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Shakes when I hit a bump

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by TopOff, Jan 16, 2002.

  1. TopOff

    TopOff 1/2 ton status

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    I just recently, re-found this board. I can't believe how extensiive it is. I anticipate many more posts (hopefully more replies than ?).

    Anyway, When I hit little bumps/potholes/railroad tracks in the road w/ the front drivers side tire, the whole front end shakes almost violently. I found if I tighten down the front shackles, this goes away a little bit. I replaced the RC9000s with EZ ride shocks. Better ride, but the shakes are still there.

    I checked all suspension, looks OK. I checked steering rack, looks good, no cracks still. What else?

    I have steel wheels, no cracks along the rims.

    Has anyone come across this?

    This is a '73 Blazer 383/350/203 with 4" EZ ride and EZ ride shocks. 35" BFG ATs 3/4 ton with ARBs F&R.
     
  2. How are your tires, mine did that same thing, turns out my tires were worn out too bad, they would just not make it out of the bump, just kept shakin, stopped after a couple of seconds though.

    '84 K5

    Chevy in my blood.
     
  3. TorkDSR

    TorkDSR 1/2 ton status

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    check your buody mounts, then tork em down. then kick your front bumper and see if that is the shaker, then tork it down

    beligerence doesn't justify intelligence.
    <font color=blue>wheelers hate posers.</font color=blue>
    <font color=red>79k15/400/700r4/205/38.5</font color=red>
     
  4. TopOff

    TopOff 1/2 ton status

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    My tires are half way good (gone).

    It DEFINATELY is NOT the bumper. Maybe body mounts. I will check tonight.

    The WHOLE truck shakes from side to side when I hit a bump. This only happens going about 20 - 30 mph. Any faster... no problems. If I hit the brakes, the shaking slows down real fast then stops, even though I am still moving.

    If I grab my front bumper and shake the truck from side to side, I noticed the shackles were wiggling. So I tightene them down and it worked for a day. Then it came back.

    BTW: Previously, I found my front drivers suspension U-bolts REALLY loose. I have since, torqued those down and checked all other U-bolts. The rest were tight.

    Thanks for the replies.... keep e'em coming :)

    '73 Blazer, 383 Howell TBI, 3/4 ton ARB F&R (3.73), 35" BFG AT&MT. TH350/203 looking for a SM465 conversion
     
  5. Greg72

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

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    If it was me, I would assume that every body mount and bushing was frozen, decayed, or dry-rotted.

    You're in a similar situation to myself (Mine's a 72) As I've been going through and upgrading the bushings &amp; shackles, I was amazed at what 30 years of wear-and-tear can do to these trucks.

    If you haven't done bushings yet, that's a good start. I'd also check balljoints, and the draglink ends. Steering dampers can "mask" a lot of problems in the front end so they're harder to diagnose.

    Finally, it may just be "bump-steer" which happens on lifted trucks. If everything else checks out OK, then you're only solution is to switch to a "crossover steering" setup. It will solve the problem, but it is pretty expensive. Check the Technical section for the writeup, or search the message board archives....you should see it discussed a LOT.

    Welcome to the board...! Put a few more bits of info in your profile (Year of truck, mods, etc)....that will help people give you more accurate answers! [​IMG]



    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  6. TopOff

    TopOff 1/2 ton status

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    Sorry, about the limited information. I tried to clear that up in my signature file.

    The body posts are OEM. :D
    I am thinking about a 1 or 2" body lift. But I am afraid of the poly bushings. Are these really that much noisier than the rubber ones?

    The axles are fairly stock out of a 90 suburban.

    I forgot also to say, that I have checked the ball joints. They check out OK. No wobbling with the wheel off the ground and trying to shake it up and down. Tie-rods look good.

    The only thing that looks out of place is one of the middle pack of springs is not quite with the rest of the spring pack. It is kinda' twisted. I didn't think this could be the cause though.

    Also, all suspension bushings (poly) are 1-2 years old. So I don't think this could be it either.

    '73 Blazer, 383 Howell TBI, 3/4 ton ARB F&amp;R (3.73), 35" BFG AT&amp;MT. TH350/203 looking for a SM465 conversion&lt;P ID="edit"&gt;&lt;FONT class="small"&gt;&lt;EM&gt;Edited by TopOff on 01/16/02 04:23 PM.&lt;/EM&gt;&lt;/FONT&gt;&lt;/P&gt;<P ID="edit"><FONT class="small">Edited by TopOff on 01/16/02 04:25 PM.</FONT></P>
     
  7. TopOff

    TopOff 1/2 ton status

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    Anyone else?

    '73 Blazer, 383 Howell TBI, 4" EZ-ride (spring only), 3/4 ton (90 sub') ARB F&R (3.73), 35" BFG AT&MT. TH350/203 hoping for a SM465 conversion
     
  8. BIGJ

    BIGJ 1/2 ton status Author

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    Most likely the "shimmy" or "death wobble" as others have called it is due to some kind of alignment/balljoint/tie-rod end problem in the frontend and/or out of round tires. After swapping axles from a 10 bolt to a dana 60 I started experiencing the EXACT same symptoms you described earlier having never personally had a vehicle that had the "death wobble". I could be driving on almost flat pavement and it would start if I hit the smallest bump at low speed. Everything (bearings, joints, rod ends, etc...) in the D60 were new so I automatically ruled out that stuff. After an alignment the "shimmy" was still there but barely. I switched out my swampers for a set of loaner street tires to see if it was the TSL's, and it went away completely. My bud had this same problem in his Burb. He switched his swampers for some BFG's and it cured the "death wobble".

    I would check the tie-rod ends, draglink, wheel bearings, ball-joints, and anything else that could be worn out on the front end. Have an alignment done too if it's been a long time. The shimmy will wear out all that stuff and then start to loosen u-bolts and body bushings, etc.... And, if your tires arent close to round, they will contribute also, heck they could even be the source of the problem.

    BIGJ
     

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