. I've had several sets of tires on the truck and they all do it. My 35s will do it more often than 265/70R16 trailer tires will. The bearings are tight and I can not force movement anywhere with the truck on jack stands. The alignment shop is also baffled.

    I'm at a loss as to why this is happening. Is it possible that the steering box or hydro boost is causing this or ???

    Thanks,

    Mike
     
  2. four_by_ken

    four_by_ken 1/2 ton status

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    This is for me with 39.5s. I had the same problem when I went to the larger tires. I did all the checks you did.

    What fixed mine was... My steering stablizer was a little old, but still fine. But, I replaced the one, with two brand new ones. The new ones were a lot stiffer than the old one I had. So, maybe my old one wasnt as good as I thought it was.

    100% differance. Not a bit of wobble at all. Dont get the real cheap ones though. I got the two stabalizer setup for about $125 at a local place. A little expensive compared to mail order, but I needed it for the weekend and it was Wednesday already.

    Hope this helps you.

    Ken H.

    '85 K5 in process
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Not engough caster angle can cause this as well. An alignment shop should be able to check this and add the proper degree shims between the springs and axle.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  4. prjt_blzr

    prjt_blzr 1/2 ton status

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    Maybe I'll try a different alignment shop. They claim that I have 8.25* caster. I had some bolt in 3* shims made up to compensate for the extended shackles. The truck only has 4" of lift.

    I've run single and dual stabilizers and have the same problem. I'm currently running a single Warn stabilizer.
     
  5. Blazer1970

    Blazer1970 1/2 ton status

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    What is your lift like? I see that you mention extended shackles. Big arch springs plus extended shackles can allow a lot of side to side movement of the entire axle assembly. This goes into an oscillation, and you have your death wobble. What kind of spring bushings do you have? Are they a stiff polyurethane, or soft rubber? Maybe you could add a panhard bar like they use on coil spring trucks to keep the axle centered.

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     
  6. prjt_blzr

    prjt_blzr 1/2 ton status

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    I reused an old rancho lift that I had. The 4" springs have a mild arch, tapered ends and teflon inserts. I had no problems on the previous vehicle with these springs. The shackles are 1" longer than stock and use 3/8"x2" stock. All of the bushings are polyurethane.

    The odd thing about this wobble is that it is more frequent when it is cold.

    Thanks for the ideas and keep them coming.
     

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