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Ever hear of a road force test?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jimmyjack, Aug 10, 2001.

  1. jimmyjack

    jimmyjack 1/2 ton status

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    As some of you know I've been chasing a vibration that goes away then returns after a quick fix. I replaced a u joint (almost had a driveshaft built for $250), it got better, I lowered the t case, it got better. I rebalanced the rear tires, it got better but ALWAYS comes back. Today I went to get my tires rotated and rebalanced. Sales guy tells me they did a road force test that simulates the weight of the vehicle on a tire being balanced. One was rolling at 90 lbs. Average is about 30. They replaced the one and it "tested" at 11 lbs. The other 3 were around 25. Anyway I think I found my problem. Some of you vibration sufferers might want to look into it!.

    "My blazer may be slow, but it goes faster at higher speeds"
    <a target="_blank" href=http://community.webshots.com/user/blazerk5>http://community.webshots.com/user/blazerk5</a>
    Jim
     
  2. solowookie

    solowookie 1/2 ton status

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    hey, you got any more details, like how to actually perform the tests, what they do to fix it etc.???

    <font color=blue> Jeff - may the force be with you</font color=blue>
     
  3. BlueBlazer

    BlueBlazer 1/2 ton status

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    OK guys, this happens to be my area of expertse. Were I work we have a Hunter balancing machine that tests the road force. Basically, there is a large roller that is applied with a certain amount of pressure to the tire that is rolling on the balancer. This roller checks the runout and out of round of the tire and gives you a road force reading. From this you can tell if the tire will vibrate on the road. Now heres whats really cool. You can use a rim runout device on the balancer which tells the computer any imperfections in the rim (which there always is). You then make a mark on the tire and one on the rim, spin the tire to line up the marks, and air it back up and retest. This usually will bring the tire within tolerances unless its worn choppy or has a badly bent rim. When I put my 35" Mud Kings I used this machine to balance them. Two of the tires were showing a good possibility of having a vibration. I match mounted them and now all four ride like a cadillac. Another thing possible with this machine is using patch weights. The computer will tell you where to put the patch and how much it must weigh. Then apply the patch and respin it. If it still needs weight it is usually a very small clip on weight that it needs. But yes, 90 lbs is very bad. In fact I can guarantee its what caused your vibration. On our machine, 40 lbs is the limit and anything over that will usually cause a vibration. Any more questions, feel free to ask.

    82 K5, 6.2L Diesel, sm465, np205, 14 bolt welded, 8 lug 10 bolt lock right, 410 gears, 35" Mud Kings
    SPEAK SOFTLY AND DRIVE A BIG TRUCK
     
  4. txbartman

    txbartman 1/2 ton status

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    great info. thanks

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
    PM me for a great deal on blinker fluid! Best price on the net!
     
  5. solowookie

    solowookie 1/2 ton status

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    hey, thanks for the explanation! that was fantastic! [​IMG]

    <font color=blue> Jeff - may the force be with you</font color=blue>
     
  6. Burt4x4

    Burt4x4 3/4 ton status

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    Groovy makes me want to drive out to IL and have you balence my new SSRs (when I get them)...[​IMG]

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
    <a target="_blank" href=http://www.geocities.com/baja/5099>www.geocities.com/baja/5099</a>
     
  7. 502Burban

    502Burban 1/2 ton status

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    If BlueBlazer62 is talking about the Hunter GSP9700, like I think he is, Hunter's web site has a nice feature that will let you search for a tire shop that has one of these very cool machines. Here's the link so you can find one near you: <a target="_blank" href=http://www.gsp9700.com/pub/search/FindGSP9700.cfm>www.gsp9700.com/pub/search/FindGSP9700.cfm</a>.

    Robb
    '73 GMC Suburban - 502DFI
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  8. jimmyjack

    jimmyjack 1/2 ton status

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    The guy at discount tire told me its about $20 a pop

    "My blazer may be slow, but it goes faster at higher speeds"
    <a target="_blank" href=http://community.webshots.com/user/blazerk5>http://community.webshots.com/user/blazerk5</a>
    Jim
     
  9. BlueBlazer

    BlueBlazer 1/2 ton status

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    Oh yeah, its 40 bucks to do this to four tires at my shop. This also includes lifetime rebalance and rotation. So for 10 bucks a tire its a good deal. And yes it is the hunter GSP9700 we have. Weve had it for just over 2 years now and it still works great.

    82 K5, 6.2L Diesel, sm465, np205, 14 bolt welded, 8 lug 10 bolt lock right, 410 gears, 35" Mud Kings
    SPEAK SOFTLY AND DRIVE A BIG TRUCK
     
  10. Blazer79

    Blazer79 1/2 ton status

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    Burt, you can send me your SSRs and wheels when you get them and I'll have them set perfectly for you, then I'll test them carefully in all kinds of terrains to make sure they are perfect. All this for free!! [​IMG]

    <font color=purple>//////
    <a target="_blank" href=http://blazer79.freeyellow.com>blazer79.freeyellow.com</a></font color=purple><font color=black>
    Soon a 454 K5!!</font color=black>
    [​IMG]
     

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