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Ball joints or struts and shocks?

Discussion in 'Z3 Roadster & Coupé' started by Don N, Mar 9, 2014.

  1. Don N

    Don N Dedicated Member

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    Location:
    Maryland USA
    Model of Z:
    3 - 2.8
    My next long-term project will be rebuilding the suspension in my 80,000 mile Z3 2.8. This is a weekend car, and will not go on the track (nor could it, as a soft-top car). I want it to stay stock, but upgraded. Based on the wheels, I think it may have the sport package option.

    One (reliable) mechanic says it's going to need new ball joints in the next year. So, that's a package of new control arms, centered polyurethane control arm bushings, sway bar links and tie rods. Roughly $400 in parts, plus labour.

    The trouble is, I really don't notice loose steering, steering wheel shake or tramlining. The car drives rock-solid at high speeds. Further, what I read tells me that replacing the control arms and bushings is an 80-100,000 mile maintenance item.

    What I DO notice is the wheels fluttering over small bumps in the road, and soft responses over larger lumps and humps. I also notice some vague responses from the rear of the car, such as a very quick transition from understeer to oversteer.

    It seems to me that I should start by replacing the rear shocks, then the struts, all with new mounting hardware, before investing in the control arms and bushings. While it would be great to do it all at once, finances require a staged process.

    Your thoughts?
     
  2. zedonist

    zedonist Guest

    Fully agree
     
  3. ge45ton

    ge45ton Zorg Legend
    East Anglian Crew The M44 Massive

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    agree with that too, then the rear wishbone bushes, maybe with M bushes rather than poly?
     
  4. zedonist

    zedonist Guest

    Standard bushes for me, but upgrade shocks and ARB's
     
  5. vintage42

    vintage42 Dedicated Member
    American Zeds

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    I think that is caused by the original soft rubber (and now worn) differential carrier (also called rear subframe) bushings. The movement they allow is also transmitted to the differential mount on the trunk floor, which can tear the mounts tabs , and pop the welds in the subframe channel under the trunk floor. It is commonly thought that replacing the rubber bushings with more solid urethane stops the movement of rear end and takes stress off the trunk floor welds.
    http://www.iemotorsport.com/bmw/Z3-suspension-steering/Z3eurearsbfrmmount.html
    http://forums.bimmerforums.com/forum/showthread.php?280802-Clint-s-IE-install-tips
     
  6. zedonist

    zedonist Guest

    Adding stiffer materials, either concentrates or moves the stress, just stick with OEM bushes, parts wear over time, just replace them, nobody ever complained when these cars were new.
     
  7. vintage42

    vintage42 Dedicated Member
    American Zeds

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    Now that the cars are old, the soft rubber RSF bushings are being blamed not only for poor handling, but for failure of the trunk floor subframe:
    http://forums.bimmerforums.com/foru...nt-Diff-Mount-Failure&p=27385251#post27385251
    It is an extremely important subject worth reading:
    http://forums.bimmerforums.com/foru...-Subframe-Bushings-Prevent-Diff-Mount-Failure
     
    #7 vintage42, Mar 10, 2014
    Last edited: Mar 10, 2014