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A First for Ackerman?

Discussion in 'The Garage' started by dhdescender, Apr 21, 2003.

  1. dhdescender

    dhdescender 1/2 ton status

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    Is ORD the first arm to take into account for Ackerman angle?

    If so...does that mean everyone running other brands, that dont apprear to account for it, (specifically avalanche) hasnt had major problems with theirs? In theory your tires will scrub around tight turns, pavement rocks etc.

    UAV has avalanche arms on it....Steve? Any problems on the road?

    Reason I ask, I made highsteer arms and forgot about the ackerman of the tierod locations. Dare I be a guinea pig?
    I guess I can still run crossover /forums/images/graemlins/smile.gif

    THX!

    -Kyle
     
  2. ntsqd

    ntsqd 1/2 ton status

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    Ackerman for which wheelbase ? If you set the Ackerman for 100% on a K5, but then someone puts one on a Sub or a truck they're going to have nice, quick, sporty car steering. If you set it for one of the longer WB's, then the K5's are going to scrub anyways.
    I'm curious to know if the part with the steering arm on it carries the same p/n from GM for all trucks, or if each is unique to the application.
     
  3. dhdescender

    dhdescender 1/2 ton status

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    I made my arms so the Tie rod attaches directly infront of the center of the kingpin, not accounting for any steering geometry at all. Basically, I didnt not make my arms with an offset hole. I cut once, and asked questions later. /forums/images/graemlins/mad.gif

    Hm. consider All chev Dana 60's are the same, but the trucks they are applied to are different. I imagine GM makes only minor modifications if any at all.

    Basically, if I drive my truck with the setup I have...Am I going to be keepin' it between the ditches? /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif
     
  4. Triaged

    Triaged 1/2 ton status

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    I didn't know ORD mada a hi-steer setup. /forums/images/graemlins/confused.gif
    I thought they just made crossover?
     
  5. JDNobodi

    JDNobodi 1/2 ton status Premium Member

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    I think Dana Trak may of been the frist to take Ackerman in account, and we all know how much Dana Trak charges for their stuff. It's good that somebody else is taking Ackerman in account.
     
  6. Anthony72K5

    Anthony72K5 Registered Member

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    Ackerman angle only matters for a truck at very slow speeds. If you are happy with how you can drive around a parking lot, there is no problem. Ackerman angles will have absolutely no noticable effect on a truck going over 45 mph.

    I repeat, Ackerman angle doesn't matter AT ALL in keeping your vehicle between the ditches. It might have some effect on your parallel parking, though.

    I'd imagine the dedicated rockcrawling vehicles have ackerman setups that are perfectly taylored to their vehicles wheelbase and slow speed purpose to allow them to turn relatively free with a locked front end, but even in that situation the difference is so negligable I can't imagine trying to worry about this on a K5.
     
  7. ntsqd

    ntsqd 1/2 ton status

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    Actually you have it exactly backwards. Ackerman effects the scrub of the inside front tire when turning. So Ackerman has little effect at slow speed and an increasing effect with increasing speed. It is most effective on a hard surface and least effective on a soft surface. Sports Car racers change their Ackerman to change how well the car 'turns in' going into a corner. The direction they change it is the same as if you put an axle or set of steering arms intended for a K5 on a longer WB like a Sub or a truck.

    Having poor or no Ackerman isn't like having little to no Castor or Camber. Lack of it won't necessarily give you the DW's, it will increase tire wear.
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    So what exactly will change Ackerman on a D60 hi-steer arm? Is it the tie-rod hole in relation to the king pin centerline? I think I understand the basic concept of Ackerman angle, I'm just unsure what needs to be done to change how much or how little Ackerman there is.

    I wanna learn dammit /forums/images/graemlins/grin.gif

    rene
     
  9. dhdescender

    dhdescender 1/2 ton status

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    Yes, its the hole in relation to the center of the kingpin.

    Ackerman angle is determined by drawing a line through the tie rod, and the center of the kingpin. The two lines (one for each side) *should* intersect at the centerline of the rear axle.

    However...consider this:

    Chevy put Dana 60's on many wheelbase vehicles (military K5's, short/long K30's), yet they never changed the ackerman angle for each vehicle. So how much does it really matter?!?!

    The problem I'm having, is i designed NO ackerman into my arms, whereas chevy would have slightly more/less for each vehicle with a stock axle.

    Everyone seems to have a different answer /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif
     
  10. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> The attachment points for the Tie Rod is what affects Ackerman, so it's only messed with if you go to high steer. For ideal ackerman the tie rod attachment hole and the centerline of the top kingpin on each side should make a line that intersects the center of the rear axle. This is difficult with front-steering high-steer arms due to tire clearance, but real easy with the behind-the-axle style. </font>
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    OK, I finally get it now...thanks!

