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Crossover steering info!!!!!!!!!!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by mudddog91, Jul 22, 2001.

  1. mudddog91

    mudddog91 1/2 ton status

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    Hey for future reference any of you out there decide to fabricate your own crossover steering setup keep in mind the length of your pitman arm to steering arm.if one is longer or shorter than the other you steering will not work exactly right!!!!!!!Just something ive learned and thought Id pass it on!!!!!!!!
     
  2. michaelm

    michaelm 1/2 ton status

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    so what ratio is correct?
    equal?
    i was thinking pitman arm slightly longer than steering arm would help on twisted up moments to allow more steering.
     
  3. FWP

    FWP CRS

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    I'm not following you here. Can you explain further?

    <a target="_blank" href=http://fwp4x4.rockcrawler.com>fwp4x4.rockcrawler.com</a>
     
  4. Triaged

    Triaged 1/2 ton status

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    You would want to make it as long as the one from the factory. If you make it shorter it would make the steering faster and have too much travel. If you made it longer it would make the steering slower and not have full travel.

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
     
  5. AZK5

    AZK5 1/2 ton status

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    Changing the length of the pitman arm has no effect on how far the axle will turn. A short steering arm will require more force to turn the wheels. A longer steering arm will require less force to turn the steering arm. For best steering geometry the crossover drag link should be parallel to the axle. The forged pitman arm is a set length don't assume that a purchased steering arm will be the right length. I put my dropped pitman arm on, put the drag link I made on the pitman arm and then measured the length that the steering arm needed to be to keep my drag link parallel. Then I fabricated my steering arm to that length. My steering arm is longer then the factory steering arm so my K5 steers easier then before. The crossover drag link has no effect on flat ground steering. It allows the truck to steer when twisted up and helps to eliminate bump steer.
    CB

    1973 K5, 400TPI,TH350, 203/205, Dana60/Detroit/5.38 front and rear, 4" lift, 38" TSL's on steel wheels
     
  6. MaxCrack

    MaxCrack 1/2 ton status

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    Is there a limit on how far the steering box will turn, or is it limited by the axle turning radius?


    That's because I'm the devil.
     
  7. ChadH82

    ChadH82 1/2 ton status

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    So does everything on the off-road.com write up work or did I just blow some cash
    <a target="_blank" href=http://www.off-road.com/chevy/tech/d60crossover/>http://www.off-road.com/chevy/tech/d60crossover/</a>

    Chad
     
  8. Triaged

    Triaged 1/2 ton status

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    The box will turn 90deg. Just don't make the arm too long so that the box runs out of travel.

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
     
  9. michaelm

    michaelm 1/2 ton status

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    <blockquote><font class="small">In reply to:</font><hr>

    the length of the pitman arm has no effect on how far the axle will turn

    <hr></blockquote>
    put that into extreme terms and your statement makes no sense. if you dramatically increase the length of the pitman arm and the steering arm remains the same length you quicken the steering. of course the relative lengths of the steering vs pitman arms effect the amount of steering vs input. as well as having more travel left in the box for when the axle is at odd angles may help to get a few more degrees of steering input to the steering arm, just an untested theory.

    <blockquote><font class="small">In reply to:</font><hr>

    For best steering geometry the crossover drag link should be parallel to the axle

    <hr></blockquote>

    kind of a case of choosing which direction you want your bumpsteer to go at street sized bumps. with the short factory style steering i put the draglink in a slight slope down from pitman to steering in the hope that as the spring got longer on compression the drag link also lengthened. you will get some bumpsteer on any linkage that travels from the frame to a leaf sprung axle.

    what is the length of both pitman and your steering arms? is there a ratio of lengths that is considered good?
     
  10. AZK5

    AZK5 1/2 ton status

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    In extreme terms you are right. But with available pitman arms you can go from bumpstop to bumpstop on the axle. In which case it won't matter how long the pitman arm is.
    When I said parallel, I meant front to back, the steering arm and pitman arm length don't have much effect on the angle of the drag link from top to bottom. My drag link is parallel to my axle from front to back and angles a few degrees up from steering arm to pitman arm. It would be ideal to make the drag link parallel from top to bottom also but difficult with any kind of lift. I have 2" lift springs on my K5 so the crossover drag link doesn't have much angle to it.
    I don't know what my ratio is, but the steering arm I have now is longer then the factory so it steers easier.
    CB

    1973 K5, 400TPI,TH350, 203/205, Dana60/Detroit/5.38 front and rear, 4" lift, 38" TSL's on steel wheels
     
  11. mudddog91

    mudddog91 1/2 ton status

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    Ok this is what ive found.First of all I work for an a/c overhaul facility and ive got good buddies in engineering and machine shops,so I built my own steering arm,the one on the knuckle,and I made it to be 7.5 " from balljoint to drag link attach,I used a jeep pitman arm which was 5.5" from the box to the drag link attach and my steering would not go full travel.
    SO i had an engineer put my system on the auto cad and found that the steering arm needs to be exactly the same or a little shorter than the pitman arm.If you think of the arms as gears( since they move in an arc or circle) then you can understand why the smaller arm will move more than the bigger arm so YES the length is definitly critical.I just thought Id share with those out there that are into building things and wanting to build them correctly and understand why&gt;&gt;&gt;&gt;&gt;
    And yes you are correct when you say " with te available pitman arms out there you can go from stop to stop" but only if your steering arm is the correct length and this is waht i was trying to relate wiht those who didnt know!!!!!!!!!!!!!
     
  12. mudddog91

    mudddog91 1/2 ton status

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    the steering box has internal stops. and if you hit these before you hit the axle stops then you put side loads on the box causing it to leak fuid past the seal around the sector shaft!!!!!
     
  13. FWP

    FWP CRS

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    The lightbulb in my head just came on[​IMG][​IMG], now I get it. Good posts with good info, thanks guys.

    <a target="_blank" href=http://fwp4x4.rockcrawler.com>fwp4x4.rockcrawler.com</a>
     

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