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Automotive Indy Car IRS Single Spring

  1. Jan 15, 2012 #1
    where do i locate the spring between the upright and
    the main space frame?
    this is '63 era technology build. first rear engine American mades
    like Mickey Thompson cars.
    can't quite get a good look at rear suspension in most of pic's.
    in the front i can go right down the middle but
    in rear the drive axles are in the way.

    Have A Nice Day!

    Attached Files:

  2. jcsd
  3. Jan 15, 2012 #2
    If you look closely you'll see the coilover mounted on the inner upper suspension pivot and the lower pivot on the upright. The farther out on the bottom of the upright, the more direct motion ratio you get. However, the more angle away from perpendicular the less motion ratio you get.

    Front should be very similar but inside the arms.
  4. Jan 15, 2012 #3
    i'll have to back pedal here.
    i would like to take advantage of progress.
    http://www.aaim1.com/pdfs/anatomy.pdf [Broken]
    it will be double wishbone like this current car.
    a arms will be mounted to frame square not like this diagram.
    how do i apply single spring to this?

    Have A Nice Day!
    Last edited by a moderator: May 5, 2017
  5. Jan 16, 2012 #4
    You want to do a mono-shock design? Do you mean a sliding shuttle design as was used on some cars in the 90s? In general, unless you are racing a FV you probably don't want to do a mono spring setup.
    Perhaps some more information is needed here.
  6. Jan 16, 2012 #5

    Ranger Mike

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    the evelution of Indy suspensions stems from the requirement to narrow up the " car body" and lighten the weight as much as possible to the point where we spring / shock is now mounted inboard and runs through the bell crank via push rod. The major draw back to this design FOR THE STREET is the fact that this suspension is VERY twitchy.

    These setups run very high spring rates, have very limited travel and are damn near like a go cart set up as they are sprung so tight. These set ups pound the heck out of the suspension parts and are very hard on t he rod ends.
    I would even say this design is flat out dangerous for the street. You have no room for error and the set up it totally no forgiving. When you have the earlier double wishbone set up with the shocks mounted inboard to the top wish bone and the bottom to the frame,it is a lot more forgiving. And a lot softer on the ride. I can not over stress the input form my drivers ( 30 plus years of seat time and many road course championships) the push rod set up is flat out no forgiving regarding drive input. No room for mistakes.
    Last edited: Jan 16, 2012
  7. Jan 16, 2012 #6
    I see no reason why pushrods and bell cranks can't work just fine for the street. A number of road cars use the setup. It's not common because it's expensive and the aero benefits are rather limited in a car with fenders. It also doesn't always package that well.
  8. Jan 16, 2012 #7
    the mechanical engineering part is done.
    the spring goes from bottom of upright to
    top of frame at roughly 45 degree angle.
    i was just concerned with loading upright unevenly.
    i guess if it's rigid enough that's a non-issue.
    i think building it to carry load of double a arms and
    axle carriers will as a side benefit make it strong
    enough for spring mount.
    in plain language i'm not going to beef it up anymore than that
    for spring.

    Have A Nice Day!
  9. Jan 16, 2012 #8
    One way to do it:
    http://www.cardomain.com/ride/3360047/1976-mclaren-f1/page-4 [Broken]

    If the suspension/upright can't handle the asymmetrical loading it's not strong enough to handle the braking load.
    Last edited by a moderator: May 5, 2017
  10. Jan 17, 2012 #9
    ranger mike & mender
    mike didn't see your last post until now.
    no street here. no bellcrank inboard springs.
    we're good for now.

    Have A Nice Day!
  11. Jan 17, 2012 #10
    It appears the question was answered but as a general tip, the guys on the Apexspeed forum can be very good when it comes to these sort of questions. Apexspeed is a forum specifically talking about open wheel, amateur formula cars. There are several members there who have built their own cars. Additionally some of the manufactures such as Stohr and several of the F1000 designers post and answer questions.

    (No, I don't have any financial ties to Apexspeed and I didn't join the forum to spam it. With that out of the way, I am Higerian Roialty. Send me banke numbrs I send you sister princes OK?)

    Here are a few threads with a few good pictures
    http://seanmaisey.blogspot.com/sear...-max=2012-01-01T00:00:00-05:00&max-results=50 - lots of pictures as he restores a car.
    http://www.apexspeed.com/forums/showthread.php?t=25227 - a fair number of pictures but many were removed a few years after the fact (?)
  12. Jan 17, 2012 #11
    the whole idea is to build something that
    most people can build in their garage.
    this car uses mild steel and is arc welded together.
    1" square .063 wall tubing.
    in place of bends the tubing is cut at 45 degree angles.
    a Popular Mechanics type project.
    more building per dollar.

    Have A Nice Day!
  13. Jan 17, 2012 #12
    You might ask some of the guys over there. Many did build their cars in garages at home. Not all but many. Many would have good ideas how to make an easier to weld frame.
  14. Jan 17, 2012 #13
    Popular Mechanics doesn't have a forum.
    it may look like forum but i believe the answers
    are provided by them.
    enough about that.
    i think the forum members here are much brighter
    than magazine writers.:smile:

    Have A Nice Day!
  15. Jan 17, 2012 #14
    Popular Mechanics?

    Oh, sorry I see, no I was talking about asking the Apexspeed guys, not PM. I can see how that wasn't clear in the post but that is what I meant.
  16. Jan 17, 2012 #15
    Send money first, then princes.:approve:
  17. Jan 18, 2012 #16

    Ranger Mike

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    Gold Member

    i have been on APEXspeed for 10 years...good info source
    as long as you know pitfalls of pushrod suspensions ..go for it..it is a bear on wear though..
  18. Jan 18, 2012 #17
    ranger mike
    i guess you could call it 'pushrod' suspension.
    it's a little distracting with 'pushrods' for engines.
    yeah i know no pushrods in those engines.
    it's really a bellcrank mechanism.
    it's also grossly overloading the small bellcrank
    from a classic engineering viewpoint.
    the metallurgy let's them get by with it.
    anyhow that's for somebody else, not me.
    i'm just playing Jim Hall here.:smile:

    Have A Nice Day!
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