    [ QUOTE ]
    Chevy put Dana 60's on many wheelbase vehicles (military K5's, short/long K30's), yet they never changed the ackerman angle for each vehicle. So how much does it really matter?!?!

    [/ QUOTE ]

    To the best of my knowledge the D60 was never used in a factory K5 application. 99% were installed under the regular cab with a long box, or the crew cab long box.

    Rene
     
  12. thatK30guy

    thatK30guy 1 ton status Premium Member

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    [ QUOTE ]
    OK, I finally get it now...thanks!

    [ QUOTE ]
    Chevy put Dana 60's on many wheelbase vehicles (military K5's, short/long K30's), yet they never changed the ackerman angle for each vehicle. So how much does it really matter?!?!

    [/ QUOTE ]

    To the best of my knowledge the D60 was never used in a factory K5 application. 99% were installed under the regular cab with a long box, or the crew cab long box.

    Rene



    [/ QUOTE ]

    I was just about to reply to that quote but you beat me to it. I'm wondering what exactly dhdecender was talking about here. And change your 99% quote to 100% instead. /forums/images/graemlins/thumb.gif
     
  13. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    As already said, on 4WD solid axle trucks, pretty much the only way to get the Ackerman set right would be to run the tie rod in back. If your making high steer front arms, the best you can do is set the tie rod end as wide as possible...
     
  14. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    [ QUOTE ]
    And change your 99% quote to 100% instead. /forums/images/graemlins/thumb.gif

    [/ QUOTE ]
    Hmmm, didn't they also offer on Chassis cabs in a variety of rail lengths? /forums/images/graemlins/wink.gif
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    [ QUOTE ]
    Hmmm, didn't they also offer on Chassis cabs in a variety of rail lengths?

    [/ QUOTE ]

    Yup, that's why I said 99% /forums/images/graemlins/grin.gif

    Rene
     
  16. Anthony72K5

    Anthony72K5 Registered Member

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    ntsqd I think you're wrong. A vehicle properly set up for low speed driving could tool around a parking lot with a spool in the front axle with correct ackerman angles. Ackerman angles don't matter on passenger vehicles, because the deflection they COULD take into account is dwarfed by the deflection in the tires which is something like 20 times as much as could be accounted for with "perfect" ackerman angles.
     
  17. Shaggy

    Shaggy 3/4 ton status

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    [ QUOTE ]
    ntsqd I think you're wrong. A vehicle properly set up for low speed driving could tool around a parking lot with a spool in the front axle with correct ackerman angles.

    [/ QUOTE ]

    <font color="green"> I think that you're wrong on that one, at least if you're talking about a vehicle with a spooled front axle tooling around a parking lot with the front axle engaged. When the vehicle turns the inside wheel still travels a much shorter distance than the outside wheel, the spool will cause way more problems than an incorrect ackerman angle will. </font>
     
  18. Anthony72K5

    Anthony72K5 Registered Member

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    It's all theory anway, I'm not sure if any dedicated rockcrawlers have even tried any thing like this.

    But it SHOULD work, a perfect setup with proper tire pressure and ideal circumstances SHOULD allow you to drive around with a spool without any problems (scrubing) on pavement.
     
  19. m j

    m j 1/2 ton status

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    the rockcrawlers theorize that they can turn both wheels to the limit of the steering ujoints with infinite(parrallel) ackerman.
    if it wasnt for the steering ujoint limits they would be after much greater then 100% ackerman(like many autocrossers) to get the inside tire to bite more as they do not have to worry about overheating tires like a long roadcourse car would.

    100% ackerman is not perfect ackerman
    different applications work better at different settings
     
  20. Shaggy

    Shaggy 3/4 ton status

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    [ QUOTE ]
    It's all theory anway, I'm not sure if any dedicated rockcrawlers have even tried any thing like this.

    But it SHOULD work, a perfect setup with proper tire pressure and ideal circumstances SHOULD allow you to drive around with a spool without any problems (scrubing) on pavement.

    [/ QUOTE ]

    <font color="green"> Uh, no, it won't. There isn't even a debate about this, a spool makes both wheels turn at the same speed, all the time. If you turn then the inside tire will travel a shorter distance, and there will be tire scrubbing since there is no differential to compensate for the different tire speeds. Not even a perfect Ackerman angle is going to prevent this from happening. In order to prevent it you would have to somehow change the laws of geometry.

    You could have no Ackerman built into your steeirng and you would likely notice little difference between that and a steering system with perfect ackerman angle if you were trying to drive in circles with a spool. </font>
     

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