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drop pitman vs drop steering

Discussion in 'The Garage' started by Pookster, Jul 4, 2003.

  1. Pookster

    Pookster 1/2 ton status

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    Which is better? I have a drop steering, but I get terrible "bump steer" where the steering wheel turns when I hit a bump. This is quite terrible for towing, and a little dangerous! is the drop pitman any better than using the drop steering?
     
  2. HarryH3

    HarryH3 1 ton status Author

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    Try disconnecting your front sway bar and see if the bump steer goes away. If it is on a steep angle due to your lift, then it will fight with the drag link for control of the front axle as the suspension cycles. /forums/images/graemlins/shocked.gif The ORD sway bar disconnect kit will let you still run your sway bar, while letting the ends at the axle move. /forums/images/graemlins/cool.gif

    As to whether to use a raised steering arm or a dropped pitman arm, I prefer the raised steering arm. A dropped pitman arm provides a longer lever for the rest of the suspension to apply pressure against your steering box. That just makes it more likely that you'll crack the frame around the steering box. /forums/images/graemlins/frown.gif (When you get into 6"+ lifts, then you don't have much choice, other than cross over steering, as you'll need the steering arm and the dropped pitman arm).
     
  3. Pookster

    Pookster 1/2 ton status

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    I already have the ORD disconnects, and the ORD frame brace.

    There is no "frame play". Im suffering from the classic, "bump steer". THis is the way I've figured out whether it is your brake caliper siezing or your suffering from bump steer:

    Find empty parking lot of some sort.
    Get some speed, (20-25mph, or higher if you have the room).
    Let go of the steering wheel, and jam on the brakes hard.

    If the truck moves to one side, you may be suffering from bump steer, but you probably have a sticky caliper or brake issues.

    If the truck stays in the same line as it was before, but you see the steering wheel move (mine moves left) and then after you stop, it returns back to the original spot, you most definately have bump steer.

    I have The raised steering arm, and the drag link is parallel with the body at the moment.

    So I've been researching some of the posts here, it seems like some people say its a bad steering stabilizer, others say steering stablizers have nothing to do with it( which I would have to agree, steering stablizers cant help with articulation induced steering issues, at least from what I know).

    And your saying the drop pitman causes more stress on the frame? Certainly not what I wanted to hear. /forums/images/graemlins/eek.gif

    So then on some of the other posts, people talk about using a Z or S shaped drag link. Some say it helps, others say its useless, or somehow doesnt really help all that much. /forums/images/graemlins/confused.gif

    I can only see 3 solutions to my problem:

    - Drag link change (either to that AutoZone: ES2234R or the more costly superlift one)
    -Steering stabilizer (relatively cheap, and I know its been at least 4 years since I changed it)
    - Dropped Pitman
    - Maybe a caster issue, but not certain. /forums/images/graemlins/1zhelp.gif

    I wanna hear ideas! Thoughts! something!
     
  4. m j

    m j 1/2 ton status

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    draw a sketch with the drag link as the radius of an arc
    as the springs compress the axle will move rearward making the distance from the steering box to the steering arm greater.
    if the drag link is level at rest it will steer the vehicle as the axle is now further away and the draglink arc is getting shorter.
    you cannot remove this, you can play with angles to reduce how much you feel.
    lift springs? the drag link should slope down from the steering box to the axle.
    why? as the suspension compresses and move the axle rearward the arc the draglink is moving will also follow MORE closely.
    out of time here but if you chew on that for awhile you will see what I am trying to explain.
     
  5. Pookster

    Pookster 1/2 ton status

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    but then, wouldnt the Z shaped drag link eliminate /reduce that sensation? Also, how am i supposed to play with the angle of the drag link? SEems like there is no way to adjust such a thing.
     
