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Thread: Rear 4 bar question

  1. #1

    Rear 4 bar question

    Hi all.
    Got a question about 4 bar.
    Building a car using all the bits of have lying around and have a bit of an issue with a shortage of space in the rear suspension area.
    So....what are your thoughts on mounting the lower arms in the conventional manner,and the mount the upper ones pointing rearward?A bit of thought with the angles of the bars matching should negate any pinion angle change i think.

    But,my main concern comes from many years ago when a friend had his 55 Chevy pro streeted by who was then(and still is probably)one of the most highly regarded engineers/builders in the UK scene,and he mounted the rear axle in this way.(with a fancy watts linkage).

    Car seemed to drive great and no problems were ever encountered with it but i do recall at one show someone told me that that style of set up was a no no,and from memory his reason was that under braking the rear wheels are unloaded.
    I could have got it completely wrong,it was probably more than 25 years ago and my memory is not that good.

    So basically,in your opinion will it/does it work?

    Thank you.
    That cars fine lookin`man
    Its somethin`else!

  2. #2
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    I dunno the answer but I can tell you that the original builders incarnation of the T bucket that has become notorious under the ownership of Andy Fadster had the top bars facing rearwards! I have no idea how much of the original care remains (it can't be much!?) and in what configuration although my best guess would be that the rear is now more conventionally mounted, but maybe not?

    Chris
    Bumper sticker - This is an historic vehicle and only has three speeds....... if you don't like this one you sure as hell won't like the others.

  3. #3
    LOL!
    That cars fine lookin`man
    Its somethin`else!

  4. #4
    NSRA member kapri's Avatar
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    Two different arcs of travel and fixed other side of axle ( viewed from side ) will bind . You can do it with 4 bars forward with antiroll bar backwards but then you have to add a link to allow movement or again it will lock out. I had to change set up on Ray Austins Y Roadster to floating rear anti rollbar as the original design locked them out. If you are struggling for space how are you going to fit in the coil overs ?
    Galations 6:7

  5. #5
    Moderator Brizey's Avatar
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    How much room is there behind the axle Mark?, Marcos cars had the 4 bar mounted behind the axle with the bars going towards the rear of the car and it worked fine!. Having the bars behind causes the axle to `arc` backwards instead of forwards as they normally would but it`s not detrimental to axle or prop-shaft movement!...

    Reverse Rear_Suspension.jpg
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  6. #6
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    Purely by coincidence i just saw this!

    Bumper sticker - This is an historic vehicle and only has three speeds....... if you don't like this one you sure as hell won't like the others.

  7. #7
    Great chaps. Thank you.
    That cars fine lookin`man
    Its somethin`else!

  8. #8
    Quote Originally Posted by Happydaze View Post
    Purely by coincidence i just saw this!

    ����Thats the sort of thing!
    That cars fine lookin`man
    Its somethin`else!

  9. #9
    Quote Originally Posted by kapri View Post
    Two different arcs of travel and fixed other side of axle ( viewed from side ) will bind . You can do it with 4 bars forward with antiroll bar backwards but then you have to add a link to allow movement or again it will lock out. I had to change set up on Ray Austins Y Roadster to floating rear anti rollbar as the original design locked them out. If you are struggling for space how are you going to fit in the coil overs ?
    Think i get that Kev thanks. Plenty of room for the coilovers. Can go triangulated but upper bars would be quite short.
    That cars fine lookin`man
    Its somethin`else!

  10. #10
    NSRA member Morris460's Avatar
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    Have a look at three link set ups.
    "That which can be asserted without evidence can be dismissed without evidence." Christopher Hitchens.

  11. #11
    NSRA member kapri's Avatar
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    Quote Originally Posted by Happydaze View Post
    Purely by coincidence i just saw this!


    I'm all ears , tell me how that works ? Unless there's something very trick that I'm missing all that's stopping that crashing to the ground is the rear link ?
    Galations 6:7

  12. #12
    NSRA member kapri's Avatar
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    Quote Originally Posted by Mark Bull View Post
    Think i get that Kev thanks. Plenty of room for the coilovers. Can go triangulated but upper bars would be quite short.
    Shame I missed you when you picked those wheels up or we could have spent some time going through it.
    Galations 6:7

  13. #13
    NSRA member rem's Avatar
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    Quote Originally Posted by kapri View Post
    I'm all ears , tell me how that works ? Unless there's something very trick that I'm missing all that's stopping that crashing to the ground is the rear link ?
    I'm thinking that triangulated forward link is pushing on a coilover at the top? Or maybe just a spring, as there is a pair of shocks already there?
    Sent from my Kitchen Table using a little box full of smoke and dangerous radio waves


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  14. #14
    NSRA member Morris460's Avatar
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    Yup, spring off the forward link and de-coupled mountings plus a torque arm (the only way this will work).
    "That which can be asserted without evidence can be dismissed without evidence." Christopher Hitchens.

  15. #15
    NSRA member Morris460's Avatar
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    "That which can be asserted without evidence can be dismissed without evidence." Christopher Hitchens.

  16. #16
    Looking at that last pic there appears to be a now redundant upper coilover mount on the chassis placing the coilover just in front of the axle.
    Neil.

  17. #17
    Quote Originally Posted by kapri View Post
    Shame I missed you when you picked those wheels up or we could have spent some time going through it.
    Only round the corner.Can pop in anytime.
    That cars fine lookin`man
    Its somethin`else!

  18. #18
    Quote Originally Posted by Morris460 View Post
    Have a look at three link set ups.
    Will have a google.You got any pics?
    That cars fine lookin`man
    Its somethin`else!

  19. #19
    Have had another think over there today.Anyone see any issues with mounting the upper bar slightly inboard of the lower one?
    I can mount the lower one directly under the chassis rail and the upper one can go alongside and bolt through.
    Its a fully fendered Model A so the chassis rails are relatively high of the ground.
    That cars fine lookin`man
    Its somethin`else!

  20. #20
    Quote Originally Posted by Morris460 View Post
    Have a look at three link set ups.

    Have been and had a look.Thanks.
    Sort of answers my question about mounting upper links inboard of lower ones too.
    That cars fine lookin`man
    Its somethin`else!

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