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if going hydraulic assist, why do crossover also?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by four_by_ken, Dec 17, 2001.

  1. four_by_ken

    four_by_ken 1/2 ton status

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    I am going to go for hydraulic assist, but I have been thinking...
    With assist, all the mechanical link is for, is just a backup if you loose hydralics for whatever reason. So, I am thinking of saving myself some time and money and not doing the cross over, just stick with the normal steeing and complete the assist?
    Opinions?

    Thanks
    Ken H.

    '86 K5 up and coming
    14 bolt(Detroited),10 bolt
    44 TSLs
    468 BBC, 350 trans, 205 transfer
    Rust free in Michigan!
     
  2. CK5

    CK5 In my underwear Administrator Premium Member GMOTM Winner Author

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    Maybe this will help:

    Steering problems are very common on a lifted 4x4, and unfortunately for us, the GM straight axle steering is the worst of them all for problems associated with a lift. The general term: ?steering problems? basically amounts to one of 4 specific problems.

    1: It breaks. Crossover (or any other kind of steering) doesn?t do much if you?re steering box isn?t attached to the frame, or if the linkage is broken. But the parts in the kit are beefy enough it should never break. A box brace is always a good idea also.

    2: It lacks power. Crossover doesn?t do much for actual steering power, you?ll have to go to hydraulic assist or other steering upgrades for that one. It may help just having the proper geometry from the crossover, but that?s not the main purpose of crossover.

    3: This is the good stuff: Bumpsteer, Bumpsteer is defined as unintentional steering motion of the front tires when the suspension moves in a straight up and down motion, for example hitting a speed bump or large dip in the highway. This causes both front tires to move upward the same amount. You can feel bumpsteer in your truck by letting go of the steering wheel when you?re driving over speed bumps or "whoops" in the highway. If the wheel jerks as you go over the bumps, you have some degree of bumpsteer. Stock GM steering can work well in preventing bumpsteer just because the steering linkage is pretty well located for vertical travel and moves in the correct arc to keep the steering wheel and the tires in sync.
    Crossover steering will have some bumpsteer because the leaf spring suspension moves straight up and down while the crossover draglink moves side to side. Since the draglink end at the axle will move in an arc, it will have some small component of side to side motion as it travels vertically and this side to side motion causes bumpsteer. However, this is generally an acceptable level of bumpsteer for most drivers.

    4: This is the really good stuff: Roll steer. Roll steer is defined as unintentional steering motion of the front tires when front axle "articulates" compared to the frame, meaning one side moves up while the other goes down. Roll steer conditions are possible in two driving circumstances: cornering, where the whole body rolls compared to the frame, and off-road driving where only the front axle moves compared the frame. Roll steer is usually just annoying when driving on the street, it?s hard to get enough body roll to cause serious problems.

    The off-road articulation situation is the one that concerns us. The steering action pops up in 2 ways; One is when the axle housing itself under steers when articulated due to the arch in the spring. This motion is one we just have to live with because it's due to the motion of a leaf spring suspension itself. As one side of the suspension compresses and the other extends, the leaf will make the axle move forward on the extension side, and backward on the compression side. This motion will steer the axle housing under the vehicle. Make sure you understand how this works before you continue reading, it's important to understand that the axle housing steers under the truck when it articulates.

    The other way the axle can steer is when the steering linkage moves in a different arc than the axle. This is found in poorly designed link type suspensions, and is also found in the factory GM front suspension. This is where crossover steering comes in to play. Imagine the standard GM steering on your truck, with the suspension twisted in such a way that the left (driver?s side) tire is drooping away and the right side is compressed. The left side of the front axle will be moved forward because of the increased arch in it?s spring, and the axle will be at an angle under the truck because right side is moved back due to the spring being close to flat on that side. Now try to turn left. Your steering box turns the pitman arm so that the end of the arm moves to the front of the truck. But the end of the draglink where it ties to the axle is already closer to the front of the truck than it?s supposed to be so your pitman arm?s motion doesn?t actually turn the tires to the left, it just makes them straight again.

    Keep turning the box till you?re against the stop and you?ll find that you can only get the tires to point straight, it won?t move them to left because the steering box is maxed out and doesn?t have any rotation left to pull the draglink forward.

    Now imagine the same scenario with crossover steering. Since the draglink in a crossover setup moves side to side, the angle of the axle under the truck doesn?t make an appreciable difference in how the linkage acts when you steer. A little forward and backward motion of the axle ends doesn?t matter so when you move the steering wheel, it translates into side to side motion of the draglink and steers the wheels all the way to the axle stops. This is the big deal with crossover steering, it works when you twist the truck up in an off-road situation.