  6. m j

    m j 1/2 ton status

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    the shape of the drag link does nothing, you could shape it like a pretzel and have not bearing on the arc the tierod ends travel.
    that is smoke and mirrors marketing you must ignore.
    the angle formed between the tierod pivot at each end is all that you look at.

    the Z draglink is for getting the tierod ends in the centre of their movement to avoid bottoming them.
    that is their only function.

    well if you are lucky enough to still have some of the stock stuff kicking around you could put a stock steering arm on and test it for bumpsteer.
    or if you have a spacer under the steer arm you could remove that to induce some angle.
    or if you have a stock pitman and 4" lift steer arm you could go the other way, a 2" drop pitman and stock steer.

    if you are a faber you could try moving the steer box as far forward on the frams as possible to get a long draglink.

    the sheer volume of posts on this topic will overwhelm a search /forums/images/graemlins/smile.gif
    most of them are full of misinfo as well, like searching Pirates for link suspensions

    I would take stock of what you have on hand or can get used cheaply then try a few things, keeping in mind the $ for crossover conversion.
    crossover will still bumpsteer(as will any leaf sprung once you are tuned into what Bumpsteer is, remeber when you didnt notice it, ignorance can be bliss) but i think it will be less then a bad stock style.
    you may get pretty close juggleing(speeling?) cheap stuff, at least to the point where a small road imperfection is unnoticable

    again start with drawing it out until you see what is going on then you will know where you want to be.
    hard part is figuring how the axle moves
     
  7. m j

    m j 1/2 ton status

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    [ QUOTE ]
    A dropped pitman arm provides a longer lever

    [/ QUOTE ]

    not that much longer lever,should be same radial distance no, but granted a little further from the bearings
     
  8. Pookster

    Pookster 1/2 ton status

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    Yeah, I've been runing through my head all the little angles and what not, and it seems rather IMPOSSIBLE to get rid of bump steer. Thinking of how the factory style did it, the negatively arched spring of course, shortened the distance between the axle and the steering box when the suspension was compressed. (and we all know the 2" of compression the factory gave us). Using lift springs, when it compesses, it actually moves the axle away from the steering box.

    It would seem like no matter what angle the pitman arm, steering arm, or drag link is at, the fact is, to keep the wheels straight, the drag link needs to be shortened and extended. This is probably nothing new to most of you, but I guess it just took a while for it to dawn on me.

    im playing around with some ideas in my head, it might just work. A little weird, but... heh...
     
  9. HarryH3

    HarryH3 1 ton status Author

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    [ QUOTE ]
    [ QUOTE ]
    A dropped pitman arm provides a longer lever

    [/ QUOTE ]

    not that much longer lever,should be same radial distance no, but granted a little further from the bearings

    [/ QUOTE ]

    Actually it increases the leverage by 50% /forums/images/graemlins/eek.gif The distance between the bottom bolt on the steering box and the bottom of the stock pitman arm is 4 inches. Adding a 2-inch drop in the pitman arm will increase the distance to 6 inches. Probably not a serious issue if you have beefed that area of the frame, but it's likely in increase the chances of a stock frame cracking. /forums/images/graemlins/frown.gif
     
  10. Pookster

    Pookster 1/2 ton status

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    Your right on that one.. certainly more leverage on the frame.
     
  11. Pookster

    Pookster 1/2 ton status

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    Just noticed something else...

    Once you forgo the sway bar, or add the ORD disconnection kit, I believe you increase bump steer. The reason being is that your taking something that had had two fixed points of control, and basically taking it away. The sway bar was guiding the overall position the axle was able to move up and down. It probably even forced the spring to bend at a certain point, rather than the natural compression point of the spring (hence controlling some of the bump steer). The ORD unit gives it 3 points instead of two, thereby letting the axle have more horozontal movement.
     
  12. m j

    m j 1/2 ton status

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    ok, i thought you were refering to steering box damage not frame
     
  13. m j

    m j 1/2 ton status

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    so the aim is to get the draglink to be going through an arc that increases its length for a few inches of compression,
    after it hits parrallel it will start bumpsteering left on you.
    agreed you cannot eliminate bumpsteer unless you go full hydro steering, even then you will have the wheelbase varying on articulation steering the vehicle.
    you can move things to reduce how much is felt for a few inches of travel.
    sounds like you are on the path now /forums/images/graemlins/smile.gif

    edit* and yes the disconnects do allow more axle motion removing the massive bind of the swaybar
     

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