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  1. #1
    Join Date
    Apr 2005
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    Worcestershire
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    Suspension Geometry

    last weekend I bought an unfinished chassis for my next project, a Haynes Roadster.

    I've set myself the unenviable task of creating a 4x4 version with a 2.8 V6 (Sierra XR4x4 donor).

    Now there's going to be a lot of work to mount the front diff, shocks, steering rack, column and front prop shaft. At first glance they all want to be in the same place.

    The front near side drive shaft actually goes through the sump on a Sierra with the front diff hanging off the drivers side of the engine, but on a Haynes Roadster the front wheel axis is front of the engine as it is with most of our Cobras.

    So the question, are there any experts/book/websites out there talking about suspension/steering/drive shaft geometry?

    I think I know that all the pivot points (wishbones/drive shafts/steering rack) all need to be on the same axis so it's all going to need home made brackets bearing and alot of fabrication. But why are the wishbones different lengths, surely it makes sense to have all the pivots a vertical axis?

    Does this make sense to anyone or are these the ramblings of a mad man?
    Regards

    Craig Perry

    No, I'm not "repairing" it, I'm fine tuning its performance.

  2. #2
    Join Date
    Aug 2011
    Location
    Birmingham
    Posts
    304
    Upper arms usually shorter than lower arms to give you increasing neg camber as you go into bump - for 'handling'

    Plenty of books on the subject. Not my field but this one is rated by the guys at work - https://www.amazon.co.uk/Competition.../dp/185960644X

  3. #3
    Join Date
    Apr 2011
    Location
    Bishop Auckland
    Posts
    289
    hi Craig,
    Front suspension is probably the most difficult thing to do on any car. You have camber, caster, akerman angle, bump steer etc. Don't go into this half hearted - it's a lot of work and calculations. There's an Australian guy written a program to help with this - I think it's called 'susprog3d'. If I were you I would stick to the pick up points of whichever front suspension manufacturer you are going to use i.e. use the pickup points from the XR4x4 rather than try and make your own up.
    Good luck
    James
    James G
    Purple Dax / Ford 260/4 speed toploader all in need of TLC and cash but the dreams are there. Dream on - car now blue and finished, 4 years later....

  4. #4
    Join Date
    Feb 2011
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    Devon
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    246
    James you have a PM.

  5. #5
    Join Date
    Jan 2013
    Location
    Stavanger Norway (previously east Leeds)
    Age
    49
    Posts
    95
    Hi,
    I guess there is a lot of info available, but I find "Race and rally car source book"by Allan staniforth very usefull. https://www.amazon.com/Race-Rally-Ca.../dp/1859608469
    BRA 427. JE 3.9. Hard top. Old School.

  6. #6
    Join Date
    Feb 2011
    Location
    Devon
    Posts
    246
    James G (Fireball XL5) you have a PM.

    Regards
    Geoff

  7. #7
    Join Date
    Nov 2003
    Location
    West Midlands UK.
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    2,949
    Could you not use the complete front subframe from the donor with all the suspension, steering rack, hubs, brakes etc already mounted and set up a la the Sierra they came from. If the Sierra track is unsuitable some cutting and shutting on the subframe should sort it,. Then weld a mounting to the subrame on which to mount the front diff liberated from the drivers side of the engine. You will have a sump with a tube through it which used to be occuopied by the N/s driveshaft but it could either be left alone or plated.

    Extend the front propshaft to the new front diff and jobs a good'un.

    Cheers,

    Tony
    Supply by blagging, engineering by bodge......

  8. #8
    Join Date
    Aug 2011
    Location
    Birmingham
    Posts
    304
    Quote Originally Posted by TonyD View Post
    Could you not use the complete front subframe from the donor with all the suspension, steering rack, hubs, brakes etc already mounted and set up a la the Sierra they came from. If the Sierra track is unsuitable some cutting and shutting on the subframe should sort it,. Then weld a mounting to the subrame on which to mount the front diff liberated from the drivers side of the engine. You will have a sump with a tube through it which used to be occuopied by the N/s driveshaft but it could either be left alone or plated.

    Extend the front propshaft to the new front diff and jobs a good'un.

    Cheers,

    Tony
    Some of that might work but surely a Sierra front suspension is on struts which kind of snookers a complete front clip transplant.

  9. #9
    Join Date
    Apr 2005
    Location
    Worcestershire
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    Quote Originally Posted by russell_ram2 View Post
    Some of that might work but surely a Sierra front suspension is on struts which kind of snookers a complete front clip transplant.
    On the limited number of these I’ve seen photos of they use push rod suspension with the shocks either side of the centre line or running the length of the car either side of the engine.

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