Scrub radius, and offset importance

Discussion in 'Chassis' started by Brian.G, Jan 6, 2011.

  1. Truckinduc Forum Member

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    True. Im going to add another half inch adjustment to it. Also my very low ride height and in turn the shorter strut length will help also.

    If I can tell any negitave effects of the wheels I may try to machine down the wheel mating face to get some more offset.
     
  2. Admin Guest

    If you are after a wider track it's much better to use wider wishbones to create this because they move the KPI with the lower ball joint, a man of your talents and resources could easily make a pair up and then have sensible scrub, maybe even negative scrub and average ET wheels. It would save you having to further modify your top mounts that look great btw.
     
  3. Truckinduc Forum Member

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    Well I plan on making a tubular subframe and chromoly a arms. Ill be raising the motor up slightly so ill have to widen the track width slightly to keep the stock cv joints in their optimum range.

    what other benifits - drawbacks would moving the upper strut mounts inboard have?
     
  4. Truckinduc Forum Member

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    I guess I could also make some offset ball joint spacers that move the balljoints outward while keeping the knuckle in the same position. Not sure how much I could gain before I start running into rotor clearance issues. I plan on using spherical bearigs instead of ball joints also.

    maybe thats what you meant in your last post and im just now understanding it.
     
  5. Dave

    Dave Pedantic Old Fart Paid Member

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    Here you are Mike. All dimensions relative to the Ball Joint!

    NB. The change in the dimension of the Upright holes relative to the wheel bearing. This was where my initial measuring error was!

    [​IMG]
    [​IMG]
    [​IMG]
     
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  6. sparrow Forum Junkie

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    That's just amazing. :thumbup::clap:
     
  7. LeftcoastTigger Forum Member

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  8. Admin Guest

    Fantastic detail Daved. :thumbup: Trully an epic acheivment that is very time consuming - well done.

    I may update my drawings with all this detail and then take some readings in a sweep of my setup to see how the scrub changes as the supenion compresses.
     
  9. Dave

    Dave Pedantic Old Fart Paid Member

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    Thanks Tom, LCT n' sparrow.

    Quite right Tom it is time consuming, especially when dimensional errors and machine failures require re-draws, but I want to do it both for myself and CGTI members like yourselves. I only wish than I could be 100% sure that the numbers are perfect. I am 99% sure, but if anyone wants to point out errors, then please do. I believe most on here realise by now what a pedant I am so must also realise that I will not be upset at all to get things spot on.

    Many times in the past I have been accused of being a perfectionist!:o

    Not true! I just try to get everything exactly right.:lol:


    (except speeling of course)
     
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  10. Dave

    Dave Pedantic Old Fart Paid Member

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    30mm wide track - #1

    Alex (sparrow)

    As requested I have sketched out the set-up with wishbones extended 30mm.

    If you can supply me with details of your wheels and tyres, IE:

    Dia, Rim Width and ET, plus a dynamic rolling radius, I'll draw the details in.

    If you can put your car on a really flat surface, and measure the height under the subframe at 'X', I'll be able to draw your exact set-up!

    [​IMG]
     
  11. jonlikescad Forum Member

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    Daved, any chance you could send me that design info on the mk2 front suspension? I really need some for a mk2/corrado project I'm working on and haven't been able to find it anywhere!

    Is it in some form of CAD?

    Cheers,

    Jon. :thumbup:
     
  12. sparrow Forum Junkie

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    Brilliant, thanks Dave. :thumbup:
    Wheel details are OZ Superleggera, 15" diameter, 7" wide, et 35.
    The car is in pieces now, so I don't have the dynamic rolling radius (or x), but I'll be using Toyo R888s which have a nominal diameter of 22.6".

    When the car's back together I'll measure x. Don't hold your breath. Unless you like the colour blue.
     
  13. Dave

    Dave Pedantic Old Fart Paid Member

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    Alex.

    What is the section and aspect ratio of the Toyos?

    There is a really good web page, if I can find it again, which works out dynamic radii for wheels using full data.

    Dave.
     
  14. Dave

    Dave Pedantic Old Fart Paid Member

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    Jon.

    Read the posts below. Can't remember which?

    You are not the first to ask, and if I can I will.

    Dave.
     
  15. strimmer Forum Member

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    Epic drawings, thank you!

    Started revising my spreadsheet and hope it will allow changes to wishbone lengths, adjustable top mounts, ride height and camber too.

    Trying out changes in suspension travel, shows that for a 40mm change in travel up and down scrub can go +- 2mm.

    Sound on track (excuse the lame pun) :thumbup:
     
  16. sparrow Forum Junkie

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    195/50/15s is what I ran before.
     
  17. sparrow Forum Junkie

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    This one?
     
  18. Dave

    Dave Pedantic Old Fart Paid Member

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  19. sparrow Forum Junkie

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  20. Dave

    Dave Pedantic Old Fart Paid Member

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