    Steve

    Director of Global Expansion
     
  3. four_by_ken

    four_by_ken 1/2 ton status

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    Thanks... but... I always knew what happened, but did not know exactly why... but I still have the same question...

    With the hydraulic setup, when you turn the wheel, the ram will extend or comppress also, no matter what the draglink is doing, right:? So, the wheels will turn also. So, why not just leave the stock steering (with raise arm, block, etc) for when hydraulic is not there. Not trail riding, but just for geting towed back or something like that. Then allow the hydraulic to do its job.

    Am I thinking about this wrong?

    Ken H.


    '86 K5 up and coming
    14 bolt(Detroited),10 bolt
    44 TSLs
    468 BBC, 350 trans, 205 transfer
    Rust free in Michigan!
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    As Steve said, when articulated you quickly run out of "turn" due to steering geometry. Once the box has gone as far as it can, a hydro ram that forced it to turn further is going to break something. This is true with all aspects of Hydro assist regardless of steering geometry. You have to make sure that the ram travel NEVER exceeds the steering limits, including the steering box.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  5. CK5

    CK5 In my underwear Administrator Premium Member GMOTM Winner Author

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    If your not going to flex it out (where x-over really helps) at all and it is more of a mud truck or light trail truck you prolly don't need the cross-over, I would think you would be fine with just the hydro assist, maybe Matt (TheLakeRat) can chime in and give some more insight.

    Steve

    Director of Global Expansion
     
  6. Boss

    Boss 1/2 ton status Author

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    Wrong. Hydro "assist" Assists the steering, not steers. The ram is controled by the draglink pushing and pulling. (which is controled by the gearbox to the pitman arm.) If I took off my draglink and then turned the wheel, the ram would do nothing but sit there. All the ram does is "Assist" the steering. It pushes and pull at the command of the draglink. Hope that helps. You can do the hyrdo assit without the crossover, but you won't experience steering to the fullest.[​IMG]
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  7. four_by_ken

    four_by_ken 1/2 ton status

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    Well, it is definately a mud truck, but by far anything mild. DEEP mud and trails from two tracks to real nasty stuff.

    Probably just end up doing it right and just do the cross over. I hate taking short cuts, so looks like back to cross over.

    Just think $185 or what ever for a steering arm is a complete rip off. I'll get one made instead. Just was looking for a way to not have to tear the axle apart to get the knuckle drilled.

    Oh well.

    Ken H.


    '86 K5 up and coming
    14 bolt(Detroited),10 bolt
    44 TSLs
    468 BBC, 350 trans, 205 transfer
    Rust free in Michigan!
     
  8. four_by_ken

    four_by_ken 1/2 ton status

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    Making more sense now. Cross over will be done.

    But, the drag link controls the ram... I dont think it does. The ram is controlled by the steering box. I dont think the ram is connected to the drag link in anyway. Am I right. The drag link and the ram are controlled by the same thing, the box.. right?

    Ken H.


    '86 K5 up and coming
    14 bolt(Detroited),10 bolt
    44 TSLs
    468 BBC, 350 trans, 205 transfer
    Rust free in Michigan!
     
  9. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    The ram is powered using pressure in the steering box which results from pushing on the drag link. No drag link, no pressure.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  10. Boss

    Boss 1/2 ton status Author

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    Exactly what Baddog said. The fluid comes from the gear box, but it's the drag links that pushes and pulls to get the ram to operate.

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  11. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Ken-

    Call up RockStomper and ask about their crossover kit. I got the kit with steering and pitman arms, 4 new tierod ends, the tierod, and the draglink... all for $475.

    I think that RockStomper was only asking $150 for the draglink, if that is all you needed. [​IMG]

    What are you expecting to pay for the conversion, aside from the crossover costs?

    <font color=red>GOT MUD???</font color=red>
    My license plate reads:<font color=blue> 8 YR SUV</font color=blue>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s - 36" TSLs
     
  12. four_by_ken

    four_by_ken 1/2 ton status

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    I can either make, or get made the whole shot. Just comes down to what I want to pay and what my time is worth in makeing the stuff and waiting for my buddies to make some of it.





    Ken H.

    '86 K5 up and coming
    14 bolt(Detroited),10 bolt
    44 TSLs
    468 BBC, 350 trans, 205 transfer
    Rust free in Michigan!
     

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